We currently have a solution that uses inboard DFU for firmware updates. While ODFU is also supported (for bootloader changes/partition resizes), we generally prefer IDFU because of the possibility of user feedback. However, it’s quite slow, taking around 30 minutes or more to transfer a 1.1 MB binary from Notecard to the host once it’s downloaded. Each request to notecard to retrieve 4KB of binary data takes about 7 seconds running over aux.serial at 115200 baud. (back of envelope math: 1100000 / 4096 = 269 chunks * 7s = 31 minutes.)
Is it possible to use the card.binary buffer with inboard DFU? I imagine this would reduce the transfer time considerably and allow larger chunks of the binary to be received by the host.