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How to generate a sine wave with STM32?
In this LAB, we’ll discuss how to generate analog waveforms like (sine, sawtooth, triangular, etc) using STM32 PWM As a DAC with DMA transfer. And how to control the output waveform frequency. And also how to generate the waveform lookup table points for each function using MATLAB. Let’s get right into it!
How does the DMA trigger the PWM duty cycle?
Lastly, we can use the DMA & Timer to periodically trigger the DMA unit so that it moves a sample data point from the lookup table stored in memory to the PWM duty cycle control register (CCRx).
How to stop Hal PWM from starting DMA?
WORKAROUND: fill CCR1 (or Pulse value during init) register with pData [0] (partly described in HAL examples), pass &pData [1] to HAL_TIM_PWM_Start_DMA (not stated in HAL examples) and keep length at 5. The last idle cycle is cut in first transfer and occurred in the beginning of the subsequent transfer.
How are timer interrupts used in STM32?
Another way is to use Timer interrupts to periodically fire an interrupt signal so that the CPU can transfer the data points to the CCRx in a periodic manner. However, it’s a more efficient way than the previous one. But it still requires a lot of CPU intervention, especially when a high sampling rate is required.
How is a 50Hz sine wave generated in a PWM?
In our case will be generating a 50Hz sine wave using PWM signal generated by lpc2148 microcontroller. Now for a 50Hz sine wave we get a period time 1/50 = 20 milliseconds which is the time required for the sine wave to complete 1 full cycle.
How to calculate sine wave generation in C + +?
The maths sine function std::sin takes its argument in radians: If you need 1 cycle and 100 points then, knowing that there are 2pi radians in one cycle, you need something like If, on the off chance your compiler/library doesn’t have M_PI out of the box, then look here for flags that should make it available.
How to get a smooth output waveform?
To get the output waveform as smooth as possible we need to calculate the best possible divisions and resolution .. given we know the frequency of the output waveform. In our case will be generating a 50Hz sine wave using PWM signal generated by lpc2148 microcontroller.