А что мешает вставить "окна" в массиве с другим адресом CS ?
Код
The Variable Peripheral Selection allows buffer transfers with multiple peripherals without reprogramming
the Mode Register. Data written in SPI_TDR is 32 bits wide and defines the real data
to be transmitted and the peripheral it is destined to. Using the PDC in this mode requires 32-bit
wide buffers, with the data in the LSBs and the PCS and LASTXFER fields in the MSBs, however
the SPI still controls the number of bits (8 to16) to be transferred through MISO and MOSI
lines with the chip select configuration registers. This is not the optimal means in term of memory
size for the buffers, but it provides a very effective means to exchange data with several
peripherals without any intervention of the processor.
Пожертвовать памятью, но зато будет один запуск PDC
[ 2 байта для AD ] [ 2 байта окна для другого CS ] ... [ 2 байта окна для другого CS ] [ 2 байта AD ]
Буфер PDC должен быть 32битным