piSerial fails with getSerNum() -1

[jenskastensson]

Hi,

how can I troubleshoot this issue:

1. flash a device with a new image
2. piSerial -s returns "getSerNum failed -1"

I dont have the original image so I cannot reverse.
Kindly
Jens

[lukas]

Usually this happens because the crypto chip on the i2c-1 bus is inaccessible.

Is this on a RevPi Core or Connect?
Are you using the original RevPi image?
Could you doublecheck if /boot/config.txt contains the line "dtoverlay=i2c1-bcm2708,sda1_pin=44,scl1_pin=45,pin_func=6"?
If you type "i2cdetect -l", is the i2c-1 bus listed?
If you type "i2cdetect 1", are devices 51 and 60 found on the bus?
If you invoke "piSerial" on the command line, do you get the error message as well?

Note: You can get past the factory reset on first login by pressing Ctrl+C (in order to enter the above-mentioned commands).

[jenskastensson]

After flashing the RevPi Core device (using an image file that has been confirmed good with 20 other devices) two devices fails.
The /boot/config.txt is empty.
The output from the commands, see screenshot:


Please advise,
Jens

[dirk]

Hi Jens,
first of all it is suspicious that only some of the flashed devices have an empty /boot/config.txt . This empty file leadas to the missing I2C device nodes on the system.
The empty file may be the result of an immediate powercycle after the script revpi-factory-reset tries to write the MAC address to this file.
(The script revpi-factory-reset is automatically called after the first login on a fresh system and writes the MAC and the default password.)
Then the filesystem driver is unable to flush the changes.
So you could try to write the image again or you can just copy the /boot/config.txt from another device and adapt the MAC address accordingly.