[Necromant] wrote a library to flash his microcontroller over an RF link using an NRF24L01 wireless communication module. The NRF24L01 is a cheap RF module that can be easily integrated into many microcontroller projects. Though there are Arduino libraries for driving the NRF24L01, [Necromat] decided to make a port of one with no Arduino dependencies.
The resulting bootloader fits into 4K of
RAM flash with packet loss and recovery along with user-configurable hardware or software SPI. Programming speeds are not the highest, but [ NecromatNecromant] believes this to be a property of the VUSB rather than the transfer rate from the NRF24L01 or the target microcontroller.
To program the target AVR chip, [
NecromatNecromant] used another NRF24L01 module connected to his uISP dongle over USB. Using a custom tool to interface with the uISP, the target board can be programmed in a similar fashion as avrdude. Check out the code for the ISP dongle and the AVR bootloader on his GitHub page.