[NRF81522] Can't enable Read Protection ALL (RBPCONF)

[JFGagnon]

Hello,

I am trying to enable the read protection on the NRF51822 on a custom board. By looking through the forums, I found different ways to try and enable the read protection.

According to the reference manual, bits 8 to 15 from RBPCONF must be set to 1 in order to enable the read protection for all the chip. RBPCONF is a RW register, so we should be able to write to the register directly.

So using sd_flash_write, I have this function.

void UTILS_EnableReadProtection (void)
{
#ifdef RELEASE
uint32_t RegisterValue;

RegisterValue = ~(0x0000FF00);
// Check if read-back mechanism is turned ON.
if((uint32_t)((NRF_UICR->RBPCONF & UICR_RBPCONF_PALL_Msk) >> UICR_RBPCONF_PALL_Pos) != UICR_RBPCONF_PALL_Enabled) {
sd_flash_write((uint32_t *)&NRF_UICR->RBPCONF, &RegisterValue,1);
}
//nrf_nvmc_write_word(0x10001004, 0x0000FF00);
#endif
}

I tried both the method with sd_flash_write, or with nrf_nvmc_write_word to no avail. I tried with and without power cycle and still the same.

What am i missing here?

Thanks,

Jean-Francois

[Jørgen Holmefjord]

Hi,

I tested this out, and using nrf_nvmc_write_word(0x10001004, 0x0000FF00); worked on my board (nRF51 DK/PCA10028). Note that the sd_flash_write will report an error if the destination is outside of the flash area, this function cannot be used for writing to UICR. You must write this register before enabling the softdevice, or disable the softdevice before doing the write.

To be exact, I added this code and called the function from start of main():

#define RELEASE

void UTILS_EnableReadProtection (void)
{
#ifdef RELEASE
// Check if read-back mechanism is turned ON.
if((uint32_t)((NRF_UICR->RBPCONF & UICR_RBPCONF_PALL_Msk) >> UICR_RBPCONF_PALL_Pos) != UICR_RBPCONF_PALL_Enabled) {
	nrf_nvmc_write_word(0x10001004, 0xFFFF0000);
}
#endif
}

Best regards,
Jørgen

[Jørgen Holmefjord]

Setting RBPCONF will not prevent you from using the SWD interface, it will only prevent you from reading back content in flash. I used nrfjprog from verification:

$ nrfjprog --recover
Recovering device. This operation might take 30s.
Erasing user code and UICR flash areas.

$ nrfjprog --memrd 0x10001004
0x10001004: FFFFFFFF                              |....|

## Flash FW here

$ nrfjprog --memrd 0x10001004
0x10001004: FFFF00FF                              |....|

$ nrfjprog --memrd 0x1000
ERROR: The operation attempted is unavailable due to readback protection in
ERROR: your device. Please use --recover to unlock the device.

I set both for testing purposes, as you can see above, PALL is sufficient to enable readback protection for full chip. PR0 can be used to protect only the region from 0x0 to the number of pages set in UICR->CLENR0 register.

[Jørgen Holmefjord]

What is the error you get without the --log option?

Do the board work with other computers? Are you using a nRF51 DK, or some custom board?

[JFGagnon]

The error I am getting is this :

PS C:\Users\Gagnonje> nrfjprog --memrd 0x100010004 --log
ERROR: JLinkARM DLL reported an error. Try again. If error condition
ERROR: persists, run the same command again with argument --log, contact Nordic
ERROR: Semiconductor and provide the generated log.log file to them.

The log file I posted above is the result of --log.

This is a custom board with a     NRF51822. I can use all of the Segger tools on the custom board, but nrfjprog doesn't work. 

I can JTAG in the board just fine on different computers and we've done the whole dev with the segger tools.

I did not try nrfjprog on another computer.

edit : Running powershell in admin doesn't make a difference, still the same errors

[Jørgen Holmefjord]

The -1 error typically means that the J-Link cannot find the chip, which can be caused by wrong supply voltage, wrong connections, board not powered, etc. What J-Link device are you using with the custom board, and how is it connected? Strange if you are able to use other tools with the same setup.

[JFGagnon]

I use the Flasher Arm from Segger which we bought at the beginning of this year (February I think). If I don't touch the setup, I can JTAG the chip repeatedly but can't use any nrfjprog commands. 

We've run the panelizeds board through multiple rounds of testing with a successful programming using the J-Link lite as well, so I am confident that the voltage levels, as well as the connections are correct.

Just for testing, I flashed the softdevice (which worked) and tried to use nrfjprog --recover right after, without touching the setup, and I still get the same error as above. 

[Jørgen Holmefjord]

I tried upgrading to the same version of nRF Command Line Tools that you are using, but I'm not able to reproduce this behavior with a DK. Can you check if you are able to use nrfjprog with a different computer, to determine if this is caused by software or hardware problems?