ATSam4S can it really not do DMA to timers?

1 post / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi,

 

I have no experience with hardware side of things in the ATSAM devices and am doing some reading before I dive in.

 

I have a project that I would like to be able to create a pulse train with a varying period of 4 to 10 clock cycles. (A clock cycle being 30ish Mhz while the CPU could run up to 120Mhz)

 

This sequence is 600+ periods long and then will repeat for 200+ sequences.

 

During that time the next sequence of 200+ periods can be calculated and put into RAM.

 

The start of the sequence has to be a fixed period after an incoming pulse.

 

My thought was to use an input capture to get the incoming pulse.  Add the start delay to this and write that out as an output compare.  Then have the DMA feed a sequence OCs for the 300 periods.

 

However my reading seems to indicate that the SAM S series can not use the timer as a DMA trigger.  Only the SAM D/R/L can.

 

Is this true.  Can you not actually use DMA to be triggered off or feed the timer units?

 

I think I might be able to hack around my requirements with either an SPI, the SSC or the PWM module and some fancy ASM code to count clock cycles for the start time.  But it would be so much easier if the start tick could be done automatically from an IC and OC.

 

tnx,