UART can send data while cann't receive data

[Alice]

Hi,

I'm using nRF5 SDK V12.0, I found a strange problem. That is the UART can send data to PC, but it cann't receive data from PC. However, this problem just arise on some PC, most of the PC wouldn't have the problem. To my surprise, no matter I use 51822 or 52832 to test on the PC, the problem will arise. The UART rate is 9600 and I test with PCA10028 and PCA10040 board. Is there internal pull-up resistor on the RX pin when it is set as UART function ?

I also use oscilloscope to compare the level of the TX pin between the good and bad PC when PC is sending data to 51822 or 52832, I found that it's the same.

[FormerMember]

On a "bad" PC, could you try a different terminal and check if that change anything?

[Alice]

Yes, I have try a different terminal, but it's the same problem.Ti or CSR bluetooth chip work well on the "bad" PC.

[FormerMember]

On a "bad" PC, is PCA10040 listed as a COM port?