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TM4C129XKCZAD: Gpios toggle speed.

CS Hsieh
Prodigy 260 points
Part Number: TM4C129XKCZAD

Hello Team,

Customer tested on gpio's toggle speed and the result shows around 400nS high and low period.

May i know the max speed gpio's toggle ?

thanks 

Best regards

  • 0
    Guru 117850 points

    It has been noted here (if memory serves) that the max (theoretical) speed of "GPIO Toggle" - that MCU - is "in the vicinity of 1/4th of MCU's System Clock.   (such resulted from MCU manual's listing of the requirement for: "2 system clock period's "GPIO high" and the same for "GPIO low.")      It is expected that 1/8th (15MHz) - even 1/16th (7.5MHz) - of MCU's System Clock - proves (more likely) to attain. 

    Program code impacts (ASM and DRM (direct register manipulation)) best enable such speed - use of the "high-speed GPIO Bus" - System Clock set to "spec's max" - and no unnecessary "pin loading" (especially capacitive) are required.    Use of a "short code loop" - rather than a "cascade of GPIO toggle instructions" - burdens the program - thus reduces GPIO toggle speed.

    No mention of "Customer's test methodology" (to include code) appears - such would prove helpful...     Note that an "MCU" proves sub-optimal for such, "high toggle rates" - FPGA/CPLD prove superior...

    I believe that such "GPIO bit banging" is "not" the best means to achieve, "highest toggle rate."     Instead - use of an MCU Timer - configured to PWM Mode - provides the highest, programmable, "GPIO toggle rate."