Hardware Peripheral Drivers

SyntropicOS provides portable hardware abstraction drivers for GPIO, UART, ADC, DAC, CAN, SPI, I2C, RTC, and DMA. Every driver is guarded by compile-time configuration switches (SYN_USE_*).

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Technical Specifications

Feature	Specification
Port Interface	Hardware-independent wrapper calling syn_port_* interfaces.
ISR Safety	UART and DMA drivers use lock-free SPSC ring buffers for safe ISR-to-task transfers.
Memory Allocation	100% Static / Zero Heap. All driver instances are caller-owned structures.

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Driver Dataflow Pipeline (UART + DMA Example)

flowchart LR
    HW["Hardware Peripheral (UART / ADC)"] -- ISR / DMA Interrupt --> RingBuf["SPSC Ring Buffer (syn_ringbuf)"]
    RingBuf -- syn_uart_read() --> Task["Cooperative Protothread Task"]
    Task --> Processing["Process Byte Stream"]

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1. GPIO & Digital I/O (drivers/syn_gpio.h)

Provides pin initialization, reading, writing, toggling, and mode configuration (Input, Output, Pull-Up, Pull-Down, Open-Drain).

#include <syntropic/drivers/syn_gpio.h>

void gpio_demo(void) {
    // Initialize pin 13 as Output
    syn_gpio_init(13, SYN_GPIO_OUTPUT);

    // Toggle pin state
    syn_gpio_toggle(13);

    // Read input level
    SYN_GPIO_State state = syn_gpio_read(12);
}

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2. Buffered Serial UART (drivers/syn_uart.h)

Buffered UART driver using lock-free SPSC ring buffers for high-speed RX/TX without data loss.

#include <syntropic/drivers/syn_uart.h>

static uint8_t rx_buf[128];
static uint8_t tx_buf[128];
static SYN_UART uart;

void uart_setup(void) {
    // Initialize UART 1 at 115200 8N1
    syn_uart_init(&uart, 1, 115200, rx_buf, sizeof(rx_buf), tx_buf, sizeof(tx_buf));
}

void USART1_IRQHandler(void) {
    // ISR feed: safe to call from interrupt context
    uint8_t rx_byte = (uint8_t)USART1->DR;
    syn_uart_isr_rx_byte(&uart, rx_byte);
}

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3. Analog-to-Digital Converter (drivers/syn_adc.h)

Provides ADC sampling with oversampling, EMA filtering, voltage conversion (mV), and signal statistics integration.

#include <syntropic/drivers/syn_adc.h>

static SYN_ADC adc_ch0;

void adc_setup(void) {
    SYN_ADC_Config cfg = {
        .channel = 0,
        .oversample = 4, // 4x oversampling for noise reduction
        .filter = NULL
    };
    syn_adc_init(&adc_ch0, &cfg);
}

void read_voltage(void) {
    syn_adc_read(&adc_ch0);
    uint32_t millivolts = syn_adc_millivolts(&adc_ch0);
    printf("Channel 0: %lu mV\n", (unsigned long)millivolts);
}

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4. DMA Transaction Engine (drivers/syn_dma.h)

Bare-metal safe DMA transaction engine featuring address alignment verification, D-cache invalidation, and atomic busy protection.

#include <syntropic/drivers/syn_dma.h>

static SYN_DMA dma;

void on_dma_complete(SYN_DMA *dma_inst, void *ctx) {
    printf("DMA Transfer Complete!\n");
}

void start_dma_transfer(const uint32_t *src, uint32_t *dst, size_t count) {
    syn_dma_init(&dma, 0, on_dma_complete, NULL);
    syn_dma_start(&dma, (const void*)src, (void*)dst, count * sizeof(uint32_t));
}