nRF5 DFU over serial

RE: nRF5 DFU over serial

Hung Bui — Mon, 04 May 2020 13:44:13 GMT

I'm glad that you figured out most of the stuff. Let me know if you still have any issue transferring the image.

RE: nRF5 DFU over serial

Phil — Thu, 30 Apr 2020 22:50:08 GMT

Yes, thanks. I had found that after looking through the boot-loader. Your code sets the data object length of the last object to the length of the remaining firmware image bytes. It also looks like the code in the boot-loader requires the last data object length to be equal to the length of the remaining bytes. I might be wrong here. However, the issue is that I was requesting a data object size less than 4096 bytes that was not the last data object. The SDK15.3.0 DFU documentation is not clear on this.

My problem is that the firmware size is in the init packet, which sent to the boot-loader successfully. However, I was down-loading a test image while developing my DFU protocol code. This is writing a generated test pattern into the nRF52 ROM and the total length was much less than the firmware image length.

By the way, we are implementing the DFU controller as a state machine. We process the response to every command sent to the boot-loader. We set the PRN to 1 at the start to get a response to every write data packet. That way the DFU is self-timing and the offset returned in the response to write commands keeps track of the progress. Also there is no need to request a CRC just before the execute command as this is returned in the write data response.

Thanks for your help. Much appreciated.

RE: nRF5 DFU over serial

Hung Bui — Thu, 30 Apr 2020 14:24:41 GMT

Hi Phil,

The firmware I made was quite a long time ago so I don't remember all the detail.

But the way it works in our bootloader is that you only set the data object size once, for all packets. And the last packet is the only exception. You don't need to set the data object size for the last packet. The bootloader detect that automatically because the size of the image is sent at the beginning already.

If you have a look at the on_data_obj_create_request() function in nrf_dfu_req_handler.c you can find an error log "NRF_LOG_ERROR("Object size must be page aligned");" Data object size need to be page aligned, so either 4096 or 8192 and so on.

RE: nRF5 DFU over serial

Phil — Wed, 29 Apr 2020 23:34:05 GMT

I've narrowed my problem down to a specific issue. I cannot send a Create data object command with size other than 0x1000 (4096). This size is the max_size returned by the SELECT data object request.

Create data object: size = 512: [01 02 00 02 00 00]. Response [60 01 03]: status = missing or invalid parameter

Create data object: size = 4096: [01 02 00 10 00 00]. Response [60 01 01]: status = success

I notice in your example code that you send a Create data object command at the start of each data object transfer. Each one, except the last, has size=4096. The size of the last one is the length of the remaining bytes of the firmware image. This is exactly what we intend to do. I also notice you are never checking the response to the Create data object command (or any commands). Does this actually work?

Does the number of bytes transferred for each data object have to equal the size in the Create data object command? Could we just always create a data object of max_size and just send fewer bytes where necessary before sending the EXECUTE command?

RE: nRF5 DFU over serial

Phil — Wed, 29 Apr 2020 12:34:33 GMT

Thanks Hung. We do all the steps in your guide.

I had a look at your DFUMaster_UART code. The DFU message sequence diagram in SDK15.3.0 says to send a SELECT command [06 01] to select the Init object before the transfer of the Init packet. Then also send a SELECT command [06 02] to select a data object before transferring the firmware image.

I can't see where you send any SELECT command in your code. Does that mean it is not strictly necessary?

Also I notice you send the EXECUTE command at the end of each data object during the firmware image transfer. That answers one of my questions.

RE: nRF5 DFU over serial

Hung Bui — Wed, 29 Apr 2020 10:09:44 GMT

Hi Phil,

I actually made an example of DFU controller running on nRF52 that you can have a look: https://devzone.nordicsemi.com/nordic/short-range-guides/b/software-development-kit/posts/getting-started-with-nordics-secure-dfu-bootloader#h108sjziaxo3m81rkgr1has5r1d72qtu

I would suggest to test the example and review the code. If you still have any question, please let me know.

RE: nRF5 DFU over serial

Phil — Wed, 29 Apr 2020 06:37:29 GMT

Furthermore after some trial and error, I found I couldn't send a CREATE data object command with a size less than the max_size returned by the SELECT data object command.

For example SELECT data object returns max_size 0x1000 (4096)

If the firmware image size is 0x3200, this requires 3 data objects of 0x1000 and 1 data object of 0x200

When command CREATE data object of size 0x1000, [01 02 00 10 00 00] is sent the response is [01] success. After that the data object is sent Ok and the EXECUTE command also returns success.

When sending the last 512 bytes the command CREATE data object of size 0x0200, [01 02 00 02 00 00] , returns status code [03] NRF_DFU_RES_CODE_INVALID_PARAMETER.. Then it doesn't accept any write commands.

It seems the only size that is valid for the Create Data Object command is the max_size returned by the Select data object request.

How do we send the last data block of 512 bytes in this example?