每月彙整: 2018 年 9 月

樹莓派、樹莓派之學習、樹莓派之教育

樹莓派 3B+ 筦窺︰ GigaBit

莊子、外篇『胠篋第十』上有一段文字︰

故跖之徒問於跖曰：「盜亦有道乎？」跖曰：「何適而無有道邪？ 妄意室中之藏，聖也；入先，勇也；出後，義也；知可否，知也；分均，仁也。五者不備而能成大盜者，天下未之有也。」由是觀之 ，善人不得聖人之道不立，跖不得聖人之道不行；天下之善人少而不善人多，則聖人之利天下也少而害天下也多。

並有雜篇、盜跖第二十九一段故事，讀來令人津津有味，難道義賊廖添丁乃盜跖之傳人乎？東方的『大盜』哲學和西方的『駭客』觀點能否作比較呢？如果要比較，當然得知道 hacker 的源流 。有位 Ben Yagoda 先生寫了一篇『 Hack 簡史』寫的很好。在此簡略的介紹，文中首先引用作者與美國方言學會會長談 “hack” 和 “hacker” 時的對話，會長說︰

the earliest examples share a relatively benign sense of “working on” a tech problem in a different, presumably more creative way than what’s outlined in an instruction manual.

也就是說最早所謂駭客是「創造性的使用說明書，用不一樣的辦法解決工程問題的人」。其後作者寫到，“hack” 一字 1955年就在 M.I.T 出現了，到了 1975 年 M.I.T 的電腦行話語詞表開啟了將 hacker 用於對電腦狂熱份子的宣言，並於所謂『八條定義』中開宗明義的說「駭客原指用大刀闊斧作傢俱的人」；其中第八條寫到︰

[deprecated] A malicious meddler who tries to discover sensitive information by poking around. Hence password hacker, network hacker. The correct term for this sense is cracker.

此條中〔勿用〕deprecated 一詞所說的『懷著惡意愛管閑事』者成了今天的黑帽駭客，或乾脆說黑客；相反的『本著活潑創造精神』者則變成今天的白帽駭客，也許簡稱為素客。同時作者論及駭客一詞的詞意變化、應用領域擴大…等等，於此就不多贅敘了。

十年後，1985 年法國心理學家愛德華·德·波諾著作『六頂思考帽』 ，在此引用中文維基百科上的兩頂帽：

黑色思考帽：代表缺點，隱患，問題，風險；當戴上黑色思考帽， 代表專注於考慮事情的負面，思考短,中,長期的風險，潛在與明顯的危機，是一頂行動前必須帶上的帽子。

白色思考帽：提供事實與數據，還包含考慮事情的各個面向，必須深入地挖掘事實，也必須將他人的意見考慮進來。

想想也許光明與黑暗，正是人同此心、心同此理的。希望能用正面思維來看待駭客一詞，就如同這本書名所想說的︰

Raspberry Pi Hacks
Tips & Tools for Making Things with the Inexpensive Linux Computer
By Ruth Suehle, Tom Callaway

那難道『大盜』與『駭客』真的能比較嗎？前面談了駭客的觀點，現在說說大盜的哲學。老子的哲學反對人為的矯飾，強調人為的禮儀並非自然而然。所以他講『大白若辱 』、『大音希聲』、『大象无形』、…等等，是非常重要的『逆向思維』觀念，能打破僵固的教條主義，莊子發揚老子的哲學，以其獨特的『創造性寓言』撼動著讀者的心靈，所以寫『逍遙遊』、『齊物論』、…以及論說「至大无外、至小无內」種種。因此從『創造性』方面來看，東西方或可相通，由『義』的角度來講，東西方亦或不相同。

─── 《盜亦有道？》

 

如果一個人能用

六頂思考帽

這方法強調從不同角度思考同一個問題，客觀地分析各種意見，最後作出結論。六帽子：紅、黃、黑、綠、白和藍。

  • 白色思考帽：提供事實與數據，還包含考慮事情的各個面，必須深入地挖掘事實，也必須將他人的意見考慮進來
  • 紅色思考帽：代表情緒，直覺，感覺；當戴上紅色思考帽，代表允許表達自己的喜好與感覺，運用在投票與決策
  • 黃色思考帽：代表好處，利益，價值；當戴上黃色思考帽，代表專注於考慮事情的正面，思考短、中、長期的好處、價值與利益 ，也包含了挖掘潛藏的優點
  • 黑色思考帽：代表缺點，隱患，問題，風險；當戴上黑色思考帽 ，代表專注於考慮事情的負面，思考短,中,長期的風險，潛在與明顯的危機，是一頂行動前必須帶上的帽子
  • 綠色思考帽：代表創新與創意，是一頂創意帽，水平思考就是綠帽的延伸
  • 藍色思考帽：是一頂控制思維的帽子，也稱為帽子的帽子，是一頂主持帽,系統地使用帽子時，必須以藍帽為開始，藍帽為結束

 

來思考，將通『逆向思維』乎？

那麼假設『問題答案』︰

RPi 3B+ gigabit ethernet bad download speeds.

Tue Mar 20, 2018 12:20 pm

Please can someone confirm download ethernet speeds on new RPi 3B+ with program speedtest-cli?
sudo apt-get install speedtest-cli

I have tested the new RPi 3B+ over a fresh install latest raspbian and official PSU raspberry pi and good SD card A1 class.
The performance on download speeds from internet is about 40 Mbit/s but my ISP is 200 Mbit/s and on my old Rpi3B I obtain 80 Mbit/s download speed.

I believe is a problem with kernel driver.I hope is not a related hardware problem.

In this web page someone discover similar problem…

https://volumio.org/raspberry-pi-3-b-pl … o-review/

“So, it seems that there is still some issue (hopefully it’s driver related) to the Ethernet controller, which seems to give up lots of packets in high-bandwidth situations. I am however pretty confident that the foundation will solve this issue, as it’s not uncommon that hardware performances get dramatic improvements as software gets tuned up after community feedbacks.”

Thanks in advance.

…

 

為已知︰

Re: RPi 3B+ gigabit ethernet bad download speeds.

Wed Aug 29, 2018 10:50 am

Eichhorn18 wrote: ↑

Wed Aug 29, 2018 9:06 am

jamesh wrote: ↑

Tue Jun 05, 2018 10:05 am

There is a suspected issue with Samba (and perhaps other network sharing mechanisms) that we haven’t got to the bottom of yet, that may be unrelated.

The speedtest-cli result look exactly like flow control is not working effectively.

Is there any known issues with cifs as an alternative to samba?

Just for another data point, I have 800 Mbit/s service and i’ve connected a laptop with gigabit ethernet and gotten that delivery speed. The Raspberry Pi 3B+ on the same physical wire gives between 120 – 165 Mbit/s download, and upload between 100 – 220 Mbit/s.

