NRF51 SWD flashing

[VoidGreen]

Hi everyone,

I implemented nrf51 flashing through SWD (external MCU is used). After first flashing and reset when we enter debug mode on SWD second time we have a busy state (NVMC_READY (0x4001E000 + 0x400) is set to zero) from NVMC. What could be the reason?

PS: if we power down NRF51 we can flash it once again, but only once.

[Stian Røed Hafskjold]

So what are you using to flash the chip? And which software? I've never seen that with a JLink. You could try to do a pin reset after flashing, set the 0x40000544 register to 1, and then hold SWDIO and SWDCLK low for a minimum of 100µs.

[VoidGreen]

I found the reason for that bug. |It looks like if WF uses NVMC and it conflicts with SWD flashing through NVMC. So another question is how to stop and maybe reset execution of FW code through SWD?

[Stian Røed Hafskjold]

Again, what hardware/software are you using? Are you developing your own debugger? Then you should check out ARM documentation. infocenter.arm.com/.../index.jsp, infocenter.arm.com/.../index.html. And this whitepaper on production programming: infocenter.nordicsemi.com/.../intro.html. You need to access the DAP to halt the processor.

To reset the chip you can write 0x05FA0004 to address 0xE000ED0C