TFTP DFU Block Size

[Amy]

I try to integrate the CoAP Server and TFTP DFU example code, and it works well.

[ENV]

• IoT SDK v0.9.0
• nRF52832 DK

According to the specification, the MTU of L2CAP is 1280 bytes.

The default APP_TFTP_BLOCK_SIZE in the TFTP DFU example code is 512 bytes.

When I try to increase it to 1024 bytes, it didn't work.

I try to look the LOG and find it works well before starting to receive the image file.

it will trigger STATE_RECV_COMPLETE state just after sending block 0 of 55 ACK instead of calling iot_tftp_resume() and receive next block of data.

the LOG shows below:

[TFTP]: Set value: /dfu/app/iot_app_dfu_prox.bin.
[TFTP]: Set value: octet.
[TFTP]: Set option: tsize with value: 0.
[TFTP]: Set option: timeout with value: 3.
[TFTP]: << iot_tftp_get
[TFTP]: << client_process
[TFTP]: >> client_process
[TFTP]: Received OACK.
[TFTP]: Negotiate options:
[FILE][PSTORAGE][C]VERIFY MODULE INITIALIZED()
[FILE][PSTORAGE][C]check module param
[FILE][PSTORAGE][C]check block id
[FILE][PSTORAGE][C]check module_param_cb
[TFTP]:    TSIZE:   57012
[TFTP]:    TIMEOUT: 3
[TFTP]:    BLKSIZE: 1024
[TFTP]: Create ACK packet.
[TFTP]: Send packet.
[TFTP]: Send packet to UDP module.
[TFTP]:     Recv code: 00000000.
[TFTP]: << client_process
[TFTP]: >> client_process
[TFTP]: Received DATA.
[TFTP]: Received next DATA (n+1).
[TFTP]: Create ACK packet.
[TFTP]: Send block    0 of 55 ACK.
[TFTP]: << client_process
[TFTP]: >> iot_tftp_resume
[TFTP]: Send packet.
[TFTP]: Send packet to UDP module.
[TFTP]:     Recv code: 00000000.
[TFTP]: Complete due to STATE_RECV_COMPLETE state.
[TFTP]: Raise TRANSFER COMPLETE event.
[TFTP]: Reset instance 0.
[APPL]: In TFTP Application Handler.
[APPL]: TFTP transfer complete - size 57012.
[APPL]: New firmware file successfully downloaded.
[IOT_DFU]: >> iot_dfu_firmware_validate
[IOT_DFU]: Application CRC mismatch.
[IOT_DFU]: CRC in device is 64028.
[IOT_DFU]: << iot_dfu_firmware_validate
[** ASSERT **]: Error 0x0000000B, Line 0, File

but decrease the APP_TFTP_BLOCK_SIZE works well.

I have no idea how to solve it, did I miss anything? what is the limitation of APP_TFTP_BLOCK_SIZE?

Sincerely, Thank you.

[Ole Bauck]

Can you try to change the max block size on the tftp server (see here)?:

cd /etc/default/
nano tftpd-hpa

in the option quotes add --blocksize 1024

save it and then restart tftpd 

/etc/init.d/tftpd-hpa restart

[Amy]

I have tried it but the situation is still the same !!!!!

[Ole Bauck]

The problem is actually with the memory manager. The largest blocksize is defined to be 1024 bytes, but the data with overhead can be up to 1280 bytes. You can add these two lines to sdk_config.c (preferably under MEMORY_MANAGER_LARGE_BLOCK_SIZE):

#define MEMORY_MANAGER_XLARGE_BLOCK_COUNT 2
#define MEMORY_MANAGER_XLARGE_BLOCK_SIZE 1280

[Amy]

Thanks for your recommendation, but it still not works.

The problem is still the same no matter I try to add MEMROY_MANAGER_XLARGE_BLOCK_COUNT and MEMORY_MANAGER_XLARGE_BLOCK_SIZE as you mentioned, or edit the MEMROY_MANAGER_LARGE_BLOCK_SIZE to larger number.

[Ole Bauck]

And it still works with APP_TFTP_BLOCK_SIZE set to 512 bytes? You have added the --blocksize option to the tftp server?

I took the tftp dfu example from the SDK, applied these three changes and it worked.