topic Re: S32K146EVB: How does the UART flow control work for the OpenSDA USB? in S32K

S32K146EVB: How does the UART flow control work for the OpenSDA USB?

mikesfn — Mon, 13 Jul 2020 20:45:40 GMT

This is probably more of a general configuration issue than a EVB issue. I am using the S32K146EVB and UART1 (which is connected on the OpenSDA USB port). On Windows 10, I am able to open the virtual COM port and send data to the EVB over UART and received data as well. However, I have now tried the same software on a different PC which happens to be running Windows 7 instead and the terminal no longer receives the UART data sent by the EVB.

The terminal I use on the PC is RealTerm. I am still able to open the COM port and send data to the EVB. I can debug the program and I see that the EVB receives the data and at least attempts to send the response. However, no data is received by the terminal. I tried re-installing the PEMicro drivers to see if that changed anything but it did not. The only difference I have noticed between the Windows 10 and Windows 7 environments is in the hardware flow control detected by RealTerm. When I open the COM port in Windows 10, it shows that the CTS, DCD, and DSR pins are all asserted. However, when I open the COM port in Windows 7, only the CTS pin is asserted. All of these pins are input flow control from the device to the PC, so I don't understand why they would be different between the 2 environments.

What could the issue be?

Re: S32K146EVB: How does the UART flow control work for the OpenSDA USB?

mikesfn — Mon, 13 Jul 2020 21:46:21 GMT

As an addendum: I have scoped the RXD and TXD pins (PTC6 and 7 for LPUART1 on the EVB) and I can see clearly that the RS-232 data is being received and transmitted on LPUART1, but for some reason the data transmitted by the EVB is not received by the PC.

Re: S32K146EVB: How does the UART flow control work for the OpenSDA USB?

dianabatrlova — Wed, 15 Jul 2020 09:46:51 GMT

Hello Michael,

Have you tried to reinstall the Realterm?

I would like to suggest trying to use another terminal, for example, Tera Term to check if the issue is not in the terminal.

Best regards,

Diana

Re: S32K146EVB: How does the UART flow control work for the OpenSDA USB?

mikesfn — Tue, 21 Jul 2020 20:11:03 GMT

I have tried several other serial monitors on the same PC with no luck. I tried a few other PCs, and it works fine.

The issue appears to be something specific to the Windows COM port drivers on this one PC, like some security setting that is blocking Rx flow control. I will have to dig deeper, but as this is not a problem with the OpenSDA firmware as I initially suspected I will close the topic.

Thanks