nrf51822 uart only works when connected to debugger

RE: nrf51822 uart only works when connected to debugger

Simon — Mon, 03 Dec 2018 09:10:38 GMT

I am happy you figured it out, and glad to help. Please ask if you encounter any more problems.

RE: nrf51822 uart only works when connected to debugger

JonesNg — Thu, 29 Nov 2018 08:15:49 GMT

Hi Simon,

I noticed that the wire between the uart to usb dongle and the module was damaged. Therefore, the dongle needs the DK to complete the circuitry so as to read the uart signal correctly.

After changing the wiring, the uart message can be seen without connected to the DK.

Thanks for you help.

RE: nrf51822 uart only works when connected to debugger

JonesNg — Thu, 29 Nov 2018 01:20:03 GMT

Here are the answers of the questions:

I connect the VTG, SWDIO, SWDCLK AND GND from P20 of the nrf51 DK to VCC (3.3V), SWDIO, SWDCLK and GND to the module.
I use an connect UART TX, UART RX and GND to a uart to usb dongle and display the message in PC using a serial tool.
I am using a module with nrf51822AA with external crystal of 16MHz and 32.768KHz.

RE: nrf51822 uart only works when connected to debugger

Simon — Wed, 28 Nov 2018 13:43:44 GMT

I have some questions first:

How do you connect your module to the DK?
How do you read the UART messages?
Are you using an external crystal? By default, the UART will use the RC oscillator (see page 28 in nRF51822, Product Specification v3.3 ), which has a high tolerance.

Best regards,

Simon