Raspberry Pi 4 with Mesa 7c81

The


message is harmless is just means the RPIs SPI interface cannot do 32 bit transfers
so mesaflash uses 8 bit transfers instead

I dont know why readhmid is not working but note, you are not using the new configuration.
To test a new configuration that has been written to the fallback area of the EEPROM, you would:

That's what I did - it's my eighth line from the bottom.

root@raspicnc-7c81:~# mesaflash --device 7c81 --addr /dev/spidev0.0 --spi --reload

unable to set bpw32, fallback to bpw8
...

No, you did --reload , not --fallback --reload

-- reload by itself will load the FPGA from the user configuration area of the flash EEPROM
--fallback --reload will load the FPGA from the fallback area of the flash EEPROM

Ok - sorry. When I use --fallback --reload, I finally get a configuration listing.
After the restart, the configuration is finally listed normally, ie without the --fallback command, only readhmid.

Thank you, I really appreciate your help.

Note that if you have only loaded the 7i78 configuration in the fallback area
it will only be used if you load the FPGA from it with mesaflash --fallback --reload
and it will only persist until a power cycle. This makes it valuable for testing
unknown bitfiles. If the new bitfile works, then you can write it to the user configuration
area of the flash (no --fallback).

If you load a bad bitfile into the fallback area when testing,
make sure to re-write the falllback area with a working bitfile
(default is 7c81_fallback.bit)

The fallback configuration is used when the user configuration
fails to load because its corrupted in some way. For example
if you write a bitfile to the 7C81 and have a crash in the middle of
writing the flash, at the next power cycle, the FPGA will attempt
to load the user configuration but will fail (it will detect a CRC error)
In this case, the FPGA will attempt to load the fallback configuration
so it important to have a working fallback configuration in the EEPROM

Hello. Complete novice here.

I have gotten my hands on a 7C81 and I want to connect my closed loop steppers directly it.

From what I have seen on the fourms, this is a more unusual setup, and I will need to make and flash a custom bitfile to my board.
My understanding is that I will need PWM + 3StepGens + 3QCounts.

The -readhmid output from the default bitfile has one QCount with A, B, IDX, but my encoders have differential output. A+,A-,B+,B-
Is this something I can configure my custom bitfile to accept? Or will I need 6 QCounts and some software layer? Or simply ground the negatives? I saw that the 7i78 has accepts a differential encoder input.

Many thanks in advance.