CIFS is a dialect of the SMB protocol that Samba implements.
We’re fairly certain that has been resolved now anyway. It was stalling a single TCP connection rather than a speed issue.
https://github.com/raspberrypi/linux/issues/2449
https://github.com/raspberrypi/linux/issues/2482

Yours sounds like the standard type of flow control issue. You have a bottle-neck in the USB2 interface from the ethernet adapter to the Pi of a theoretical max of 480Mbit/s, but more realisitcally around 250Mbit/s. The adapter will be sending ethernet flow control pause frames when it backs up, but those only work over the local network. There is no mechanism to make an internet server back off other than rely on TCP’s standard backoff/retry mechanisms.

……

Re: RPi 3B+ gigabit ethernet bad download speeds.

Fri Aug 31, 2018 1:09 pm

Eichhorn18 wrote: ↑

Fri Aug 31, 2018 11:46 am

drgeoff wrote: ↑

Thu Aug 30, 2018 4:16 pm

Copied from where on the 3B+? How fast can that place source data continuously?

Copied from the SD card. I realize that in itself is an unfortunate bottleneck.

I have also written files that are stored in RAM, directly to a network mounted folder on a windows machine using CIFS. The transfer speed from RAM to the network folder (over a gigabit network and onto a gigabit enabled machine) was 30 MB/s, transferring 184MB of files in 6.13 sec.

Well, from RAM you get 30 Mbyte/s. That is 240 Mbit/s which is approaching the expected max rate of ethernet on a RPi 3B+.

Re: RPi 3B+ gigabit ethernet bad download speeds.

Fri Aug 31, 2018 3:05 pm

drgeoff wrote: ↑

Fri Aug 31, 2018 1:09 pm

Well, from RAM you get 30 Mbyte/s. That is 240 Mbit/s which is approaching the expected max rate of ethernet on a RPi 3B+.

It’s true that is pretty decent. I wonder why the big difference (approximately 50%) for an internet connection that is supposed to give 800 Mbits/s on gigabit ethernet computers. What is the raspberry Pi doing for a speed test that it’s not doing for a local network transfer–assuming the internet connection is not the limiting factor.

 

可否『還原過程』也！

 

 

 

 

 

 

 

樹莓派、樹莓派之學習、樹莓派之教育

樹莓派 3B+ 筦窺︰ 【POE】 To GigaBit

internet1

清代  歸莊《觀田家收獲》
稻香秫熟暮秋天，
阡陌縱橫萬畝連。
五載輸糧女真國，
天全我誌獨無田。

 

中醫觀象上說︰火燄紅嚐苦入於心處之小腸，土色黃味甜趨於脾居之胃，…；講的是四季頤養之道依時進補之法。或許網路道荼蓼一文，可與之相通；所謂荼蓼離目之火 ☲，蔗坤地之甘 ☷， 自然能得離日耀目出地中天的 ☲ ☷ 晉卦之進取之境，所以才倒吃甘蔗。

俗話說『民以食為天』，今日不吃『英特乃』大概不能活了！！頭上既有青天白雲，腳底常陪綠地嫩草，奈何伊只顧低頭？一指觸知天下事？一個奇想帶來的蝴蝶效應，豈只驚天動地，簡直併吞了地球，不過英特乃是否真源自『地球村』之『桃花源』尚待『考證』 。之前講了『其人其事』，現在就談談『其物』──  乙太網 ──吧。人們一般以為乙太網發明於 1973 年，其因在於 Robert Melancton “Bob” Metcalfe 工作於全錄 PARC 時，受到 ALOHA 網路架構的啟發 ，寫了一張給他老闆有關乙太網潛力的備忘錄。但是梅特卡夫自己卻認為乙太網是其後幾年才出現的，至少應該說是在 1976 年和他的助手David Boggs 發表了一篇名為《乙太網：區域網路的分封交換技術 》的文章之後。不論早三年還是晚三年，大體與 ARPA 網之父的時期相當；作者試著簡化長篇歷史，假借卦象比之擬之的對比，祈能易懂易讀。

澤風大過 ☱ ☴根莖葉網際網路
上六，過涉滅頂，
凶，旡咎。		一套網際網路規範
Internet Protocol Suite
九五，枯楊生華，
老婦得其士夫，旡咎旡譽。		應用層
Application Layer
九四，棟隆，
吉，有它吝。		傳送層
Transport Layer
九三，棟橈，
凶。		網際網路層
Internet Layer
九二，枯楊生稊，
老夫得其女妻，旡不利。		網路存取層
Network Access Layer
初六，藉用白茅，
旡咎。		實體層
Physical

白茅

稻子

易繫辭上孔子說︰初六，苟錯諸地而可矣。藉之用茅，何咎之有？慎之至也。夫茅之為 物薄而用可重也，慎斯術也以往，其无所失矣。『藉』字在甲骨文中就有，是古代供人祭拜时站跪的草墊。這個草墊不知有沒有什麼講究，或是一定要用什麼『特殊的』的草嗎？據南懷謹先生談此爻時說，古人過年會送朋友『年糕』── 高 ──，下面用『稻草』墊著；然而祭神要的是『誠心』，送禮講的是『誠意』，包裝之用藉能誠心誠意就是『慎重其事』，並不須要特別考究，用白茅當然沒有『咎害』，就是不用只放在地上也沒有什麼不可。能得無咎之人善於補過擇善而遷！！

……

上六：過涉滅頂，凶，無咎。
象曰：過涉之凶，不可咎也。

彖曰：大過，大者過也。 棟橈，本末弱也。 剛過而中，巽而說行， 利有攸往，乃亨。 大過之時義大矣哉！
象曰：澤滅木，大過﹔君子以獨立不懼，遯世無悶。

事有本末物有終始，即使如莊子說的大椿木，八千年為春，八千歲為秋，都不免有終了之時，如將之立於雲夢大澤，若是根本動搖，也難保沒滅頂之災！！英特乃擴大了人們言論的力量能無遠弗屆，須注意彼此共有的自由，多一些網路禮儀可能更好。雖然食衣住行育樂全可以在網際網路上得到，少一點網路沈迷或許不是壞事！！

─── 《咬一口 TCPIP！！上》

 

無論樹莓派基金會 PoE HAT 問題的最終解決方案是什麼？此處暫時放下，且說個『相關問題』︰

RPi 3B+ gigabit ethernet bad download speeds.

Tue Mar 20, 2018 12:20 pm

Please can someone confirm download ethernet speeds on new RPi 3B+ with program speedtest-cli?
sudo apt-get install speedtest-cli

I have tested the new RPi 3B+ over a fresh install latest raspbian and official PSU raspberry pi and good SD card A1 class.
The performance on download speeds from internet is about 40 Mbit/s but my ISP is 200 Mbit/s and on my old Rpi3B I obtain 80 Mbit/s download speed.

