Can't program board when audio cable plugged into board

[cory123]

I am developing a custom board with NRF52832 and an audio DAC which outputs to a headphone jack. When the headphones are plugged in I can't program the board with my Segger programmer. I can connect and start the debugger without programming the chip. I think the headphones are interfering with the ground plane somehow. Here is the screenshot of Embedded Studio when I try to program the board. Does anyone know why this is happening?

[Håkon Alseth]

Hi,

 

It sounds like the connector is shorted or somehow interferes with the rest of the board.

Have you tried measuring current consumption, seeing if there's any shorts on the board?

Does this happen to more than one custom board?

 

Kind regards,

Håkon

[cory123]

I'm pretty sure I had the same problem with an identical board. When you say the connector is shorted, are you referring to the programmer connection? I'm using a tagconnect cable which may not be making a great connection. But when I unplug the headphones I can program without any problem.

When I plug in an I2C device via a header and  4cm wire I get the same problem independent of the headphone issue. It seems like the cables I'm plugging in are somehow messing with the stability of VCC and GND. I will probe with my multi-meter and report back. Thanks!

[Håkon Alseth]

Hi,

 

cory123 said:

When I plug in an I2C device via a header and  4cm wire I get the same problem independent of the headphone issue. It seems like the cables I'm plugging in are somehow messing with the stability of VCC and GND. I will probe with my multi-meter and report back. Thanks!

Does your firmware handle this scenario? If the firmware asserts, the default behavior is to do a soft-reset, and if it also asserts (ie. resets) in the boot-up process; you can get into a scenario where it is hard to attach to the nRF. Try enabling blocking asserts via adding the preprocessor symbol "DEBUG".

 

Kind regards,

Håkon