I’d like to interface with the TLC5940 LED driver chip. The chip lacks an internal clock so it relies on an external blanking signal from the microcontroller every couple hundred picoseconds. I’d like to issue the blanking signal via a periodic interrupt handler. What is the best way to configure th…

The Spark Core firmware indeed uses Hardware Timers to generate PWM outputs via the following Wiring APIs: 1)analogWrite(pin, value) [Refer spark_wiring.c] This produces a fixed frequency of 500Hz with configurable duty cycle[0-100%] 2)Servo::writeMicroseconds(pulseWidth) [Refer spark_wiring_servo…

Thanks for the follow up. I still need to trigger an interrupt on a timer to periodically copy a the frame buffer into the TLC5940 over the SPI bus. I can send the blanking signal to the chip after the copy is complete. This way I don’t have to use any PWM and can instead reuse TIM4 to triger the in…

Ok to bind an interrupt handler for TIM4, Please follow these steps: 1)You need to override the TIM4_IRQHandler which is defined as weak in startup code. For this in your application, define a function: void TIM4_IRQHandler(void) { //Your interrupt handler code should look something like this. …

I seem to be having some issues when enabling timer-based interrupts. I have been looking at your example, and the tutorial Controlling STM32 Hardware Timers with Interrupts – VisualGDB Tutorials , and I can't seem to get the interrupt handler working. After initializing the timer, I have the follow…

So you are using TIM2. Did you change the default priority grouping since I see this in your code. nvicStructure.NVIC_IRQChannelSubPriority = 1; Do you have this statement in your code: TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE); Try adding this declaration in your stm32_it.h file: void TIM2_IRQH…

I was experimenting with changing the priority grouping, although I changed it back to 0 so we are both on the same page. And yes, I have TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE); in my code. I just tried adding void TIM2_IRQHandler(void); to stm32_it.h, but unfortunately it did not seem to fix th…

Can you send me the complete code related to TIM2 usage? Thanks

Ok. Resolved. This was a linking issue. Since application is .cpp file, you require extern “C” before your Interrupt handler definition. So your TIM2 interrupt handler code should look like: extern “C” void TIM2_IRQHandler(void) { … }

Would love to see the full source for this. I want to control my own TLC5940. Plus I want a better understanding of SPI to understand other SPI chips.

I’m having the same problem that @mb3 was – The interrupt handler is not binding. I can call it directly from loop, but if I try to do all the NVIC stuff it’ll compile but the timer update event won’t actually trigger the handler. I see that @mb3 ’s solution was to compile with extern "C", but he no…

Creating timer-based interrupts

Firmware

bko March 29, 2014, 3:49am 12

Hi @kmarsh

Did you see this link:

And this nice new library from @peekay123

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Creating timer-based interrupts

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