I believe is a problem with kernel driver.I hope is not a related hardware problem.

In this web page someone discover similar problem…

https://volumio.org/raspberry-pi-3-b-pl … o-review/

“So, it seems that there is still some issue (hopefully it’s driver related) to the Ethernet controller, which seems to give up lots of packets in high-bandwidth situations. I am however pretty confident that the foundation will solve this issue, as it’s not uncommon that hardware performances get dramatic improvements as software gets tuned up after community feedbacks.”

Thanks in advance.

 

然因其中文字攻防，涉及『網路禮儀』，故先引『論壇規則』︰

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希望大家能以

嚴以律己，寬以待人。

為態度，緊扣議題，文明論辯也◎

少點『以人廢言』抑或『以言廢人』之是非呦☆

通常過多的『情緒』及『企圖』︰

Re: PoE HAT – USB Ports not working – over-current

Wed Sep 12, 2018 7:44 pm

For anyone who needs a quick fix, here is our PoE HAT (tried and tested for 3+ years) which does not face the same issue and as a plus works with any 40 pin Pi (not just 3B+) – https://uk.pi-supply.com/products/pi-po … spberry-pi

Will be back in stock in around a week :-)

…

Re: PoE HAT – USB Ports not working – over-current

Wed Sep 12, 2018 9:10 pm

That bulky thing on top is the reason I didn’t buy yours ;-)
The Raspberry Pi HAT still fits inside a normal case, and doesn’t have the ugly passthrough cable.

…

Re: PoE HAT – USB Ports not working – over-current

Thu Sep 13, 2018 2:45 pm

shawaj wrote: ↑

Wed Sep 12, 2018 7:44 pm

For anyone who needs a quick fix, here is our PoE HAT (tried and tested for 3+ years) which does not face the same issue and as a plus works with any 40 pin Pi (not just 3B+) – https://uk.pi-supply.com/products/pi-po … spberry-pi

Will be back in stock in around a week :-)

Gigabit ethernet supported?
That’s the one that many of the plug in PoE widgets miss out on and only support 10 or 100 Mbit/s.

……

 

容易忘了『他山之石，可以攻錯』哩★

記得 3B 那時候，見過那塊板子︰

今日測試以饗讀者︰

※ 註︰ 事實不支援 GigaBit 網路。

pi@raspberrypi:~ cat /proc/version  Linux version 4.14.69-v7+ (dc4@dc4-XPS13-9333) (gcc version 4.9.3 (crosstool-NG crosstool-ng-1.22.0-88-g8460611)) #1141 SMP Mon Sep 10 15:26:29 BST 2018 pi@raspberrypi:~  pi@raspberrypi:~ speedtest-cli 
Retrieving speedtest.net configuration...
Testing from HiNet (36.231.24.245)...
Retrieving speedtest.net server list...
Selecting best server based on ping...
Hosted by Taiwan Fixed Network (Taipei) [1.62 km]: 18.393 ms
Testing download speed................................................................................
Download: 92.24 Mbit/s
Testing upload speed....................................................................................................
Upload: 38.74 Mbit/s

pi@raspberrypi:~ sudo ethtool -s eth0 speed 100 duplex full pi@raspberrypi:~ speedtest-cli 
Retrieving speedtest.net configuration...
Testing from HiNet (36.231.55.241)...
Retrieving speedtest.net server list...
Selecting best server based on ping...
Hosted by Taipeinet (Taipei) [1.62 km]: 19.445 ms
Testing download speed................................................................................
Download: 92.69 Mbit/s
Testing upload speed....................................................................................................
Upload: 38.91 Mbit/s
pi@raspberrypi:~ $

 

 

 

 

 

 

 

 

樹莓派、樹莓派之學習、樹莓派之教育

樹莓派 3B+ 筦窺︰ 【POE】 USB Boot ？★‧硬體‧省思

碩果不食

□︰今已有兩極四方，恐入八卦矣！

○︰所為何事？

□︰圍城而不攻？是何故耶？？

○︰是所謂碩果不食。能上不能下？窮之災！囧之禍乎？？

○︰《易》有剝極來復之道！！

與時並進者遭遇『困難』，面對『未知』是再自然不過的事。如之何『求解』正砥礪著學者的『百折不撓』之精神。『九天九地』的探尋，難到不會有『一陽來復』之時？深體自由軟體者之心？？

假使仔細閱讀《 Device Tree on ARCH_BCM2708 》，留心一下『那個人』── notro ── 與『那個時間』── on Jul 30, 2014 ──，也許我們不只對樹莓派『裝置樹』有更多的了解，更能明白許多的貢獻其來有自，正所謂『德不孤，必有鄰』乎！！

─── 《大樹底下好乘涼 ︰ 《拜樹頭》 ？ ※ 碩果不食》

 

當人們面對『已知』問題︰

Re: PoE HAT – USB Ports not working – over-current

jamesh

Tue Sep 11, 2018 2:22 pm

OK all, as some will have seen on the Register (www.theregister.co.uk) we think we have got to the bottom of this. Here is a letter from Eben sent to the Register, who had asked what was up after some of their readers got in touch.

We’ve been looking at this over the last week, and have a good handle on the underlying mechanism: it’s an interaction between the fairly low-frequency switching regulator on the HAT, and one of the two brands of USB current limiting switch that we use on the main board. Because the regulator operates at a fairly low frequency, each time it switches it moves quite a large chunk of energy into the three USB reservoir caps via the current limiting switch: this large instantaneous current is fooling the switch into thinking that a genuine over-current event is occurring. We missed it in product testing because (dumb luck) our heavy-load testing was done on boards with the other brand of switch, and most of our field testers were only using the board to power mice and keyboards, which works fine on all the HAT/Pi pairs we’ve tested.

There will be a blog post of gory details, probably tomorrow, but for now the summary is:

– A significant proportion of HAT/Pi pairs are limited to delivering <200mA of downstream current to USB. This is generally enough for mice and keyboards, but not for e.g. hard drives.
– We will fix this issue in a subsequent spin of the PoE HAT.
– In the meantime we’ll be adding a note where the HAT is sold, documenting this limitation.
– We will provide a couple of hand-mod options for adventurous users. These are likely to be:
– Removing reservoir caps from the main board (an easy, clean mod if you can use a soldering iron, but limits USB hotpluggability).
– Inserting a small amount of series impedance in the current path from the HAT (this one will be a bit fiddly to implement).
– Users who have bought a HAT and are inconvenienced by this issue should return it for a refund.

The moral of the story: do more testing, particularly where we have multiple vendors for key bits of silicon.

I hope that covers all the questions that have been asked above.

