nRF9160 DK as a Debugger for a second nRF9160 DK

[RodWatt]

Hi,

I plan to design my own hardware based around nRF9160. Prior to this, I want to verify that I can use the nRF9160DK as a debugger for my own board. As an initial test, I plan to use two nRF9160 DK boards, one as a target and one as a debugger. I would like to verify the set up for this please.

On the "debugger" nrf9160DK, I connect a USB cable into J4.

I connected a 10pin cable from P22 (Debug Out) on the debugger board into P3 (nrf91 Debug in) on the target board. 

On the target board, I select "nRF only" via SW1.

Connect a second USB cable to J4 on the target board. This will provide power and VCOM on the target board.

So, I have three questions. 

1. Are my connections above correct?

2. Are there any other switches or settings I need to adjust

3. With only the target board connected to the PC, and SW1, nRF ONLY selected, I don't see any serial data over the USB connector.  I know my code is running, as it toggles a GPIO pin which I can monitor. Where is the serial port visible when the target is in nrf only mode? 

Thanks,

Rod

[Joakim Jakobsen]

Hi Rod. 

I believe this should work. 

Your connections looks to be correct. Could you also set the "VDD IO" to "3V" as shown in the picture below and see if that helps: 

Regards, 
Joakim Jakobsen

[RodWatt]

Hi Joakim,

I have now received my second board and have configured them as detailed above. This now allows me to program my target nRF9160DK from my debugger nRF9160 which is great.

I still am having problems seeing my serial output from the target board. When I have "nRF Only" switched to off on the target board, I see 3 possible serial terminals

Watts-MacBook-Pro:~ Watt$ ls /dev/cu*

/dev/cu.Bluetooth-Incoming-Port /dev/cu.usbmodem0009600405783

/dev/cu.usbmodem0009600405781 /dev/cu.usbmodem0009600405785

I can then see the serial output via the command

Watts-MacBook-Pro:~ Watt$ screen /dev/cu.usbmodem0009600405781 115200 -L

However, when I switch it to "nRF Only", all I see is

Watts-MacBook-Pro:~ Watt$ ls /dev/cu*

/dev/cu.Bluetooth-Incoming-Port

So my question is, where can I see the serial output on my target board when I switch it to "nRF Only"?

Regards,
Rod

[RodWatt]

Hi Joakim,

I have had another look at this. I imagine the reason I am not seeing the terminal out put is due to the way the VCOM is being routed. As a quick and easy test, I tried to connect up directly to the UART port using a UART - USB adapter.

https://www.amazon.co.uk/gp/product/B01N4X3BJB?pf_rd_p=330fbd82-d4fe-42e5-9c16-d4b886747c64&pf_rd_r=BVBRX27PHHRS1DA3SM0N

Looking at the overlay file in the secure_boot application, I note that TXD and RXD are connected to pins 18 & 17.

/* needed to get the NRF_UARTE2 defined */
&uart2 {
	current-speed = <1000000>;
	status = "ok";
	tx-pin = <18>;
	rx-pin = <17>;
	rts-pin = <19>;
	cts-pin = <21>;
};

&spi3 {
	status = "ok";
	sck-pin = <10>;
	mosi-pin = <11>;
	miso-pin = <12>;
	ss-pin = <13>;
	spi-max-frequency = <4000000>;
};

Unfortunately, this did not work.

Any thoughts as to why I am not seeing thermal output when I switch the board to nRF Only mode?

Thanks,

Rod

[RodWatt]

PS, I also noted in the UM that UART was routed too P0.28 & P0.29. I also tried connecting directly to these pins

[RodWatt]

PPS 

Followed this as well, no luck

https://devzone.nordicsemi.com/f/nordic-q-a/44114/continuous-wave-for-nrf9160

[RodWatt]

Hi Joakim,

Ok, I now have this working, almost. 

I followed this link

https://devzone.nordicsemi.com/f/nordic-q-a/44114/continuous-wave-for-nrf9160

and I had to change the I/O pins used but this now seems to work.

I have a couple more quick questions and then I think we can close this 

1. Please can you confirm what I/O pins are not used on the DK and are free? I recall seeing a list somewhere but I can't find it.

2. On my target board, where I am running in "nRF only mode", I assume that I should now be able to more or less use any I/O pin I want on the 9160? I have tried to use various pins for my UART Tx/Rx but only a handful seem to be usable, even in nRF Only mode. Do I need to program the nRF52840 first to free up I/O pins on the 9160?  

Regards,

Rod

[Joakim Jakobsen]

Hi Rod! 

I'm glad you were able to make it work.

1. You can find the list of which I/O pins are free to use in the Pin Assignments in the nRF9160 PS. 

2. When using nRF Only mode the UART are routed to VCOM 0,1,2. So if you want to to use the UART while in nRF Only mode, you can take a look at the suggestion from my colleague Martin in the thread below: 
https://devzone.nordicsemi.com/f/nordic-q-a/45476/connecting-uart1-to-a-periph-on-nrf9160-dk 

Best regards, 
Joakim.

[RodWatt]

Hi Joakim,

Thanks for this. I am still seeing problems accessing these pins. For example, in the link above,  Pin Assignments , it suggested P0.08 and P0.09 are available as GPIO however, when I try to use these pins as a UART, I update my overlay file accordingly, they don't work. Its as if the DK is using these as something else and they are not free. 

Rod