Currently I am using FTM timers to generate few bytes of data by toggling a pin.
But this consumes lot of CPU cycles. The signal which is generated using the FTM timer has a logic 1 for a signal which is atleast 40us held high.
I want to replace FTM using the DMA, for this I built a simple example where I try to set a port pin to high.
I am using MKV10Z64VLF7 microcontroller. The port pin I want to toggle is PTB 17.
Here is the code I used :
#include "fsl_edma.h"
#include "fsl_dmamux.h"
// Define the GPIO port and pin number to toggle
#define GPIO_PORT GPIOB
#define GPIO_PIN 17U
#define DMA_CHANNEL_NUMBER 5 // Replace 0 with the desired DMA channel number
// Define the memory buffer with the data to toggle the pin
// In this example, we use a single 32-bit word where bit 0 controls the GPIO_PIN
uint32_t edmaToggleBuffer = 0xFFFFFFFF;
// Flag to track if the DMA configuration has been done
bool dmaConfigured = false;
void configureEDMAToggle(DMA_Type *dmaBase)
{
// Initialize the DMAMUX module if required (usually done in the system initialization)
DMAMUX_Init(DMAMUX0);
// Enable the DMA channel in the DMAMUX
DMAMUX_EnableChannel(DMAMUX0, DMA_CHANNEL_NUMBER);
// Initialize the eDMA module with default configuration
edma_config_t dmaConfig;
EDMA_GetDefaultConfig(&dmaConfig);
EDMA_Init(dmaBase, &dmaConfig);
// Create an eDMA handle (if required) - Check your SDK documentation
edma_handle_t edmaHandle;
EDMA_CreateHandle(&edmaHandle, dmaBase, DMA_CHANNEL_NUMBER);
// Set up the eDMA transfer
edma_transfer_config_t transferConfig;
EDMA_PrepareTransfer(&transferConfig, &edmaToggleBuffer, sizeof(uint32_t),
(void *)(&(GPIO_PORT->PDOR)), sizeof(uint32_t),
sizeof(uint32_t), sizeof(uint32_t), kEDMA_MemoryToPeripheral);
// Submit the transfer configuration to the eDMA channel (if required) - Check your SDK documentation
EDMA_SubmitTransfer(&edmaHandle, &transferConfig);
// Enable the eDMA channel request (if required) - Check your SDK documentation
EDMA_StartTransfer(&edmaHandle);
// Set the flag to indicate that the DMA has been configured
dmaConfigured = true;
}
void main (void)
{
// Check if DMA configuration is done
if (dmaConfigured == false) {
// Toggle the GPIO pin using DMA for the first time only
configureEDMAToggle(DMA0);
}
}
