假使有 ID EEPROM 軟體解碼工具，解讀 test.eep

pi@raspberrypi:~/hats/eepromutils 

 

自然輕鬆快意！！既使沒有 ID EEPROM 軟體解碼工具，閱讀文件

B+ HAT ID EEPROM FORMAT SPECIFICATION

CURRENTLY THIS SPEC IS PRELIMINARY AND THEREFORE STILL LIKELEY TO CHANGE

Note that there are software tools for creation of EEPROM images and for flashing / dumping images from attached HATs.

EEPROM Structure

  HEADER  <- EEPROM header (Required)
  ATOM1   <- Vendor info atom (Required)
  ATOM2   <- GPIO map atom (Required)
  ATOM3   <- DT blob atom (Required for compliance with the HAT specification)
  ...
  ATOMn

EEPROM Header Structure

  Bytes   Field
  4       signature   signature: 0x52, 0x2D, 0x50, 0x69 ("R-Pi" in ASCII)
  1       version     EEPROM data format version (0x00 reserved, 0x01 = first version)
  1       reserved    set to 0
  2       numatoms    total atoms in EEPROM
  4       eeplen      total length in bytes of all eeprom data (including this header)

Atom Structure

  Bytes   Field
  2       type        atom type
  2       count       incrementing atom count
  4       dlen        length in bytes of data+CRC
  N       data        N bytes, N = dlen-2
  2       crc16       CRC-16-CCITT of entire atom (type, count, dlen, data)

Atom Types

  0x0000 = invalid
  0x0001 = vendor info
  0x0002 = GPIO map
  0x0003 = Linux device tree blob
  0x0004 = manufacturer custom data
  0x0005-0xfffe = reserved for future use
  0xffff = invalid

Vendor info atom data (type=0x0001):

Note that the UUID is mandatory and must be filled in correctly according to RFC 4122 (every HAT can then be uniquely identified). It protects against the case where a user accidentally stacks 2 identical HATs on top of each other – this error case is only detectable if the EEPROM data in each is different. The UUID is also useful for manufacturers as a per-board ‘serial number’.

  Bytes   Field
  16      uuid        UUID (unique for every single board ever made)
  2       pid         product ID
  2       pver        product version
  1       vslen       vendor string length (bytes)
  1       pslen       product string length (bytes)
  X       vstr        ASCII vendor string e.g. "ACME Technology Company"
  Y       pstr        ASCII product string e.g. "Special Sensor Board"

GPIO map atom data (type=0x0002):

GPIO map for bank 0 GPIO on 40W B+ header.

NOTE GPIO number refers to BCM2835 GPIO number and NOT J8 pin number!

  Bytes   Field
  1       bank_drive  bank drive strength/slew/hysteresis, BCM2835 can only set per bank, not per IO
            Bits in byte:
            [3:0] drive       0=leave at default, 1-8=drive*2mA, 9-15=reserved
            [5:4] slew        0=leave at default, 1=slew rate limiting, 2=no slew limiting, 3=reserved
            [7:6] hysteresis  0=leave at default, 1=hysteresis disabled, 2=hysteresis enabled, 3=reserved
  1       power
            [1:0] back_power  0=board does not back power Pi
                              1=board back powers and can supply up to 1.3A to the Pi
                              2=board back powers and can supply up to 2A to the Pi
                              3=reserved
                              If back_power=2 high current USB mode is automatically enabled.
            [7:2] reserved    set to 0
  28      1 byte per IO pin
            Bits in each byte:
            [2:0] func_sel    GPIO function as per FSEL GPIO register field in BCM2835 datasheet
            [4:3] reserved    set to 0
            [6:5] pulltype    0=leave at default setting,  1=pullup, 2=pulldown, 3=no pull
            [  7] is_used     1=board uses this pin, 0=not connected and therefore not used

Device tree atom data (type=0x0003):

Binary data (DT blob fragment for board hardware).

For more information on the Devicetree atom contents, see the Devicetree Guide.

 

，手動解碼也許學的更多？？

由於 hexdump 不是以 byte 為單位，故而不如 hexedit 方便也。

sudo apt-get install hexedit

 

解碼結果如下︰

EEPROM Header
【4 signature】 52 2D 50 69 [R-Pi]
【1 version】 01
【1 reserved】 00
【2 numatoms】 02 00
【4 eeplen】 79 00 00 00

ATOM1
【2 type】 01 00 [vendor info]
【2 count】 00 00
【4 dlen】 3D 00 00 00
[N data]
【16 uuid】 3D F8 93 7E 6A 21 78 B5 D2 46 D9 C7 30 E2 2A 62
【2 pid】 41 31 [A 1]
【2 pver】 01 00
【1 vslen】 17
【1 pslen】 0E
【X vstr】 48 69 46 69 42 65 72 72 79 20 28 4D 6F 64 75 6C 20 39 20 4C 4C 43 29 [HiFiBerry (Modul 9 LLC)]
【Y pstr】 48 69 46 69 42 65 72 72 79 20 44 41 43 2B [HiFiBerry DAC+]
【2 crc16】 4B E8

ATOM2
【2 type】 02 00 [GPIO map]
【2 count】 01 00
【4 dlen】 20 00 00 00
[N data]
【1 bank_drive】 00
【1 power】 00
【28 1 byte per IO pin】 00 00 A4 [2] A4[3] 00 00 00 00 00 00 00 00 00 00 00 00 E0[16] 00 84[18] 84[19] 84[20] 84[21] 00 00 00 00 00 00
【2 crc16】 82 69

FF FF [invalid]

 

【參考資料】

 

 

聰明的人或許笑作者太癡，人工解碼幹嘛的呢！！明就有 eepdump 這麼好用的工具乎？？！！然而不能手動人工解碼，將如何寫作與除錯那個程式耶！！？？

pi@raspberrypi:~/hats/eepromutils ＄ ./eepdump test.eep test.txt
Reading atom 0…
CRC OK
Reading atom 1…
CRC OK
Warning: Dump finished before EOF
Warning: EOF does not match length specified in header
Done.
pi@raspberrypi:~/hats/eepromutils ＄ cat test.txt
# ———- Dump generated by eepdump handling format version 0x01 ———-
#
# –Header–
# signature=0x69502d52
# version=0x01
# reserved=0
# numatoms=2
# eeplen=121
# ———-
# Start of atom #0 of type 0x0001 and length 61
# Vendor info
product_uuid 622ae230-c7d9-46d2-b578-216a7e93f83d
product_id 0x3141
product_ver 0x0001
vendor “HiFiBerry (Modul 9 LLC)” # length=23
product “HiFiBerry DAC+” # length=14
# End of atom. CRC16=0xe84b
# Start of atom #1 of type 0x0002 and length 32
# GPIO map info
gpio_drive 0
gpio_slew 0
gpio_hysteresis 0
back_power 0
# GPIO FUNCTION PULL
# —- ——– —-
setgpio 2 ALT0 UP
setgpio 3 ALT0 UP
setgpio 16 INPUT NONE
setgpio 18 ALT0 DEFAULT
setgpio 19 ALT0 DEFAULT
setgpio 20 ALT0 DEFAULT
setgpio 21 ALT0 DEFAULT
# End of atom. CRC16=0x6982
pi@raspberrypi:~/hats/eepromutils ＄