Queries and Programing Interface for nRF52840 custom Board

[Moghees]

We want to use nRF52840 SoC as our controller in our custom Board. I have reviewed the product specification document of nrf52840. I have following queries:

1. Is High Voltage mode only used when we want to operate nRF52840 SoC with Li-Po Batteries or 5V DC source directly?
2. Is there any other use of High Voltage Mode?
3. In Normal Voltage mode can we run nRf52840 SoC with 3.6V DC source?
4. For programing custom nRF52840 board using nRF52840 DK, we have to supply VDD pin on custom board with 3.0V?
5. Is the below mention block diagram for programing nRF52840 custom board using nRF52840 DK correct?

Regards,

Moghees Bin Zahid

[Jared]

Hi,

• Is High Voltage mode only used when we want to operate nRF52840 SoC with Li-Po Batteries or 5V DC source directly?

 High voltage mode is used when the voltage of your supply is outside the operating region of normal mode or you want to supply an external device from VDD

• Is there any other use of High Voltage Mode?

 See my previous answer.

• In Normal Voltage mode can we run nRf52840 SoC with 3.6V DC source?

 Yes, but it's right at the limit. Might be better to just use High voltage mode if the voltage isn't exactly 3V6 but maybe a bit higher. 

• For programing custom nRF52840 board using nRF52840 DK, we have to supply VDD pin on custom board with 3.0V?

 Yes, the board has to be supplied with 3V0. That's the only voltage supported by the onboard debugger. 

1. Is the below mention block diagram for programing nRF52840 custom board using nRF52840 DK correct?

 Yupp pretty much.

regards

Jared 

[Moghees]

Thanks for the reply. If we want to use High Voltage mode. Then In order to program custom board, we should connect VDD of DK with VDDH pin of custom board? Is there any other difference in connection for nRF52840 SoC used in high voltage mode

[Jared]

What voltage do you want the board to run at in high voltage mode? 

[Moghees]

We want to run board at 5V. Just to clarify my question I want to know how to program our custom Board if we want to run nRF52840 custom board in high voltage mode  

[Jared]

Hi,

If you want to program a board that runs on 5V then the sketch that you shared is not correct. The interface only supports 3V. You can try:

1. Supply the custom board with 5 V at VDDH
2. Change REG0 output so that the VDD voltage is 3V. Default is 1V8
3. Connect VTG to VDD on the nRF52840 board
4. SWDIO and SWDCLK and GND should be connected as before

It is the output from REG0 which decides the VDD voltage which is what relevant for the SWD programming.

regards

Jared

[Moghees]

Sorry for late reply and Thanks for the reply. So if we are using nRF52840 SoC in low power mode and at 3V, than above diagram that I have attach with question is correct?
For first time we have to program it to change value of REG0
I have read following link from Nordic Q/A page programing nRF52840 SoC in High Voltage Mode. In this page it says we have to program once nRF52840 SoC to change value of REG0. To change value of REG0 we have to supply directly to VDD and change REG0 output to 3V. After that we can program our SoC in High Voltage mode by attaching VDD to VTG. So I want to ask can we directly supply voltage at VDD if we are using it in high voltage mode?

Regards,

Moghees

[Jared]

Moghees said:

So if we are using nRF52840 SoC in low power mode and at 3V, than above diagram that I have attach with question is correct?

 And in Normal voltage mode, Yes correct.

 

Moghees said:

I have read following link from Nordic Q/A page programing nRF52840 SoC in High Voltage Mode. In this page it says we have to program once nRF52840 SoC to change value of REG0. To change value of REG0 we have to supply directly to VDD and change REG0 output to 3V. After that we can program our SoC in High Voltage mode by attaching VDD to VTG. So I want to ask can we directly supply voltage at VDD if we are using it in high voltage mode?

 No!!! In high voltage mode, VDD is an output. You should therefore never supply it in high voltage mode. Note the answer from the Nordic engineer says: 

• Make a debugger adapter that shorts VDDH and VDD if VDDH < 3.9V.

Shorting VDDH and VDD will put the nRF into normal mode, thus making VDD an input.

I think what you should do is to get a stand alone debugger that supports programming at your intended voltage.

regards

Jared 

[Moghees]

Thankyou for the reply, So I should be using debugger that supports programing at 1.8V. If I am using nRF52840 SoC in High Voltage mode?
In order to program custom board we need to define custom_board.h and after that we can program soft device and our application code as well or do we need anything else?