 

五花八門『想法』蹦然而出，宛如『腦力激盪』，豈不好乎？

Re: PoE HAT – USB Ports not working – over-current

Tue Sep 11, 2018 5:13 pm

drgeoff wrote: ↑

Tue Sep 11, 2018 3:33 pm

raspy1 wrote: ↑

Mon Sep 10, 2018 8:03 pm

An extra question: is anyone knows if there is a power priority management if both 5V PSU & PoE are connected?

I can’t see that is any different from powering via the micro-USB socket and the GPIO header at the same time.

There is no sensing upwind of the output side of the polyfuse which could be used to know that both micro-USB and GPIO header (PoE HAT if fitted) are powered. And even if there was there is no controllable switch on the micro-USB input to turn off supply of power from there.

No there is some prioritisation going on here, though how/what/where will need to be explained by others.

If I power up the Pi with PoE then connect a micro USB power supply, then disconnect the USB, the hat power cycles. Removing the network cable doesn’t cause the Pi to power cycle. The network switch shows that as soon as I connect the micro USB Power supply it stops delivering power over Ethernet.
If I power up the Pi with Micro USB power supply and then add the Ethernet Cable, power is only drawn from the Micro USB supply, at least as reported by my PoE Switch.

Martin

 

還得『省思』 Y -解法之『利』與『弊』也！

派生碼訊

丑 牛

錦瑟‧李商隱

錦瑟無端五十弦，一弦一柱思華年。
莊生曉夢迷蝴蝶，望帝春心託杜鵑。
滄海月明珠有淚，藍田日暖玉生煙。
此情可待成追憶，只是當時已惘然。

白金西︰所謂明智，是能將事後之明﹐用於臨事之前。當真為『回反』者也。

─── 《M♪O 之學習筆記本《丑》控制︰【白金西】時回流反》

……

閱讀『美國線規』詞條有何樂趣耶？

或可拿來尋幽探秘乎？？

比方藉著 Tables of AWG wire sizes 

Fusing current

索引，或能開拓視野，認識歷史裡人物事蹟也！

Preece

Onderdonk

爾後面對『紅色條規』 Code Red 時︰

勿將電壓源短路。

將會反思鍊結『高溫、熔斷、火災、爆炸 …』吧！！

故知，雖曾有此

並聯電路

電池

假設一個電池組是以幾個單電池以並聯方式連接成電源，則此電源兩端的電壓等於每一個單電池兩端的電壓。例如，假設一個電池組內部含有四個單電池並聯在一起，它們共同給出1安培電流，則每一個單電池給出0.25安培電流。很多年前，並聯在一起的電池組時常會被使用為無線電接收機內部真空管燈絲的電源，但這種用法現在已不常見。

之用法，需得借『開關』避免

無『負載』時的內耗哩☺

那麼仔細衡量 R_L『範圍』及『安全顧慮』后，到底會不會定出

USB_(Physical)#Power

Where devices (for example, high-speed disk drives) require more power than a high-power device can draw,[45] they function erratically, if at all, from bus power of a single port. USB provides for these devices as being self-powered. However, such devices may come with a Y-shaped cable that has two USB plugs (one for power and data, the other for only power), so as to draw power as two devices.[46] Such a cable is non-standard, with the USB compliance specification stating that “use of a ‘Y’ cable (a cable with two A-plugs) is prohibited on any USB peripheral”, meaning that “if a USB peripheral requires more power than allowed by the USB specification to which it is designed, then it must be self-powered.”[47]

Peripheral Power Consumption

Mandate: Required
Effective Date: Now

The maximum current that any USB peripheral is permitted to draw from a standard USB 2.0 downstream port is 500mA. This includes USB 3.0 peripherals and peripherals that charge batteries from USB. For this discussion, a standard USB 2.0 downstream port complies with the definition of a host or a hub as defined solely in the “Universal Serial Bus Specification,” Revision 2.0 document.

The maximum current that a USB 3.0 peripheral may draw from a standard USB 3.0 downstream port is 900mA. USB 2.0 peripherals and USB 2.0 peripherals that charge batteries from USB are still limited to 500mA when attached to a standard USB 3.0 downstream port. For this discussion, a USB 3.0 standard downstream port complies with the definition of a host or a hub as defined solely in the “Universal Serial Bus 3.0 Specification,” Revision 1.0 document.

Use of a ‘Y’ cable (a cable with two A-plugs) is prohibited on any USB peripheral. If a USB peripheral requires more power than allowed by the USB specification to which it is designed, then it must be self-powered.

All upstream ports are required provide enumeration of USB functions.

必須如是的呢☆★

─ 摘自《STEM 隨筆︰古典力學︰轉子【五】《電路學》三【電阻】V.D》

 

因此特別找出『PowerPi 工程用電源組』

 

純假借為 5V/2A 之 『USB 電壓源』，證此『念頭』哩！？

那麼在實測 OK 後，安全『無虞』耶？！

何不務歸其本也☆

Re: PoE HAT – USB Ports not working – over-current

Thu Sep 13, 2018 7:27 pm

At least those experimenting here didn’t blow up their HATs like Dave EEVblog accidentally did: https://www.youtube.com/watch?v=Tpvjo6wDFUA
I wonder if the foundation will honour his warranty ;-)@jamesh I’ve dropped you an email. Feel free to get in touch. Sadly I’m not in Cambridge as often as I used to be, else I would have offered to drop in.

 

 

 

 

 

 

 

 

 

 

樹莓派、樹莓派之學習、樹莓派之教育

樹莓派 3B+ 筦窺︰ 【POE】 USB Boot ？★‧硬體‧尾

當讀片段濃縮文本

Armature Controlled DC Motor

A motor is an actuator, converting electrical energy in to rotational mechanical energy. Motor requiring DC supply for operation is termed as DC motor. DC motors are widely used in control applications like robotics, tape drives, machines and many more. Separately excited DC motors are suitable for control applications because of separate field and armature circuit. Two ways to control DC separately excited motors are:

1. Armature Control.

2. Field Control.

Modelling of armature control DC motor is discussed in the article.

It represents basic structure of separately excited DC motor.

Basic operating mechanism of a DC motor[1]

DC motor consists of two parts i.e. rotor and stator. Stator consists of field winding while rotor (also called armature) consists of armature winding. When both armature and field are excited by DC supply, current flows through windings and magnetic flux proportional to the current is produced. When the flux of field interacts with the flux of armature, it results in motion of the rotor. Armature control is the most common control technique for DC motors. In order to implement this control, the flux is required to be kept constant. To this aim, either the stator voltage is constant or the stator coils are replaced by a permanent magnet. In the latter case, the motor is said to be a permanent magnet DC motor and is driven by means of the only armature coils.

As in armature control, field flux is constant; equations governing operation of motor become linear that is

\displaystyle T=K_{\phi }\Phi \mathrm {I}  (1)

where T is motor torque, \Phi is flux and I is armature current. When field flux is constant, equation (1) becomes

\displaystyle T=K'\mathrm {I} (2)

where \displaystyle K'=K_{\phi }\Phi as \Phi is constant.

