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As the kernel runs, physical memory becomes increasingly fragmented. Certain devices, such as those using DMA, require large contiguous physical memory blocks. When such memory is unavailable at runtime, the device may fail to operate. To address this, Linux provides a mechanism to reserve a dedicated region of physical memory for specific devi ...

DMA enables peripherals to transfer data directly between memory and hardware registers without CPU intervention. In Linux, DMA operations replace CPU-driven data writes to device registers, such as SPI_DATA for SPI communication, shifting from writel(data, SPI_DATA) to automated buffer transfers. Key considerations include address handling: CP ...

Configure the ADC to sample across 5 channels and enable DMA in circular mode. Buffer Definition and Initialization #define CHANNEL_COUNT 5 #define SAMPLES_PER_CHANNEL 100 static uint16_t raw_adc_buffer[CHAMPLES_PER_CHANNEL * CHANNEL_COUNT]; /** * @brief Initialize ADC calibration and start DMA transfer */ void ADC_Startup(void) { ...

Issue 1: Unexpected Data Transmission with DMA #include "stm32f10x.h" #include "Delay.h" #include "DMA.h" #include "Serial.h" uint8_t dataBuffer[3]; int main(void) { /* Module initialization */ OLED_Init(); Key_Init(); Serial_Init(); MyDMA_TX_Init(DMA1_Channel4, (uint32_t)&USART1- ...