nRF9160-DK: P15 Shield Debug (out) connector

[Smart.Enrg]

Hi,

I'm looking to use P15 (Shield Debug out connector) on nRF9160-DK. Description here https://infocenter.nordicsemi.com/index.jsp?topic=%2Fug_nrf91_dk%2FUG%2Fnrf91_DK%2Fhw_debug_out.html reads: 

"P15 can also be used as a debug out connector to program shield-mounted targets.

For both P22 and P15, the interface MCU will detect the supply voltage on the mounted shield and program/debug the target.

If the interface MCU detects target power on both P22 and P15, it will program/debug the target connected to P22 by default."

I'm bit confused -
1) if P15 can be used as a debug out connector to program shield-mounted targets, which signal/ pin on P15 is used to detect 
    external/ shield target voltage by internal MCU?

2) If I'm using only P15 to program shield, why does the interface MCU need to detect target power on BOTH P22 AND P15?
    Also, the last line in quoted description above says "it will program/debug the target connected to P22 by default." How can 
    I select P15 instead of P22 for program/ debug?

Please advise. Thanks.

Best,
SE

[Heidi]

Hi!

1) P15 PIN 3 SWD1_SELECT is the voltage supply from the external target, used as voltage detect input to the interface MCU, see here.

2) If you're only using P15 to program a shield, and nothing is connected to P22, then P15 will be the default. I'm not sure how to change the default, but I'll look into that for you. Why would you need to have both connected at the same time though? 

Best regards,

Heidi

[Smart.Enrg]

Thanks Heidi,

1) Will check (external target supply connected to P15 pin#3/ VTG) and confirm if works as expected

Heidi said:

Why would you need to have both connected at the same time though?

Sorry for any confusion I was quoting from what I read in that URL in my original message. I'm in fact looking to use only one programming connector (P15 or P22) Not both at the same time. In fact previously I confirmed P22 works well.

Best,
SE

[Heidi]

I see. So if you only have one of them connected that's gonna be the default, so you don't have to change it.