HAT not detected - EEPROM possibly corrupt?

@CFSworks wrote:

Hello all!

Recently while trying to troubleshoot the IMUs on my Navio2, I found emlidtool was not detecting the HAT anymore.

pi@navio:~ $ sudo emlidtool
emlidtool version: 1.0.0
Vendor: ¯\_(ツ)_/¯ Unknown, but most likely Emlid
Product: Seems like you booted without Navio properly screwed!
Issue: Emlid 2017-09-22 94b6586ea415c117b57d0d9eed9fc2df0bf1bcfd
Kernel: 4.9.45-94f47ec-emlid-v7+
emlidtool -h to get more help

I confirmed that the HAT part of the device tree wasn’t showing up:

pi@navio:~ $ ls /proc/device-tree/
#address-cells  clocks              fixedregulator_5v0  memreserve     serial-number  system
aliases         compatible          interrupt-parent    model          #size-cells
axi             cpus                leds                name           soc
chosen          fixedregulator_3v3  memory              __overrides__  __symbols__
pi@navio:~ $ stat /proc/device-tree/hat/
stat: cannot stat '/proc/device-tree/hat/': No such file or directory
pi@navio:~ $ stat /proc/device-tree/hat/product
stat: cannot stat '/proc/device-tree/hat/product': No such file or directory
pi@navio:~ $ stat /proc/device-tree/hat/vendor
stat: cannot stat '/proc/device-tree/hat/vendor': No such file or directory

I also tightened all of the screws. No dice. (And it’s on the Pi3 very snug as it is.)

To check the I2C bus, I turned on i2c_vc=on and rebooted and can see that the EEPROM is definitely there:

pi@navio:~ $ sudo i2cdetect -y 0
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: 50 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
pi@navio:~ $ sudo i2cdump -y 0 0x50 i
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f    0123456789abcdef
00: 00 02 00 69 00 00 00 01 00 00 00 2d 00 00 00 db    .?.i...?...-...?
10: c9 e0 f0 21 ae 44 ae 25 41 d2 51 e6 16 8b 0f 03    ???!?D?%A?Q?????
20: 00 01 00 0e 07 45 6d 6c 69 64 20 4c 69 6d 69 74    .?.??Emlid Limit
30: 65 64 20 4e 61 76 69 6f 20 32 62 4b 02 00 01 00    ed Navio 2bK?.?.
40: 20 00 00 00 00 02 00 00 00 00 00 00 00 00 00 00     ....?..........
50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
60: 00 00 6d 6d ff ff ff ff ff ff ff ff ff ff ff ff    ..mm............
70: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
90: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
a0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
b0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
c0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
d0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
e0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
f0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................

100 bytes seems oddly short for a dtb. Does the Navio2 EEPROM only store the product/vendor strings? Or did I somehow corrupt/truncate my EEPROM? I don’t have a copy of the known-valid EEPROM data - could anybody with a working Navio2 share the proper EEPROM contents? Does someone with better HAT expertise have any insights as to what causes the Raspberry Pi bootloader not to populate the /hat node?

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