Screen programming could be faster if different colors are used, something akin to FSK as opposed to OOK...
The 38kHz 2400 baud IR bootloader I'm working on is almost going.
But I've just discovered the IR demodulators I'm using are not rated for continuous operation.
After a few bits in a row, exceeding a certain duty cycle, the demodulator stops responding.
I have some TSOP58038 parts on order, rated for continuous, that should fix this.
With 2400 baud and ten bits per byte (8 + start and stop) we get 16 carrier waves (@ 38Khz) in a single bit.
The carrier wavelength being 26.3us and the the baud bit length being 426us.
There is some phase shift (about 8 wavelengths) as a result of the demodulation circuit that prevents it from being any faster.
Interestingly, IRDA specifies the carrier to be 3/16 the wavelength of the bit length.
So the carrier for 115k baud is 614 kHz, and the carrier for 9600 baud is 51kHz.
This is considerably better than the 1/16th I'm getting with the 38kHz TV remote demods..
I've also looked at the audio bootloader.
It's going to have the same speed issue as 38kHz IR, a little slower, the maximum carrier will be 20kHz.
At least with audio, multiple carries can be used for a multi-bit FSK scheme.
But that would require either decoding FSK in the AVR or some external analog filters...