voxl-uart-loopback problems

relevinsky · 24 Nov 2021, 10:09

Hi,

I run into the problem with voxl-uart-loopback on baud rate (921600) and buffer size >= 500 bytes. many times the loopback returns 0 bytes (on reading part). If i set low baud rate 9600 and 200 bytes of data, its FAIL always on reading.![alt text]( image url) . Please help me . It's not a regular serial,it works with DSP via RPC. So i need to be sure that will not be a problem with data integrity.Thanks.

Alex Kushleyev · 24 Nov 2021, 22:50

Hello,

There were a few issues with the uart loopback example:

the test buffer size was not handled properly (if test size is larger than HelloWorld strin
the sleep time was not enough to allow the transfer to happen (the write function is non-blocking, it seems)

I have made some fixes here:
https://gitlab.com/voxl-public/core-libs/libvoxl_io/-/blob/dev/lib/apps/voxl-uart-loopback.c

Now the behavior is as shown below.. please try it.

./voxl-uart-loopback -d 7 -b 9600 -s 20
INITIALIZING
Sending 20 bytes:
0123456789:;<=>?@ABC
Transfer should take ~20833us, sleeping for 25833us (+5000us overhead)
Reading back data...
Received 20 bytes:
0123456789:;<=>?@ABC
closing uart bus
PASS

./voxl-uart-loopback -d 7 -b 9600 -s 500
INITIALIZING
Sending 500 bytes:
0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789:;<=>?@ABCDEFGHIJ
Transfer should take ~520833us, sleeping for 525833us (+5000us overhead)
Reading back data...
Received 500 bytes:
0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789:;<=>?@ABCDEFGHIJ
closing uart bus
PASS