High Speed Timer on the AVR - Page 1
Forum section: electronics / general

author: aep9690
author_rank: Regular Contributor
timestamp: March 31, 2015, 02:01:47 am
content: I need a microcontroller with high speed timers (>200MHz). At work we try to standardize on a family to make things easier on the software team so it would be great if it was an Atmel. From what I can tell the Atmel microcontrollers can't run their timers any faster than its CPU speed.Page 1259:http://www.atmel.com/Images/Atmel-11297-32-bit-Cortex-M7-Microcontroller-SAM-V70Q-SAM-V70N-SAM-V70J_Datasheet.pdfI really hate long datasheetsThere are inputs for external clocks to be used with the timers but I can't find a spec on the maximum speed. On other devices with high speed timers that I have found it is usually pretty clear. Ex: 4.7ns for MSP430F51x2, 217ps for STM32F334 etc. Can someone clear this up for me?

author: dannyf
author_rank: Super Contributor
timestamp: March 31, 2015, 11:03:13 am
content: QuoteTry to avoid microcontroller then - they all have long datasheets.

author: Psi
author_rank: Super Contributor
timestamp: March 31, 2015, 11:06:14 am
content: i seem to remember that there is a few AVR with a 64mhz timer clock, well above the cpu clock.ATTiny45 is one

author: dannyf
author_rank: Super Contributor
timestamp: March 31, 2015, 11:18:02 am
content: QuoteThe datasheets do specify that those counters are synchronous, and provide a factor that link the counter's max speed with that of the main clock.

author: aep9690
author_rank: Regular Contributor
timestamp: March 31, 2015, 06:01:36 pm
content: Okay, that's what I was afraid of. Thanks for clearing that up.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 31, 2015, 07:40:18 pm
content: I've been reading on the XMEGA series, unfortunately they aren't terribly concise in their information (in their defense, the XMEGAs have much more hardware than the old MEGAs). The internal PLL claims 128MHz maximum output, but it isn't clear where this can be used (the AVR core itself seems to only be rated for 32MHz, when sufficient VDD is available). The timers also claim "extended resolution", but it isn't clear to me yet if this is automatically generated, or just more bits (and therefore only useful when the PLL is clocking them extra), or what.There are devices out there which have internal delay or phase shift circuitry, which allows continuously variable (so to speak; i.e., limited by the internal DAC driving it) "fine" control, or at least additional (sub-clock) steps, for PWM or frequency or both. Those would be excellent for self contained control applications (motor control, or yes, even straight up switching supplies -- given suitably clean code, of course!).Tim

author: aep9690
author_rank: Regular Contributor
timestamp: April 01, 2015, 05:57:41 am
content: Quote from: dannyf on March 31, 2015, 11:03:13 amCorrection. I hate datasheets that are 1700 pages long and contain very little of the electrical specifications I care about.

author: Psi
author_rank: Super Contributor
timestamp: April 01, 2015, 07:36:46 am
content: There are some MCU's with small onboard FPGA/CPLDYou might be able to use the FPGA part for your highspeed stuff.But expect to pay a premium for it.External timing hardware maybe the best option.

author: dannyf
author_rank: Super Contributor
timestamp: April 01, 2015, 10:43:12 am
content: QuoteEasy: write your own datasheet so the electrical specificatin can be as long or short as you want. Problem solved.

author: aep9690
author_rank: Regular Contributor
timestamp: April 01, 2015, 06:19:31 pm
content: Quote from: dannyf on April 01, 2015, 10:43:12 amNo