DMA and GPIO speed ?

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on May 22, 2017 by Kaiyue WANG
Content originally posted in LPCWare by Pacman on Sat Nov 09 11:57:31 MST 2013
I've tried using the DMA to output data on the GPIO.

Unfortunately, it seems I can only get it to change pin state 24000000 times per second.
I've tried synchronizing to Timer0 at 204MHz, but if I set Match Register 0 to less than 18, the frequency does not increase.

If I disable synchronizing, I can reach 24M by using AHB Master 1 for destination and AHB Master 0 for source.

But I can't seem to get it faster than that. (And I can't seem to do memory-to-memory transfers on GPIO pins with AHB Master 0)

The LPC1768 can go much higher, probably because you don't have to choose an AHB Master.

Has anyone gone beyond that 24M outputs per second using the DMA ?