nRF51 DK UART to USB not working (Virtual COM port)

[Francesco Donadon]

Hi all,

I'm having problems into making the virtual COM port of the nRF51 DK work.

The only line in the User guide regarding it's configuration is the following:

"Note: The terminal used must send a DTR signal in order to configure the UART Interface MCU pins."

So what does it mean? Which signals after the DTR signal should I send to configure the baud rate exactly?

And what are the default parameters if I don't send anything and I just want it to work out of the box? I need to know them to configure the nrf UART in code.

I'm using Mac OS X, and when I plug the board the Virtual COM port is detected as /dev/(cu|tty).usbmodem14111. Do I need some driver?

Thanks for your help.

[Alex]

On nRF51 DK I used simple_uart.c with settings

#define RX_PIN_NUMBER  11
#define TX_PIN_NUMBER  9
#define CTS_PIN_NUMBER 10
#define RTS_PIN_NUMBER 8
#define HWFC           false

simple_uart_config(RTS_PIN_NUMBER, TX_PIN_NUMBER, CTS_PIN_NUMBER, RX_PIN_NUMBER, HWFC);

Default speed of Virtual COM port on PC is 38k without flow control. Speed defined in simple_uart_config()

[Francesco Donadon]

Thanks for the answer, but this is not working for me.

The board is showing as /dev/tty.usbmodem14111. I'm using Coolterm with the following settings:

Port: /dev/tty.usbmodem14111 Baudrate: 38400 Data bits: 8 Parity: none Stop bits: 1 Flow control: none checked Initial Line states: DTR On, RTS On

In the fw I am sending a line every second, yet nothing is printed on screen.

[Alex]

I'd check with oscilloscope signal at TX_PIN_NUMBER on DK. Same with RX_PIN_NUMBER while sending something from PC.

[RK]

have you tried /dev/cu.* instead? That's what I use, not /dev/tty. I used to know the difference but that knowledge is lost in the depths of time (and it's a shame anyone still has to know it).

[Francesco Donadon]

Great, using /dev/cu.* did the trick. Thank you!