[nRF52840dk] nrfjprog always reading external flash least significant bit as 0

[Brad Campbell]

I'm trying to use nrfjprog to read and write the mx25r6435f external flash on the nRF52840dk board (I have version 3.0.0). However, what I am noticing is that nrfjprog always reads the least significant bit of every byte as 0. For example:

$ nrfjprog --erasepage 0x12000000-0x12000004
WARNING: An address for the --erasepage operation is not aligned to the start
WARNING: of page.
Initializing the QSPI peripheral.
Erasing range [0x00000000 - 0x00000FFF] in the external memory device.
Uninitializing the QSPI peripheral.

and then immediately after:

nrfjprog --memrd 0x12000000 --log
[ #####                ]   0.000s | Reading external memory, 0x0004 bytes @ 0x00000000 - 0x00
[                      ]   0.000s | Reading external memory, 0x0004 bytes @ 0x00000000 - 0x00
[ #################### ]   0.000s | Reading external memory, 0x0004 bytes @ 0x00000000 - Done
0x12000000: EEEEEEEE

The read always returns with each byte having a 0 as the least significant bit. This also happens when I try to program the external flash. The erase works successfully, the write works successfully, but the verify (read) "fails" because nrfjprog thinks the LSB is 0.

I've run code on the nrf that reads the flash and it reads correctly (after erase it is all 0xff and after programming with nrfjprog I get the expected values.

My programming:

cat a.bin
hello from tock flash

arm-none-eabi-objcopy -v -I binary -O ihex --change-addresses 0x12000000  a.bin a.hex
nrfjprog --qspichiperase --program a.hex

Is this a known issue? What can I do?

Debugging

I've tried every version of nrfjprog back to 10.12.1. Through 10.13 I see the same issue. At 10.12.1 it seems I can no longer read the flash, probably because I have a newer version of the nRF52840-dk.

My Setup

I'm on MacOS Ventura (13.3.1a).

[Brad Campbell]

I found an older nRF52840dk to try on mac.

$ nrfjprog --version
nrfjprog version: 10.17.3 external
JLinkARM.dll version: 7.86h

nRF52840dk v1.1.0 (2019.12):

$ nrfjprog --qspieraseall
WARNING: An operation that can take up to several minutes is being executed.
WARNING: Please remain patient.
Initializing the QSPI peripheral.
Erasing.
Uninitializing the QSPI peripheral.
$ nrfjprog --memrd 0x12000000 --log
0x12000000: FFFFFFFF                              |....|

nRF52840dk v3.0.0 (2022.36):

$ nrfjprog --qspieraseall
WARNING: An operation that can take up to several minutes is being executed.
WARNING: Please remain patient.
Initializing the QSPI peripheral.
Erasing.
Uninitializing the QSPI peripheral.
$ nrfjprog --memrd 0x12000000 --log
0x12000000: EEEEEEEE                              |....|

So, on my machine at least, even with nrfjprog 10.17.3, there is something different about the newer nRF52840dk in how it reads the external flash.