does anyone know if it's possible to DMA a constant value using the STM32F103? I've scrutinized the datasheet but can't see anything obvious and nothing via Google either. Could do a single word in circular mode of course but it would be nice to avoid the bus access.
Yes this is possible. Just do not increment the source address in memory-to-memory or memory-to-peripheral mode.
DMA_CCRx->MINC (bit 7)