I have a custom nrf52 chip on a pcb with swd pins exposed. I have cloned and installed the latest openocd from https://github.com/ntfreak/openocd. The latest version includes all the latest pathes for the nrf52 chip, so no need for any additional changes as suggested in many older guides online. I am able to connect to the chip using ST-LinkV2. when connected I can read and write memory locations using mdw and mdb. I can also run some basic openocd commands like dump_image e.t.c, which confirms that the setup is good. But halt and program commannds always lead to errors like:
JTAG failure -4
JTAG failure -4
JTAG failure -4
JTAG failure -4
JTAG failure -4
JTAG failure -4
target halted due to debug-request, current mode: Thread
xPSR: 00000000 pc: 00000000 msp: 00000000
jtag status contains invalid mode value - communication failure
Polling target nrf52.cpu failed, trying to reexamine
Examination failed, GDB will be halted. Polling again in 100ms
Previous state query failed, trying to reconnect
jtag status contains invalid mode value - communication failure
Polling target nrf52.cpu failed, trying to reexamine
if I try to use flash image_write I get the error,
JTAG failure
Error setting register
error starting target flash write algorithm
Failed to enable read-only operation
Failed to write to nrf52 flash
error writing to flash at address 0x00000000 at offset 0x00000000
in procedure 'dap'
jtag status contains invalid mode value - communication failure
Polling target nrf52.cpu failed, trying to reexamine
I have read different guides online, and one of the possible solutions involves the APPPROTECT register which has to be disabled to enable any writes to flash. APP_PROTECT, But the dap commmand which is supposed to help us access this bit,
dap apreg 1 0x04 0x01
returns an error:
invalid subcommand apreg 1 0x04 0x01
Please, I will like to know if anyone has had success programming a new empty nrf52 chip with the stlink-v2 and the steps which are necessary, or if any one has encountered similar problems. Thanks.
Here is my config file:
#nRF52832 Target
source [find interface/stlink.cfg]
transport select hla_swd
source [find target/nrf52.cfg]
#reset_config srst_nogate connect_assert_srst
If anyone encounters this problem, I solved the problem by getting an original Jlink-Edu. I also had to pull the reset pin of the microcontroller high to get the jlink working.