chapter 6 can not get correct output, stuck at: [ML] Requesting binary

[Tim-C1]

I am using rasberry Pi 3a, the first 5 chapters are ok but I can not get correct ouput for chapter 6.
This is the result

I don't know where should I begin to debug, please help!

Oh, it also seems that I cannot echo input in Chapter5, I think that's because clear_rx or read_char is blocking

[SikkiLadho]

Were you able to fix this? I am still having this issue on rpi4.