In addition, the motor has an intrinsic negative feedback structure, hence at the steady state, the speed \omega is proportional to the reference input V_a.

These two facts, in addition to the cheaper price of a permanent magnet motor with respect to a standard DC motor (as a matter of fact only the rotor coils need to be winded), are the main reasons why armature controlled motors are widely used. However, several disadvantages arise from this control technique, of which major is the flow of large currents during transients. For example, when started speed ω is zero initially hence back EMF (Electromotive Force) governed by the following relation, would be zero.

\displaystyle E_{b}=K_{\phi }\Phi \omega (3)

And also armature current is given by \displaystyle I=\left({\frac {V-E_{b}}{R_{a}}}\right) (4)

will be very high causing increase in heating of machine and it may damage the insulation.

Transfer Function

Essential Equations [1]:

Electrical Equations:

\displaystyle E_{b}(s)=K_{\phi }\Phi \omega (s) in Laplace domain \displaystyle E_{b}(s)=K_{\phi }\Phi \omega (s) (5)

\displaystyle I=\left({\frac {V-E_{b}}{R_{a}}}\right) in Laplace domain \displaystyle I(s)=\left({\frac {V(s)-E_{b}(s)}{R_{a}}}\right) (6)

\displaystyle T=K_{\phi }\Phi \mathrm {I} in Laplace domain \displaystyle T(s)=K_{\phi }\Phi \mathrm {I} (s) (7)

\displaystyle T-T_{L}=J{d\omega \over dt}+F\omega in Laplace domain \displaystyle T(s)-T_{L}(s)=J{d\omega (s) \over dt}+F\omega (s) (8)

Block Diagram of Separately Excited DC Motor is given in Fig.2

It represents block diagram of separately excited DC motor with armature control.

Various parameters in figure are described as

The transfer matrix of the system may be written as

\displaystyle \omega (s)={\begin{bmatrix}W_{1}(s)&W_{2}(s)\end{bmatrix}}{\begin{bmatrix}V_{a}\\T_{L}(s)\end{bmatrix}} (9)

where \displaystyle W_{1}(s)={\frac {K_{a}K_{\phi }K_{m}\phi }{(1+\tau _{a}s)(1+\tau _{m}s)+K_{a}K_{m}(K_{\phi }\phi )^{2}}} (10)

\displaystyle W_{2}(s)={\frac {K_{m}(1+\tau _{a}s)}{(1+\tau _{a}s)(1+\tau _{m}s)+K_{a}K_{m}(K_{\phi }\phi )^{2}}} (11)

 

能不感覺望文生義耶？

此時或不如鉅細靡遺咀嚼大部頭文章也！

DC motors: dynamic model and control techniques

 

然由『學問』貴在『善用』來講，恐又略嫌不足呦！？

─── 《STEM 隨筆︰古典力學︰轉子【五】《電路學》 五【電感】 IV‧馬達‧二‧D》

 

試問當已經知道 DC 轉子之『電路模型』，可否用『啟動電流』與『轉動電流』的差異，解釋 PoE HAT 小風扇可能引發之『現象』嗎 ？

若將 PoE HAT 看成

V(t) = V_{average} + V_{ripple} + V_{harmonic}

『不理想』電壓源，打算怎麼『改善』呢？？

Re: PoE HAT – USB Ports not working – over-current

The_Raven

Tue Sep 04, 2018 11:31 am

martinrowan wrote: ↑

Tue Sep 04, 2018 9:43 am

Is it the physical distance that makes the difference, for example with long leads/wires attached if you move it close to the RPi does it start to fail. Or is it the length/resistance of the cables that are making a difference?

Good question. I am not 100% sure. I think it is the distance.
In the next step i try to add the capacitors.
As told before: Have a look at the datasheet of the MP8007 chip. Specially the capacitor and the part with the red “X”.

Attachments
Schematic.JPG
Schematic.JPG (156.7 KiB) Viewed 503 times

……

Re: PoE HAT – USB Ports not working – over-current

The_Raven

Wed Sep 05, 2018 11:36 am

So we fixed it by adding 2 capacitors and one coil.
Now i can pull 1A from the USB. 8-)
It has still some noise, but it looks much better than before.
Now testing how stable it is, if the fan works and so on.
Attachments
Noise.JPG
Noise.JPG (133.93 KiB) Viewed 1169 times
Fix.JPG
Fix.JPG (153.39 KiB) Viewed 1170 times

※ 註︰

───

DC-to-DC converter

A DC-to-DC converter is an electronic circuit or electromechanical device that converts a source of direct current (DC) from one voltage level to another. It is a type of electric power converter. Power levels range from very low (small batteries) to very high (high-voltage power transmission).

……

Terminology

Step-down
A converter where output voltage is lower than the input voltage (such as a buck converter).
Step-up
A converter that outputs a voltage higher than the input voltage (such as a boost converter).
Continuous current mode
Current and thus the magnetic field in the inductive energy storage never reach zero.
Discontinuous current mode
Current and thus the magnetic field in the inductive energy storage may reach or cross zero.
Noise
Unwanted electrical and electromagnetic signal noise, typically switching artifacts.
RF noise
Switching converters inherently emit radio waves at the switching frequency and its harmonics. Switching converters that produce triangular switching current, such as the Split-Pi, forward converter, or Ćuk converter in continuous current mode, produce less harmonic noise than other switching converters.[17] RF noise causes electromagnetic interference (EMI). Acceptable levels depend upon requirements, e.g. proximity to RF circuitry needs more suppression than simply meeting regulations.
Input noise
The input voltage may have non-negligible noise. Additionally, if the converter loads the input with sharp load edges, the converter can emit RF noise from the supplying power lines. This should be prevented with proper filtering in the input stage of the converter.
Output noise
The output of an ideal DC-to-DC converter is a flat, constant output voltage. However, real converters produce a DC output upon which is superimposed some level of electrical noise. Switching converters produce switching noise at the switching frequency and its harmonics. Additionally, all electronic circuits have some thermal noise. Some sensitive radio-frequency and analog circuits require a power supply with so little noise that it can only be provided by a linear regulator.[citation needed] Some analog circuits which require a power supply with relatively low noise can tolerate some of the less-noisy switching converters, e.g. using continuous triangular waveforms rather than square waves.[17][not in citation given]

───

Switched-mode power supply

A switched-mode power supply (switching-mode power supply, switch-mode power supply, switched power supply, SMPS, or switcher) is an electronic power supply that incorporates a switching regulator toconvert electrical power efficiently. Like other power supplies, an SMPS transfers power from a DC or AC source (often mains power) to DC loads, such as a personal computer, while converting voltage and currentcharacteristics. Unlike a linear power supply, the pass transistor of a switching-mode supply continually switches between low-dissipation, full-on and full-off states, and spends very little time in the high dissipation transitions, which minimizes wasted energy. Ideally, a switched-mode power supply dissipates no power. Voltage regulation is achieved by varying the ratio of on-to-off time. In contrast, a linear power supply regulates the output voltage by continually dissipating power in the pass transistor. This higher power conversion efficiency is an important advantage of a switched-mode power supply. Switched-mode power supplies may also be substantially smaller and lighter than a linear supply due to the smaller transformer size and weight.

