BMD200 UART RX Problem

[Reuben]

On the BMD200 evaluation kit (www.rigado.com/.../) using the nrf58001:

--> UART TX (pin P0.09) works - confirmed with logic analyzer and Serial Port Terminal on the PC.

--> However, the RX pin is held HIGH (3.3V) and even when data is sent from the PC to the BMD200, no data is seen on the RX line, confirmed with the logic analyzer.

I tried the uart_pca10028 example and tried different settings with regards to the Hardware Flow Control Settings (both Enabled and Disabled, same problem, TX works, RX cannot see any data because it is held High). I also tried setting the RX pin as an input just in case it was not being set correctly through the libraries to no avail. The FT232 converter that I have connected to the TX and RX pins is working well on both lines, verified using the logic analyzer. Since the RX pin is held high, when TX_FOCA is connected to RX_BMD200, no data can be seen on the analyzer.

Any idea of what the problem might be? Any help and suggestions appreciated, thank you.

[Einar Thorsrud]

I would not expect the RX pin to be held high. If you use the UART driver, as is done in the UART Example, the RX pin is configured with pull resistors disabled (no pull). You can see this in line 80 in \components\drivers_nrf\uart\nrf_drv_uart.c.

[Eric Stutzenberger]

Hi Reuben,

• Full disclosure: I work for Rigado *

I sometimes have issues with the JLink Passthrough CDC UART driver. For some versions of the JLink driver, it seems to require the RTS pin to change states before it will enable the RX line. One option to solve this is to enable hardware flow control in your terminal application. Another option is to cut the traces on pins P0.09 and P0.10 and connect to a different UART device such as an FTDI board.

Hope this helps,

Eric