USB CDC ACM package errors

[Duy]

Hello Nordic Support,

I am using nRF52840 with SDK 15.3. I am running the USB CDC ACM in bulk transfer and interrupt. My nRF52840 plays the central role, it will send strings to the host when there are actions from the peripherals or it will execute commands from the host.

When using Windows (PC) or Linux (Raspberry Pi) to communicate with the nRF52840, I have below issues:

1. The first characters are always lost when sending from host. Exp: Host transfers: Hello from Duy\r\n; Device receives: ello from Duy\r\n.

2. Dummy characters. Exp: Host transfers: Hello from Duy\r\n; Device receives: ello from Duy\r\n\n or Host transfers: Hello from Duy 1000\r\n; Device receives: ello from Duy 100000\r\n\n.

Update: 3. There is no error in data from the nRF52840 to the host.

Can you help me analyze the cause and solutions for this? I also played around with other MCUs but these problems does not happens to them.

Thanks and best regards,

            Duy

[Susheel Nuguru]

Sorry for the late response.

I haven't heard of any packet losses issues before regarding this. So I am not sure what the issue is here. It looks like there is some sync issue rather than buffer issue. Can you help me replicate the problem?

[Duy]

Hi Susheel Nuguru,

Sorry for the late reply, I found that the problem was in software design, the interval between 2 packages are less than 1ms which causes data overlapping.