Switching regulators are used as replacements for linear regulators when higher efficiency, smaller size or lighter weight are required. They are, however, more complicated; their switching currents can cause electrical noise problems if not carefully suppressed, and simple designs may have a poor power factor.

……

Advantages and disadvantages

The main advantage of the switching power supply is greater efficiency than linear regulators because the switching transistor dissipates little power when acting as a switch.

Other advantages include smaller size and lighter weight from the elimination of heavy line-frequency transformers, and comparable heat generation. Standby power loss is often much less than transformers.

Disadvantages include greater complexity, the generation of high-amplitude, high-frequency energy that the low-pass filter must block to avoid electromagnetic interference (EMI), a ripple voltage at the switching frequency and the harmonic frequencies thereof.

Very low cost SMPSs may couple electrical switching noise back onto the mains power line, causing interference with A/V equipment connected to the same phase. Non-power-factor-corrected SMPSs also cause harmonic distortion.

 

或知『知』

Computationally efficient models for simulation of non-ideal DC–DC converters operating in continuous and discontinuous conduction modes

 

『行』合一，實在不易啊◎

 

 

 

 

 

 

 

 

樹莓派、樹莓派之學習、樹莓派之教育

樹莓派 3B+ 筦窺︰ 【POE】 USB Boot ？★‧硬體

假使奶油土司掉到地上，十之八九是塗奶油的那一面◎

如果依據『最糟情境』考察樹莓派 3B+ 電源線路︰

唯有當

V^{min}_{in} - R^{max}_{fuse} * I^{max}_{load} \ge V_{under \_ votage}

時，才能不發生『低電壓警訊』！

從 MF-MSMF-250/X datasheet 可知 R^{max}_{fuse} = 0.1 \Omega 。

一個符合 USB 規格之電源，在額定電流內，它的輸入電壓落在 5V \pm 5 \% 範圍裡。

如此 V^{min}_{in} = 4.75 V ，那麼不管假設 V_{under \_ votage} 是 4.65 V 或 4.63V ，最多只能容許 1.0 A 或 1.2A 電流哩！

更別說這時電壓恐已超出 USB 輸入範圍也？！

故知樹莓派基金會官網數字︰

POWER SUPPLY

The Raspberry Pi 3 is powered by a +5.1V micro USB supply. Exactly how much current (mA) the Raspberry Pi requires is dependent on what you connect to it. We have found that purchasing a 2.5A power supply from a reputable retailer will provide you with ample power to run your Raspberry Pi. You can purchase the official Raspberry Pi Power Supply from our website, and you can learn more about the differing power requirements of the various models of the Raspberry Pi on our FAQ page.

之合理性呦！？

既然為了安全，保險絲省不了；又為了 USB 裝置正常工作，V_{under \_ votage} 電壓設定低不了☻

不得不作此 V_{in} 升壓一途吧☺

─── 《STEM 隨筆︰古典力學︰轉子【五】《電路學》三【電阻】V.C》

 

承上篇，這麼多『Under-voltage detected!』訊息，

 

難到不是意味這時 PoE HAT『電壓不足』嗎？沒有『over-current change』警告，豈非暗示符合『USB 電源規範』哩！

一時心中忖度︰論壇裡，幾種『不同長度』之陳述︰

Re: PoE HAT – USB Ports not working – over-current

aduvenhage

Tue Sep 04, 2018 9:07 am

Yip, I also confirmed that removing the hat and connecting it with wires, made it work much better.
I connected 5V, 3V, GND, SDA0, SCL0 and the POE pins with wires and it works perfectly now.I tested again with shielding between the transformer and the little chip beneath it (with hat on header again), but still not working.Is there maybe an error on the POE Hat board? Like another header pin connected where it should not be?

………

Re: PoE HAT – USB Ports not working – over-current

The_Raven

Tue Sep 04, 2018 9:31 am

The picture is from my “first attempt”. So maybe it was wrong to post it because it “confuses”. We also tested it with all 40 pins connected trough a IDE-Cable and it works!
Then we tested it with a short IDE cable (3cm) and it has NOT worked. Then we cut pin for pin beginning from the gpio side. And with every cuted pin it has worked better.
We tested it also with only the power-pins connected (short version) and it works sometimes but is very buggy.
With long wires -> No problem (and i think this was not only luck, think i can confirm it).
I stay by my statement: It looks like a hardware problem.Hint: Take a look in the schematics from MP8007 datasheet.

………

Re: PoE HAT – USB Ports not working – over-current

martinrowan

Tue Sep 04, 2018 9:43 am

Thanks for all your work @The_Raven. Is it the physical distance that makes the difference, for example with long leads/wires attached if you move it close to the RPi does it start to fail. Or is it the length/resistance of the cables that are making a difference? I’m assuming it’s physical proximity.

Really hope the Engineering team are catching up on this thread and will come back with a response soon. Seems like a pretty fundamental issue we’re all facing.

………

 

望著可能的 PoE HAT 5V 輸出電壓『量測波形』︰

Re: PoE HAT – USB Ports not working – over-current

Blaster

Tue Sep 04, 2018 12:44 pm

My guess is that problem lies in converter output voltage filtering, excessive noise disturbing overcurrent supervising feature of USB controller producing false “over-current” messages.
In this type of applications the current monitoring is commonly realised as voltage drop sensing, so it’s usually sensitive to noise in applied voltage.
And measurements shows that 5V line at USB ports (while powered by PoE HAT) is very noisy, ringing spikes clearly produced by DC/DC converter switching at some 19kHz. Also the voltage ripple is quite high (at least to my sense).
Attachments
TEK00006.PNG
5V at USB port, no devices connected, powered by PoE HAT
TEK00006.PNG (9.44 KiB) Viewed 471 times

………

Re: PoE HAT – USB Ports not working – over-current

daytona

Wed Sep 05, 2018 10:26 pm

I’ve setup the PoE Hat on a small test rig tonight feeding a dummy load. The two load resistors across the 5 volt supply sink about 1.5amps.

testrig.jpg
testrig.jpg (82.13 KiB) Viewed 923 times

With the output capacitors fitted to the PoE HAT PCB the 5 volt output on my ‘scope looks like this. (2V/div, GND at centre)

scopenoise.jpg
scopenoise.jpg (48.96 KiB) Viewed 923 times

When I add an additional 470uF across the 5 volt output I see this (2V/div, GND at centre) There’s a bit of drop in the leads to the breadboard, but measuring the output on the HAT it’s 5.1 volts

scopeclean.jpg
scopeclean.jpg (48.54 KiB) Viewed 923 times

Looking at the MP8007 datasheet, it shows two reference designs, one with a 12 volt, 1 amp output. The other for a 5 volt 2.5 amp output.

