Hello we are using the HL8548-G part in a custom design. In fact we have designed two boards with this part but we are only just starting to see this issue and we can reproduce it on both boards. We are connecting to the board from an IMX6 running Linux, although we have now repeated the problem connecting to the module using A host PC running Linux as well.
We started to notice the problem when our customer (who is developing the software) complained about the ttyACM0 connection being dropped and not being able to reconnect.
We can reproduce this by writing a small C program to open ttyACM0 device and send AT every ~100mS until it stops responding. it takes between 4000 and 12000 loops to fail. When it fails, the program can still ‘write’ data to the ACM driver but all reads fail with one of the following linux errors:
Error 22 invalid argument
Error 110 connection timed out
Interestingly we can then do the same test on another port, say ttyACM3 and the same failure occurs. we did the same on 4 & 5 as well.
Once the module is power cycled the problem has gone away.
We are using firmware version HL8548-G 22.214.171.124
I hope you can help, as we may have to consider selecting another module soon, which is costly