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Serial input on ls1021a-twr lags after copy & paste

Question asked by mo rooholamini on Oct 25, 2017
Latest reply on Nov 6, 2017 by Pavel Chubakov

After sending data  from the Linux host to the target through UART, return data from the target could start lagging by one or more characters. For example,  say, out of 180 characters sent only 178 characters return from the target and the next two keystrokes (any) on the serial console sends the two keystrokes to the target  immediately, but the target returns chars 179 and 180 to the host instead.  From this point on for any keystroke,  what the target returns is from the two keystrokes ago.  In the sample debug output below, keystroke 'd' is sent to the target immediately, but the target returns 'k' that was 2 keystrokes ago.

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Sample debug output:

Frame to be sent to target (stdin -> serial): ' d '
Frame sent (stdin -> serial)): ' d '
Payload coming from ls1 on the serial: ' k '

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We have verified our serial application puts data on the serial device correctly. We have also verified there is no data in the fifo when this issue occurs.  Cycling power on the board does not fix the problem, as power is still supplied to the UART/MBED through the host. The only way to get back to a steady state is to unplug and plug back the usb cable at J5. 

 

U-Boot 2015.04-dirty (Sep 14 2016 - 10:35:24)

Host: Ubuntu-16.04

 

Thank You for any help

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