CC2530: Zstack interfering with regular code

MANISH KUMAR

Part Number: CC2530
Other Parts Discussed in Thread: Z-STACK,

I am using TI CC2530 with zigbee 3.0.1 Z-stack. I am trying to generate a 5 kHz 50% duty cycle pulse using hardware timer interrupts. Expected waveform is as shown below:

However, I see some jitter in the signal. My half wave (which should measure 100 uS) comes out between 70 uS (minimum) to 130 uS (maximum). Somewhat like as shown below:

Jitter value (60 uS) doesn't change if I change the base frequency (currently 5 kHz) or the duty cycle (currently 50%).

However, if I comment out zigbee tasks, I get perfect waveform as expected. I feel that zigbee tasks somehow interferes with my timer interrupts due to which I am not able to keep correct track of time and hence not able to generate the exact waveform. Is there a workaround which I can implement to get rid of this problem? I need zigbee communication so can't disable it.

over 8 years ago

0 MANISH KUMAR over 8 years ago

Intellectual 275 points

YiKai Chen Can you please help with this?

0 YiKai Chen over 8 years ago in reply to MANISH KUMAR

Guru 735695 points

How do you output PWM?

0 MANISH KUMAR over 8 years ago in reply to YiKai Chen

Intellectual 275 points

Im generating the PWM by starting a timer in modulo compare value mode where it starts the counter and matches with compare registers and generates interrupt and then again resets the counter to 0. Whenever i get the interrupt i toggle the pin. This pin is attached to oscilloscope and checked.

In the code when i disable the osal_start_system line, the generated pulse is perfect but when i enable the osal_start_system, the generated pulse is oscillating.

0 YiKai Chen over 8 years ago

Guru 735695 points

Try to refer to sunmaysky.blogspot.tw/.../how-to-output-pwm-from-cc2530.html which shows you how to output PWM.

0 MANISH KUMAR over 8 years ago in reply to YiKai Chen

Intellectual 275 points

Ok, my actual task is not generating PWM, it is to do phase dimming. I did this PWM test to test if the timer is perfect. Also my dimming works perfectly when i disable the osal_start_system().

1. Interrupt on a pin (zero cross).
2. On this interrupt i start a timer for 8ms( can vary from 2ms - 9ms depending on dim level).
3. When the timer completes i get an interrupt on which i turn a pin high and start a new timer for 100 microseconds.
4. when the 100 microseconds timer stops and generates another interrupt i need to turn the pin low.

It is guaranteed that there won't be another interrupt from zerocross before 10ms. This same activity needs to be performed everytime the zero cross generates a interrupt which is every 10ms (will vary a bit and hence need to be in sync with the interrupt generated from it).

0 YiKai Chen over 8 years ago in reply to MANISH KUMAR

Guru 735695 points

It's not recommended to use CC2530 to do such time critical job. I would suggest you to use an extra MSP430 to do it.

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CC2530: Zstack interfering with regular code