I setup NCP stack processor on the EFR32 wireless starter kit radio board and would like to connect to my custom board where NCP application runs. My problem is the custom board transmits EZSP packets but the radio board doesn't response at all. It works perfectly okay when it communicates to NCP host on linux instead of the custom board. I checked UART lines and found two useful links.
To speak conclusion, none of them worked for me. When I follow the steps in the second link, NCP host on linux worked okay / not okay depending on this line.
If ENABLE_VCOM is 1, NCP host on linux works okay, and it is 0, it doesn't. So I guess VCOM enable control through the pin PA5 works well. However, my custom board is still not working for either values of ENABLE_VCOM. I confirm that the UART on the custom board working fine, (115,200, n, 8, 1stop). The TX line issues few bytes at the very beginning, "1A C0 38 BC 7E", but nothing come up with RX line. (verified with oscilloscope) I connected 3 pins in the expansion header to the custom board, pin14/UART_RX, pin12/UART_TX and pin1/GND. And this is the hardware configurator setup after following the 2nd link. Please let me know if I am wrong or something to do more. Thanks.
Hi Hyeong KIM, first of all, the "VCOM enable pin" is used only on WSTK. This pin is connected to the mother board of the WSTK, and it controls whether the virtual COM port of the mother board should connected to the UART of the radio board or not. You can refer to the schematic of the mother board(BRD4001) for detail.
In your case, as you just connect tx/rx/gnd to your custom host board, you should set the flow control of the uart to "software flow control" or "None". It's recommended to use "software flow control". To do that, you need to select "ncp-uart-sw" when you create your ncp project, and in the properties of the USART, set the flow control to be "xon/xoff". Then when you start the host, you will also need to set the flow control to be "xon/xoff".