NRF52 enters DebugMonitor mode by itself when changing RTC frequency

RE: NRF52 enters DebugMonitor mode by itself when changing RTC frequency

Vidar Berg — Wed, 13 Feb 2019 07:27:11 GMT

Thanks for the update. This appears to be a bug in Jlink commander. The 0x0B number is reserved for the SVcall IRQ on all ICs based on the Cortex M4. Documentation of the IPSR register can be found in the generic user guide from ARM (link), and the ISR numbers specific to nRF52 can be found in the nrf52.h/nrf528xx.h header.

RE: NRF52 enters DebugMonitor mode by itself when changing RTC frequency

Andy — Tue, 12 Feb 2019 14:12:05 GMT

By the way, how do you know that 0x0B is SVCall IRQ and debug monitor is 0x0C? JLink was showing 00B (DebugMonitor) in the halt output. Where can I find that documentation?

RE: NRF52 enters DebugMonitor mode by itself when changing RTC frequency

Andy — Tue, 12 Feb 2019 14:10:57 GMT

I found the issue. It was that I was calling that function before the BLE stack initialization, and since the RTC requires the SoftDevice to be enabled in order to use the LF clock, it wasn't working.

RE: NRF52 enters DebugMonitor mode by itself when changing RTC frequency

Vidar Berg — Tue, 12 Feb 2019 12:33:54 GMT

Hi,

0x0B is the SVCall IRQ, debug mon is 0xC. Does your program still get stuck in this interrupt, and does your program get past ble_stack_init()?