Ok, here’s the deets on setting the SSID. The SSID is made of two parts - a prefix and the device serial.
Setting the SSID Prefix
The SSID prefix can be set by writing the prefix value to the device.
First, create a file that contains the length of the prefix, followed by the prefix itself. In bash, this is done like this:
echo -e -n "\x03Rad" > ssid_prefix
The \x03 writes a literal value 3 (not the ASCII character ‘3’) to the file - 3 being the length of our prefix “Rad”. The value is specified on the command line as hex, so values over 10 start ‘A’, ‘B’ etc… The maximum allowed length of the prefix is 24.
(There’s no need to add a trailing ‘-’ to the prefix, the device automatically adds a ‘-’ between the prefix and the 6-digit serial.)
Then flash this to the device like this:
dfu-util -d 2b04:d006 -a 1 -s 1826 -D ssid_prefix
Next time the device enters softAP mode it will use the given prefix.
Setting the Device Serial
The Device Serial can be set by writing the 6-digit serial to the device.
First, create a file that contains the 6-digit device serial. In bash, this is done like this:
echo -n "ABCDEF" > serial
Then flash the serial to the device:
dfu-util -d 2b04:d006 -a 1 -s 1852:6 -D serial
Next time the device enters softAP mode, it will use the given serial.