Just how many timers does the SAM3U have, anyway?

Discussion around product based on ARM Cortex M3 core.

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Andy Peters
Posts: 46
Joined: Mon Jul 08, 2013 11:09 pm

Just how many timers does the SAM3U have, anyway?

Thu Jul 03, 2014 12:06 am

So the very first line of Section 36.1 of the SAM3U-series complete user guide, we're told that "The Timer Counter (TC) includes 9 identical 16-bit Timer Counter channels." The number-of-channels assertion is repeated as the first bullet point of Section 36.2.

Yet the rest of the documentation seems to discuss only three Timer Counter channels, not nine. Either I am smoking crack, or Atmel has redefined "9" to mean "3," or there are really just three Timer Counter channels. 

What's the real deal?
Tyler@Technica
Posts: 8
Joined: Thu Jul 03, 2014 12:02 am

Re: Just how many timers does the SAM3U have, anyway?

Thu Jul 03, 2014 6:07 pm

I'm not sure how different the SAM3U is from the SAM3X, but I do believe I can shed some light on this.  I ran into the same thing with the SAM3X documentation.

As far as I understand it, you have TC0, TC1, and TC2. and then within each of those you have three categories, and within each of those you have three separate signals.

The breakdown seems to be as follows - 

TC0
   TCLK0 , 1, and 2
   TIOA0, 1, and 2
   TIOB0, 1, and 2

TC1
   TCLK3 , 4, and 5
   TIOA3, 4, and 5
   TIOB3, 4, and 5

TC2
   TCLK6 , 7, and 8
   TIOA6, 7, and 8
   TIOB6, 7, and 8

At some point Atmel seems to rename the TIOA channels (9 total) as TC0 - TC8, which of course causes a lot of confusion.  However, each one of those 9 channels can be configured as a TC capture or TC waveform, so as far as I can tell there are 9 individual TC channels.  

My problem is that I need access to one of the TIOB channels, but can't seem to figure it out.

Anyway, hope this helps!
Andy Peters
Posts: 46
Joined: Mon Jul 08, 2013 11:09 pm

Re: Just how many timers does the SAM3U have, anyway?

Thu Jul 03, 2014 7:06 pm

Hah, that is completely baffling! I've opened a support ticket with Atmel, perhaps I'll get some clarity, which I'll post here.
Andy Peters
Posts: 46
Joined: Mon Jul 08, 2013 11:09 pm

Re: Just how many timers does the SAM3U have, anyway?

Mon Jul 07, 2014 6:37 pm

Andy Peters wrote:Hah, that is completely baffling! I've opened a support ticket with Atmel, perhaps I'll get some clarity, which I'll post here.
clarity: Atmel says it's an error in the docs and there are only three timers. Docs will be fixed.
Tyler@Technica
Posts: 8
Joined: Thu Jul 03, 2014 12:02 am

Re: Just how many timers does the SAM3U have, anyway?

Tue Jul 08, 2014 3:14 pm

Andy Peters wrote: clarity: Atmel says it's an error in the docs and there are only three timers. Docs will be fixed.
Interesting.  That doesn't really seem right to me, unless I just don't understand the actual architecture of the TC peripheral (which is likely).  Like I said, I've had more than three TC "channels" up and running at once.  But maybe by three timers they simply mean three timer modules that each have multiple, individually programmable "channels".  Dunno.

Thanks for the update though!  What form did you use to open the ticket with them?  Might come in handy in the future.
Andy Peters
Posts: 46
Joined: Mon Jul 08, 2013 11:09 pm

Re: Just how many timers does the SAM3U have, anyway?

Tue Jul 08, 2014 11:29 pm

Tyler@Technica wrote:Thanks for the update though!  What form did you use to open the ticket with them?  Might come in handy in the future.
Start here: http://support.atmel.com/bin/customer.exe

Create an account if you don't already have one (it's separate from this forum account). Then choose "submit new request." Fill out the form. They replied within a day.

-a
Andy Peters
Posts: 46
Joined: Mon Jul 08, 2013 11:09 pm

Re: Just how many timers does the SAM3U have, anyway?

Sat Jul 19, 2014 1:08 am

Tyler@Technica wrote:I'm not sure how different the SAM3U is from the SAM3X, but I do believe I can shed some light on this.  I ran into the same thing with the SAM3X documentation.

As far as I understand it, you have TC0, TC1, and TC2. and then within each of those you have three categories, and within each of those you have three separate signals.
SAM3U has only one Timer Counter block, TC0, which consists of three timers and their configuration. The SAM3X has three TC blocks, TC0, TC1 and TC2, each of which have three timers.

So that's the confusion there, and my guess is that the SAM3U documentation was cut-and-pasted from the SAM3A/X docs.

Of course it gets worse, in that the header files supplied with ASF for all of the SAM3U devices have entries for TC1 and TC2 interrupts and register base addresses. Arrgh.

-a
wasif
Posts: 2
Joined: Fri Oct 03, 2014 3:47 pm

Re: Just how many timers does the SAM3U have, anyway?

Wed Oct 15, 2014 6:34 pm

i have also had the same confusion and the datasheets have messed up information, but i found out that mostly 100 pin devices have 6 16-bit timers/counters in sam3s series and 64 pins deivces have 3 16-bit timers/counter regardless of whatever the datasheet says 
eng.mmostafa80
Posts: 29
Joined: Sat Nov 26, 2011 10:20 am

Re: Just how many timers does the SAM3U have, anyway?

Thu Oct 16, 2014 10:22 am

I contacted Atmel for this point.
They confirmed that the datasheet is wrong.
SAM3U has only 3 fully independent timers.
Andy Peters
Posts: 46
Joined: Mon Jul 08, 2013 11:09 pm

Re: Just how many timers does the SAM3U have, anyway?

Sat Oct 18, 2014 1:58 am

wasif wrote:i have also had the same confusion and the datasheets have messed up information, but i found out that mostly 100 pin devices have 6 16-bit timers/counters in sam3s series and 64 pins deivces have 3 16-bit timers/counter regardless of whatever the datasheet says 
SAM3U has one TC and that TC has three independent timer/counters.

But -- when that single TC block is configured as a quadrature decoder, all three of the timers in the block are reserved for that function. So if you care only about speed and you don't use the index, you might think that timer 1 is available for other use but it is not.

The quadrature decoder doesn't work, anyway, so that's a moot point.

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