nRF52833 - OpenOCD ST-LINK MEM-AP Access Failure During Flashing

Subject: nRF52833 - OpenOCD ST-LINK MEM-AP Access Failure During Flashing

Hello Nordic Support Team,

I am working with an nRF52833 module and trying to flash firmware using OpenOCD 0.12.0 and an ST-LINK V2 debugger.

Environment:

  • Device: nRF52833

  • Debugger: ST-LINK V2 (V2J37S7)

  • OpenOCD Version: 0.12.0

  • Interface: SWD

  • Firmware: ble_app_blinky_pca10100_s140.hex

OpenOCD detects the ST-LINK successfully and reports:

SWD DPIDR 0x2ba01477

Target voltage is approximately 3.27 V.

However, during target examination and flashing, OpenOCD reports:

Error: [nrf52.cpu] Could not find MEM-AP to control the core
Error: [nrf52.cpu] Examination failed

Telnet diagnostics:

targets:
nrf52.cpu state: unknown

poll:
background polling: on
TAP: nrf52.cpu (enabled)

nrf52.cpu curstate:
unknown

dap info:
AP # 0x0

Troubleshooting performed:

  • Verified target power (~3.27 V)

  • Verified SWDIO and SWCLK wiring

  • Reduced adapter speed to 5 kHz and 100 kHz

  • Confirmed ST-LINK detection

  • Confirmed OpenOCD server startup

  • Connected through Telnet

  • Used nrf52.cfg target configuration

Thank you.

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