Clock Module

michael clark

Other Parts Discussed in Thread: MSP430F5529

I'm working on a sensor recording application with the MSP430f5529, SYS/BIOS 6.33.1.25 and XDCtools 3.22.1.12. I've been consistently experiencing unexpected behavior when toggling LED in a clock module SWI. This status is used to indicate that recording is enabled by using a toggle period of 2Hz. During recording, I've noticed changes in the period and duty cycle after running for a short time (<1min). I suspected that my processing load was high, but after disabling all sensors (i.e. interrupts) the behavior still exists.

I've now simplified my application to a few basic tasks: board init (clocks, pins, etc), SYS/BIOS start and one active clock SWI. There are no external interrupts and most on-chip subsystems are disabled. A SWI from the SYS/BIOS clock module is used to toggle the LED, which is enabled by default and initially works as expected. After a minute or so the SWI does not get executed with the correct period and duty cycle (2Hz, 50%).

At this point it seems the ACLK (32.768KHz) or SYS/BIOS clock module is not behaving as expected. Also this behavior is verified when toggling a GPIO in the clock SWI. Thinking this was a low-power mode issue, I removed the SYS/BIOS's MPS430 power management module, but nothing improved. The only way it seems to work is if I toggle the LED manually in a while loop in the main init SWI.

Any help would be appreciated.

over 13 years ago

0 ScottG over 13 years ago

TI__Mastermind 26780 points

Michael,

What do you observe when the LED or GPIO is toggling in an unexpected way?

If it is toggling at a very slow rate (about every 2 seconds)… I think the Clock module Swi may be held off too long after the timer interrupt occurs, and it gets in a wrap around mode. For MSP430 we have a Clock tick suppression feature that dynamically reprograms the underlying timer to interrupt on the next needed tick. This feature can significantly reduce CPU wakeups, but it brings some constraints regarding timely servicing of the timer tick, and execution of the Clock module’s Swi. (BTW, the Clock module uses a single Swi, which manages a queue of objects that represent functions to run at a particular tick counts.) These constraints are described here: http://processors.wiki.ti.com/index.php/SYS/BIOS_for_the_MSP430#Clock_Tick_Suppression

You might try selecting the pure “TickMode_PERIODIC” mode to see if this changes behavior: http://processors.wiki.ti.com/index.php/SYS/BIOS_for_the_MSP430#Switch_Clock_module_from_using_TickMode_DYNAMIC_to_TickMode_PERIODIC

That is the only idea I have at this point. If this is not it, please describe what you are seeing in more detail…

Thanks,
Scott

0 michael clark over 13 years ago in reply to ScottG

Intellectual 520 points

Adding "Clock.tickMode = Clock.TickMode_PERIODIC" fixed the problem.

Thanks!

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Clock Module