• MCU: STM32F407VGT6
• Recommended framework: STM32 HAL
• Build system: STM32CubeIDE or PlatformIO with STM32Cube framework
• Clock assumption: configure HSE/PLL or HSI/PLL to a stable system clock; configure PA8 as MCO or timer/PWM clock output for the AD9833 MCLK requirement.

1. Initialize clocks and GPIO.
2. Assert AD7606 RESET pulse.
3. Configure AD9833 over SPI for sine output at 500kHz.
4. Arm acquisition timer for PRF = 100Hz.
5. On each 10ms period:
   • Start capture window.
   • Output TX trigger/blanking timing.
   • Generate or gate the five-cycle 10us burst.
   • Pulse AD7606 CONVST and read samples after BUSY falls.
6. Keep HV output disabled unless external interlocks and isolated power-good are valid.

C
#include "stm32f4xx_hal.h"
#include <stdint.h>

#define DDS_CS_PORT      GPIOA
#define DDS_CS_PIN       GPIO_PIN_4
#define DDS_MCLK_PORT    GPIOA
#define DDS_MCLK_PIN     GPIO_PIN_8

#define ADC_CS_PORT      GPIOB
#define ADC_CS_PIN       GPIO_PIN_12
#define ADC_BUSY_PORT    GPIOD
#define ADC_BUSY_PIN     GPIO_PIN_1
#define ADC_CONVST_PORT  GPIOD
#define ADC_CONVST_PIN   GPIO_PIN_0
#define ADC_RESET_PORT   GPIOD
#define ADC_RESET_PIN    GPIO_PIN_2

#define TX_TRIG_PORT     GPIOD
#define TX_TRIG_PIN      GPIO_PIN_3
#define TX_BLANK_PORT    GPIOD
#define TX_BLANK_PIN     GPIO_PIN_4
#define HV_STATUS_PORT   GPIOD
#define HV_STATUS_PIN    GPIO_PIN_5

SPI_HandleTypeDef hspi1; // AD9833 on PA5/PA7, software CS PA4
SPI_HandleTypeDef hspi2; // AD7606 on PB13/PB14/PB15, software CS PB12
TIM_HandleTypeDef htim_prf;

static void dds_write16(uint16_t word) {
    uint8_t tx[2] = { (uint8_t)(word >> 8), (uint8_t)(word & 0xFF) };
    HAL_GPIO_WritePin(DDS_CS_PORT, DDS_CS_PIN, GPIO_PIN_RESET);
    HAL_SPI_Transmit(&hspi1, tx, 2, HAL_MAX_DELAY);
    HAL_GPIO_WritePin(DDS_CS_PORT, DDS_CS_PIN, GPIO_PIN_SET);
}

static void ad9833_set_sine_500khz(uint32_t mclk_hz) {
    // AD9833 frequency word = fout * 2^28 / MCLK.
    uint32_t fw = (uint32_t)(((uint64_t)500000UL * 268435456ULL) / mclk_hz);
    dds_write16(0x2100); // reset + write frequency registers
    dds_write16(0x4000 | (fw & 0x3FFF));
    dds_write16(0x4000 | ((fw >> 14) & 0x3FFF));
    dds_write16(0xC000); // phase 0
    dds_write16(0x2000); // exit reset, sine output
}

static void ad7606_reset(void) {
    HAL_GPIO_WritePin(ADC_RESET_PORT, ADC_RESET_PIN, GPIO_PIN_SET);
    HAL_Delay(1);
    HAL_GPIO_WritePin(ADC_RESET_PORT, ADC_RESET_PIN, GPIO_PIN_RESET);
}

static void ad7606_start_conversion(void) {
    HAL_GPIO_WritePin(ADC_CONVST_PORT, ADC_CONVST_PIN, GPIO_PIN_SET);
    for (volatile int i = 0; i < 20; ++i) { __NOP(); }
    HAL_GPIO_WritePin(ADC_CONVST_PORT, ADC_CONVST_PIN, GPIO_PIN_RESET);
}

static void ad7606_read_two_lanes(uint16_t *douta, uint16_t *doutb, uint8_t count) {
    // For two-lane serial mode, 64 SCLK cycles read all 8 channels.
    // This placeholder uses SPI2 RX; exact dual-lane capture may need DMA or GPIO sampling for DOUTB.
    uint8_t rx[16] = {0};
    HAL_GPIO_WritePin(ADC_CS_PORT, ADC_CS_PIN, GPIO_PIN_RESET);
    HAL_SPI_Receive(&hspi2, rx, count * 2, HAL_MAX_DELAY);
    HAL_GPIO_WritePin(ADC_CS_PORT, ADC_CS_PIN, GPIO_PIN_SET);
    for (uint8_t i = 0; i < count; ++i) {
        douta[i] = ((uint16_t)rx[2*i] << 8) | rx[2*i + 1];
    }
    (void)doutb;
}

static void fire_burst_window(void) {
    HAL_GPIO_WritePin(TX_BLANK_PORT, TX_BLANK_PIN, GPIO_PIN_SET);
    HAL_GPIO_WritePin(TX_TRIG_PORT, TX_TRIG_PIN, GPIO_PIN_SET);
    // 500kHz five-cycle burst is 10us. Use a hardware timer in production.
    for (volatile int i = 0; i < 1000; ++i) { __NOP(); }
    HAL_GPIO_WritePin(TX_TRIG_PORT, TX_TRIG_PIN, GPIO_PIN_RESET);
    HAL_GPIO_WritePin(TX_BLANK_PORT, TX_BLANK_PIN, GPIO_PIN_RESET);
}

int main(void) {
    HAL_Init();
    SystemClock_Config();
    MX_GPIO_Init();
    MX_SPI1_Init();
    MX_SPI2_Init();
    MX_TIM_Init();

    HAL_GPIO_WritePin(DDS_CS_PORT, DDS_CS_PIN, GPIO_PIN_SET);
    HAL_GPIO_WritePin(ADC_CS_PORT, ADC_CS_PIN, GPIO_PIN_SET);
    HAL_GPIO_WritePin(TX_TRIG_PORT, TX_TRIG_PIN, GPIO_PIN_RESET);
    HAL_GPIO_WritePin(TX_BLANK_PORT, TX_BLANK_PIN, GPIO_PIN_RESET);

    ad7606_reset();
    ad9833_set_sine_500khz(25000000UL); // update if actual MCLK differs

    while (1) {
        if (HAL_GPIO_ReadPin(HV_STATUS_PORT, HV_STATUS_PIN) == GPIO_PIN_SET) {
            fire_burst_window();
        }
        ad7606_start_conversion();
        while (HAL_GPIO_ReadPin(ADC_BUSY_PORT, ADC_BUSY_PIN) == GPIO_PIN_SET) {}
        uint16_t samples_a[8], samples_b[8];
        ad7606_read_two_lanes(samples_a, samples_b, 8);
        HAL_Delay(10); // 100Hz PRF placeholder; replace with hardware timer for deterministic timing
    }
}

• The 10us burst timing and 100Hz PRF should be implemented with hardware timers, not delay loops, in production firmware.
• The Hamming window requires amplitude gating or DAC/amplifier control in the external HV module; if the external HV module only accepts trigger pulses, firmware can only time the burst, not shape the analog amplitude.
• Verify actual AD9833 MCLK frequency before calculating the frequency word.
• Verify AD7606 serial read mode in firmware against the final selected single-lane or dual-lane read strategy.