Programming nRF52840 SOC with SWD

[Nikosant03]

Hi everyone,

I am developing a custom PCB that will integrate the nRF52840 SOC. More specifically I will use the MDBT50Q-1MV2 module from Raytac that is approved by Nordic.

I will program the chip with SWD. What I have understand so far is that four pins are required for programming and one pin to send data on serial monitor over UART.

To program:

1. VDD

2. SWCLK

3. SWDIO

4. GND

To serial print:

To serial print data (using printf) I have to use the SWO pin.

I am correct so far? SWO pin is enough for visualing data (e.g using PUTTY)?

I will use the J link EDU mini debbuger along with a 10pin IDC cable

Are these equipement enough for programming the nRF52840 IC?

I also noticed that there is a RESET pin on the 10pin SWD connector. I assume that this pin is to reset the nRF52840.

What is the purpose of this pin on the SDW connector? I mean, looking the J link EDU mini I cannot see any push botton connected on the RESET pin...

Lastly, this Link suggests that a 100k pull up resistor must be used with the SWDIO and a 100k pull down resistor must be used with the SWCLK.

Looking the schematic of nRF52840 Dev. Board I see that no pull up and pull down resistors are been used for SWDIO and SWCLK.

Should I use these resistors? Maybe they are included inside the MDBT50Q-1MV2 module?

Thanks in advance

Nick

[Amanda Hsieh]

Hi Nikos,

 

I am correct so far?

Yes, you should only need (SWDIO, SWCLK, VCC and GND) to program the device. Also remember to power your nRF52 device!

• VDD: Reference voltage for programmer
• SWDIO: Serial wire debug data
• GND: Ground
• SWDCLK: Serial wire debug clock

 

SWO pin is enough for visualing data (e.g using PUTTY)?

Will give complete answer next week.  

Are these equipement enough for programming the nRF52840 IC?

 Yes, you also could use nRF52840 DK to connect your custom board to debug. Please see Debug output.

 

What is the purpose of this pin on the SDW connector?

You don't need RESET pin to program/debug. You can do softreset if you don't have access to the RESET pin. RESET pin is optional on nRF52, you can actually disable RESET and use the pin as normal GPIO pin.

Should I use these resistors? Maybe they are included inside the MDBT50Q-1MV2 module?

 No, Please see Debug and trace/Electrical specification, nRF52840 already has internal SWDIO and SWDCLK pull up/down resistance. 

-Amanda H.

[Nikosant03]

Thank you Amanda for your assistance so far,

Sure, I will wait for your complete answer.

Nick