Why does softdevice update with DFU not work

[Andreas]

I have a working custom DFU bootloader based on the official bootloader from the SDK 8.1.0. Updating the normal application code works without any problem. Now I want to also update the softdevice (currently S120). Therefor I generated the update .zip file with the tool included in the MasterControlPanel version 3.9.0.6. I used the following command on the CMD:

nrf.exe dfu genpkg --softdevice s120_softdevice.hex --dev-type 0xffff --dev-revision 0xffff --sd-req 0xffff SD_DFU.zip

But when uploading this .zip file to the bootloader with the nRF Connect Android App, I can see that the bootloader breaks the communication after prevalidating the init package.

I can see that dfu_init_pkt_complete(); in dfu_transport_ble.c returns NRF_ERROR_INVALID_LENGTH. This comes from the dfu_init_prevalidate(...)function in dfu_init_template.c. The check:

if (((uint32_t)p_init_data + init_data_len) < 
        (uint32_t)&p_init_packet->softdevice[p_init_packet->softdevice_len])

goes wrong, and NRF_ERROR_INVALID_LENGTH is returned. Is it a problem on the bootloader side, or is it a problem with generating/transmitting the .zip file? Any help appreciated.

BR, BTprogrammer

[Andreas]

Hello Bjørn, thanks for your advice. Unfortunately this does not solve the problem. The expected legth seems not to match with the transmitted length...!? I tried it also with the official bootloader from SDK11. There is doesn`t work, also. So at the moment I think there is something wrong with generating the .zip file. Another assumption is that there is not enough flash space to store the new SD. But I am using the 256k nRF51 version. Does the bootloader automatically overwrite the aplication stored in flash? I expect that the new sofdevice is automatically stored above the already existing sofdevice. And if the transmission was successful, the old softdevice will be overwritten by the new one. Right?