RE: Softdevice Update OTA

Ole Morten — Fri, 21 Mar 2014 16:36:24 GMT

Doing a softdevice update is as you say not trivial with the current softdevices. They do however not require that CLENR0 is set anymore, so you can in theory not set this, and then do erases as needed from a bootloader. ERASEALL would still erase the complete chip, but you could erase a softdevice page-by-page, while keeping the bootloader. However, if you lose power right after having erased page 0, before you have written a new softdevice, you will brick your device since this is where the vector table is. Future softdevice will include functionality to avoid the need to erase this page, so that such upgrade can be done safely.

Even so, updating a softdevice is a significant effort, that requires transferring significant amounts of data (> 80 kB), so I would be careful about making an application relying on doing this regularly.

Readback protection disables only readback, not writing. If you want to protect an area against writes, you'll have to use the PROTEN register in the MPU.

To have two applications on one chip, you'd currently have to implement interrupt forwarding in the application located right on top of the softdevice, to whichever application is currently running.

The accuracy of the TX power is specified to be +-4 dBm, both due to chip-to-chip variations and due to the tolerance in the matching network components. This should however not have a significant effect on performance. There isn't really any correlation between output power and bitrate, and with BLE, the bitrate is fixed at 1 Mbps anyway.

If you have follow-up questions, I'd be happy you post them separately, as separate questions when they have to do with different topics; having everything in one question tends to become very messy over time. :-)