Programming nRF52832 always sets readback

[Knud]

I’ve been developing the FW for an nRF52832-based module that controls a simple lighting product.

The capabilities include support for secure DFU and a modified version of the Nordic BLE UART example for communicating with and configuring the light bar.

I’ve been using SDK 16 and the makefile environment along with nrf tools. To debug, I’ve been using a Segger JLink Plus and RTT. I’ve been developing using this setup with previous SDKs for about 3 years now, so kind of know my way around.

All that has been going very well. Making the bootloader was not too bad and works reliably. The main application compile, flash, debug cycle using nrfjprog —-program xxx.hex —-sectorerase following by connecting with JLinkExe always worked.

However, earlier today, I started to see errors involving readback protection. And now it’s to the point where everytime I have to wipe the chip, put back the bootloader, and then program it. If I then try to use JLinkExe, as soon as I connect it says “CTRL-AP indicates that the device is secured.” and then its automatically erased.

I am pretty sure that I am not mucking with APPROTECT or anything in UCIR, so am mystified.

What I am afraid of is that after many flashings of the chip I have a FLASH problem.

Any thoughts from you experts?

Thanks,

steven

[Einar Thorsrud]

Hi Steven,

The only explanation I can think of is if the hex you are programming contains data in the APPROTECT register in UICR. Did you build the bootloader with NRF_BL_DEBUG_PORT_DISABLE set to 1 in sdk_config.h?

Einar

[Knud]

Thanks. Was pointed in the same direction by a Nordic support engineer and indeed that was the problem.

My dilemma now is why was it ever working? I looked at when I modified the `sdk_config.h` and created the first bootloader image, and it was back on Dec 20. I've been using that for testing ever since and never had the readback block. 

Probably not worth fussing over as clearly the NRF_BL_DEBUG_PORT_DISABLE setting needed to be done (0).

I'd like to humbly suggest that a discussion of this setting be added to the Getting Started guide.