I desoldered two of the ceramic output filter capacitors from the HAT and found the small one measures 22uF and the larger one at 63uF (4 x 63uF = 252uF). If you compare these values to the reference design the output filter capacitors fitted to the HAT give the values shown for the 12 volt / 1amp output reference design. And increasing the capacitance on the 5 volt output to something around that shown for the 5 volt output reference design appears to stabilises it.

 

突然想起所謂『風扇轉速』控制事件︰

PoE HAT Fan Speed adjustment

dr.sputnik

Thu Aug 30, 2018 4:01 pm

Hi,

I saw the notes in ETA for Official POE Hat for 3B+, and decided to try this on one of mine.

After editing, compiling and copying over the file to the overlays folder, the fan no longer works. Also the faint high pitch noise made by the PoE HAT during boot is absent. Copying the original overlay file back and rebooting results in it all working again.

I downloaded the code from https://github.com/raspberrypi/linux/ra … verlay.dts and edited it as follows:

pi@dtc1:~/fan-control cat rpi-poe-overlay.dts /*  * Overlay for the Raspberry Pi POE HAT.  */ /dts-v1/; /plugin/;  / {         compatible = "brcm,bcm2708";          fragment@0 {                 target-path = "/";                 __overlay__ {                         fan0: rpi-poe-fan@0 {                                 compatible = "raspberrypi,rpi-poe-fan";                                 firmware = <&firmware>;                                 cooling-min-state = <0>;                                 cooling-max-state = <3>;                                 #cooling-cells = <2>;                                 cooling-levels = <0 50 150 255>;                                 status = "okay";                         };                 };         };          fragment@1 {                 target = <&cpu_thermal>;                 __overlay__ {                         trips {                                 threshold: trip-point@0 {                                         temperature = <50000>;                                         hysteresis = <5000>;                                         type = "active";                                 };                                 target: trip-point@1 {                                         temperature = <55000>;                                         hysteresis = <2000>;                                         type = "active";                                 };                                 cpu_hot: cpu_hot@0 {                                         temperature = <60000>;                                         hysteresis = <2000>;                                         type = "active";                                 };                         };                         cooling-maps {                                 map0 {                                         trip = <&threshold>;                                         cooling-device = <&fan0 0 1>;                                 };                                 map1 {                                         trip = <&target>;                                         cooling-device = <&fan0 1 2>;                                 };                                 map2 {                                         trip = <&cpu_hot>;                                         cooling-device = <&fan0 2 3>;                                 };                         };                 };         }; }; pi@dtc1:~/fan-control

and then ran:

dtc -@ -I dts -O dtb -o rpi-poe.dtbo rpi-poe-overlay.dts

That command produces warnings:

pi@dtc1:~/fan-control dtc -@ -I dts -O dtb -o rpi-poe.dtbo rpi-poe-overlay.dts rpi-poe.dtbo: Warning (unit_address_vs_reg): Node /fragment@0 has a unit name, but no reg property rpi-poe.dtbo: Warning (unit_address_vs_reg): Node /fragment@0/__overlay__/rpi-poe-fan@0 has a unit name, but no reg property rpi-poe.dtbo: Warning (unit_address_vs_reg): Node /fragment@1 has a unit name, but no reg property rpi-poe.dtbo: Warning (unit_address_vs_reg): Node /fragment@1/__overlay__/trips/trip-point@0 has a unit name, but no reg property rpi-poe.dtbo: Warning (unit_address_vs_reg): Node /fragment@1/__overlay__/trips/trip-point@1 has a unit name, but no reg property rpi-poe.dtbo: Warning (unit_address_vs_reg): Node /fragment@1/__overlay__/trips/cpu_hot@0 has a unit name, but no reg property pi@dtc1:~/fan-control

After copying it to the

/boot/overlays/

folder, after rebooting the PI the fan does nothing – not even when the temperature gets up above 65degC.

Additionally, after applying it, I ran dmesg -w and noticed that I’m now getting over-current warnings: I don’t have any devices plugged into the PI at all; its headless and I connect over SSH.

pi@dtc1:~ sudo dmesg -C pi@dtc1:~ dmesg -w
[   72.037711] usb 1-1-port2: over-current change
[   72.131720] usb 1-1.1-port2: over-current change
[   72.271588] usb 1-1-port3: over-current change
[   72.371592] usb 1-1.1-port3: over-current change
[   72.511585] usb 1-1-port4: over-current change
[   93.891759] usb 1-1.1-port2: over-current change
[   94.053660] usb 1-1-port2: over-current change
[   94.131606] usb 1-1.1-port3: over-current change
[   94.301594] usb 1-1-port3: over-current change
[   94.371595] usb 1-1.1-port2: over-current change

(this goes on and on and on...)

Any thoughts? Help!

Thanks!

因此決定先接通樹莓派『I2C-0』︰

BCM0(pin 27) 、 BCM1(pin 28) 也。

結果『履虎尾』，不能『開機』勒！！？？

於是乾脆拔除『跳線』、拆掉『風扇』電源，重歸 RPI + PoE HAT + SD 卡，測試『最短距離』 瞧瞧？？！！

※ 註︰驗證 USB Boot 不 work 在先☻

果然目睹 USB 裝置『群魔亂舞』現象呦★

PoE HAT – USB Ports not working – over-current

martinrowan

Tue Aug 21, 2018 10:10 pm

Hi, Just taken delivery of my official PoE-HAT and whilst I can now power the Pi on without the need for a separate micro USB PSU, it’s not exactly usable as the USB ports aren’t working.

Hardware:

  • Raspberry Pi 3 b+
  • Raspberry Pi PoE HAT
  • Cisco SG250-26HP POE Network Swich.

