Hello everyone,
I hope someone will help me to solve the following strange problem.
I developed a perfectly working DSPBIOS 3.3 application, where frames of 16 bits data samples were regularly acquired from McASP/EDMA through the ping pong method: McAsp Rx section had external frame & clock.
Then I tried to modify such application, in order to acquire frames of 8 bits data with the same method:
8 bits samples are regularly acquired in the expected order, but at transfer startup, the receive buffer (ping) returned by the first EDMA IRQ callback is filled with three extra zero bytes, then its three pending bytes appear on the beginning of the second (pong) buffer, then the three pending pong bytes appear at the beginning of the ping buffer, and so on.
In no way extra zero bytes are transmitted at startup to the McAsp Rx port.
Maybe McAsp or EDMA configuration problem ?
Any insight on the problem is warmly welcome.
Thank you for your attention.