System:

  • Linux raspberrypi 4.14.62-v7+ #1134 SMP Tue Aug 14 17:10:10 BST 2018 armv7l GNU/Linux
  • Firmware:
    Aug 16 2018 17:30:30
    Copyright (c) 2012 Broadcom
    version 31e0613622dc2f2463bf3dd74e6c897d91201a4d (clean) (release)

On booting (without anything connected to the USB ports) the following is logged:

[   11.661117] Bluetooth: RFCOMM socket layer initialized
[   11.661151] Bluetooth: RFCOMM ver 1.11
[   12.986076] usb 1-1.1-port2: over-current change
[   13.147084] usb 1-1-port2: over-current change
[   13.231877] usb 1-1.1-port3: over-current change
[   13.391693] usb 1-1-port3: over-current change
[   13.631851] usb 1-1-port4: over-current change
[   33.978119] usb 1-1.1-port2: over-current change
[   34.139091] usb 1-1-port2: over-current change
[   34.211769] usb 1-1.1-port3: over-current change
[   34.371756] usb 1-1-port3: over-current change
[   34.611750] usb 1-1-port4: over-current change
[  408.250020] usb 1-1.1-port2: over-current change
[  408.411057] usb 1-1-port2: over-current change
[  408.482948] usb 1-1.1-port3: over-current change
[  408.644602] usb 1-1-port3: over-current change
[  408.762133] usb 1-1.1-port2: over-current change
[  408.883014] usb 1-1-port4: over-current change
[  408.993105] usb 1-1.1-port3: over-current change
[  409.132964] usb 1-1-port2: over-current change
[  409.232949] usb 1-1.1-port2: over-current change
[  409.372938] usb 1-1-port3: over-current change

When connecting any USB device, a USB mass storage device or the Logitech wireless keyboard transceiver, messages are logged.

[  473.733117] usb 1-1.3: new high-speed USB device number 5 using dwc_otg
[  473.864020] usb 1-1.3: New USB device found, idVendor=0781, idProduct=556c
[  473.864035] usb 1-1.3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[  473.864043] usb 1-1.3: Product: Firebird USB Flash Drive
[  473.864051] usb 1-1.3: Manufacturer: SanDisk
[  473.864060] usb 1-1.3: SerialNumber: 4C532000000116109085
[  473.868191] usb-storage 1-1.3:1.0: USB Mass Storage device detected
[  473.871816] scsi host0: usb-storage 1-1.3:1.0
[  473.947128] usb 1-1-port2: over-current change
[  474.042110] usb 1-1.1-port2: over-current change
[  474.183449] usb 1-1-port3: over-current change
[  474.273351] usb 1-1.1-port3: over-current change
[  474.423299] usb 1-1.3: USB disconnect, device number 5
[  474.753127] usb 1-1.3: new high-speed USB device number 6 using dwc_otg
[  474.883976] usb 1-1.3: New USB device found, idVendor=0781, idProduct=556c
[  474.883993] usb 1-1.3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[  474.884001] usb 1-1.3: Product: Firebird USB Flash Drive
[  474.884009] usb 1-1.3: Manufacturer: SanDisk
[  474.884017] usb 1-1.3: SerialNumber: 4C532000000116109085
[  474.884822] usb-storage 1-1.3:1.0: USB Mass Storage device detected
[  474.885225] scsi host0: usb-storage 1-1.3:1.0
[  474.885928] usb 1-1-port4: over-current change
[  475.066003] usb 1-1.1-port2: over-current change
[  475.123277] usb 1-1-port2: over-current change
[  475.303252] usb 1-1.1-port3: over-current change
[  475.363319] usb 1-1-port3: over-current change
[  475.603178] usb 1-1.3: USB disconnect, device number 6
[  475.903134] usb 1-1.3: new high-speed USB device number 7 using dwc_otg
[  476.044024] usb 1-1.3: New USB device found, idVendor=0781, idProduct=556c
[  476.044042] usb 1-1.3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[  476.044050] usb 1-1.3: Product: Firebird USB Flash Drive
[  476.044059] usb 1-1.3: Manufacturer: SanDisk
[  476.044067] usb 1-1.3: SerialNumber: 4C532000000116109085
[  476.044877] usb-storage 1-1.3:1.0: USB Mass Storage device detected
[  476.048170] scsi host0: usb-storage 1-1.3:1.0
[  476.049075] usb 1-1-port4: over-current change
[  476.283387] usb 1-1-port2: over-current change
[  476.346097] usb 1-1.1-port2: over-current change
[  476.523476] usb 1-1-port3: over-current change
[  476.583383] usb 1-1.1-port3: over-current change
[  476.763258] usb 1-1.3: USB disconnect, device number 7
[  477.103133] usb 1-1.3: new high-speed USB device number 8 using dwc_otg
[  477.234021] usb 1-1.3: New USB device found, idVendor=0781, idProduct=556c
[  477.234038] usb 1-1.3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[  477.234047] usb 1-1.3: Product: Firebird USB Flash Drive
[  477.234056] usb 1-1.3: Manufacturer: SanDisk
[  477.234064] usb 1-1.3: SerialNumber: 4C532000000116109085
[  477.234868] usb-storage 1-1.3:1.0: USB Mass Storage device detected
[  477.237752] scsi host0: usb-storage 1-1.3:1.0
[  477.238749] usb 1-1-port4: over-current change
[  478.314404] scsi 0:0:0:0: Direct-Access     SanDisk  Ultra            1.26 PQ: 0 ANSI: 5
[  478.316594] sd 0:0:0:0: [sda] 31266816 512-byte logical blocks: (16.0 GB/14.9 GiB)
[  478.317631] sd 0:0:0:0: [sda] Write Protect is off
[  478.317649] sd 0:0:0:0: [sda] Mode Sense: 43 00 00 00
[  478.318064] sd 0:0:0:0: [sda] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
[  478.331456]  sda: sda1
[  478.334032] sd 0:0:0:0: [sda] Attached SCSI removable disk
[  478.340700] sd 0:0:0:0: Attached scsi generic sg0 type 0
[  478.394088] usb 1-1.1-port2: over-current change
[  478.555097] usb 1-1-port2: over-current change
[  478.633379] usb 1-1.1-port3: over-current change
[  479.183155] usb 1-1.3: reset high-speed USB device number 8 using dwc_otg
[  479.313802] usb 1-1-port3: over-current change
[  479.553522] usb 1-1-port4: over-current change
[  479.674094] usb 1-1.1-port2: over-current change
[  479.793515] usb 1-1-port2: over-current change
[  479.913413] usb 1-1.1-port3: over-current change
[  480.153155] usb 1-1.3: reset high-speed USB device number 8 using dwc_otg
[  480.283764] usb 1-1-port3: over-current change
[  480.442136] usb 1-1.1-port2: over-current change
[  480.603102] usb 1-1-port2: over-current change
[  480.673471] usb 1-1.1-port3: over-current change
[  481.153129] usb 1-1.3: reset high-speed USB device number 8 using dwc_otg
[  481.283588] usb 1-1-port3: over-current change
[  481.533586] usb 1-1-port4: over-current change

Checking my Cisco SG250-26HP switch shows the port connected to the Pi (via a 1m cable):

  • Operational Status: Delivering Power
  • Administrative Power Allocation: 30000mW
  • Power Consumption: 3000mW
  • Class: 3
  • PoE Standard: 802.3 AT

Do I have a faulty HAT, or RPi3, or any other suggestions as to why this isn’t working properly. When powered via micro USB power socket the USB ports work just fine.

………