Trouble transitioning from NUCLEO-H7A3ZI-Q to custom STM32H7A3ZIT6 board (ADC stuck on LDORDY)

[edel-bel]

Hi everyone,

I'm new to Zephyr and currently working on a project that involves writing an application using it. While waiting for my custom board to arrive, I started development on a NUCLEO-H7A3ZI-Q. I’ve been able to read digital inputs and sample 3 ADC channels successfully on that board.

Now that my custom board is here (based on the STM32H7A3ZIT6 — without the "-Q" suffix), I expected the transition to be smooth, but I’ve run into some issues.

Key differences:
The custom board uses an 8 MHz crystal as the input frequency.

On the NUCLEO-H7A3ZI-Q, I had to use CONFIG_POWER_SUPPLY_DIRECT_SMPS.

On the custom board, I had to switch to CONFIG_POWER_SUPPLY_LDO.

The problem:
The Zephyr application does not reach main(). It seems to get stuck waiting for the LL_ADC_FLAG_LDORDY bit to be set. Here's a snippet from the GDB session:

Code
modules/hal/stm32/stm32cube/stm32h7xx/drivers/include/stm32h7xx_ll_adc.h:7552

7550 __STATIC_INLINE uint32_t LL_ADC_IsActiveFlag_LDORDY(const ADC_TypeDef *ADCx)
7551 {
7552 return ((READ_BIT(ADCx->ISR, LL_ADC_FLAG_LDORDY) == (LL_ADC_FLAG_LDORDY)) ? 1UL : 0UL);
7553 }

My configuration:

prj.conf

CONFIG_DEBUG=y
CONFIG_LOG=y
CONFIG_GPIO=y
CONFIG_SERIAL=y
CONFIG_UART_INTERRUPT_DRIVEN=y
CONFIG_PRINTK=y
CONFIG_PINCTRL=y
CONFIG_HEAP_MEM_POOL_SIZE=2048

# Clock
CONFIG_CLOCK_CONTROL=y
CONFIG_CLOCK_CONTROL_STM32_CUBE=y
CONFIG_CLOCK_STM32_HSE_CLOCK=8000000

# Power
CONFIG_POWER_SUPPLY_LDO=y

# ADC
CONFIG_ADC=y
CONFIG_ADC_ASYNC=y
CONFIG_ADC_STM32=y

board.dts

/ {
    model = "ST STM32H7A3ZIT6 board";
    compatible = "st,stm32h7a3";
};

&clk_hse {
    clock-frequency = <DT_FREQ_M(8)>;
    status = "okay";
};

&pll {
    div-m = <4>;
    mul-n = <128>;
    div-p = <2>;
    div-q = <2>;
    div-r = <2>;
    clocks = <&clk_hse>;
    status = "okay";
};

&rcc {
    status = "okay";
    clocks = <&pll>;
    clock-frequency = <DT_FREQ_M(128)>;
    d1cpre = <1>;
    hpre = <1>;
    d1ppre = <2>;
    d2ppre1 = <2>;
    d2ppre2 = <2>;
    d3ppre = <2>;
};

&adc1 {
    status = "okay";
    st,adc-clock-source = "SYNC";
    st,adc-prescaler = <4>;
    vref-mv = <1650>;
    pinctrl-0 = <&adc1_inp2_pf11 &adc1_inp4_pc4 &adc1_inp8_pc5>;
    pinctrl-names = "default";
};

Has anyone run into this issue before? Is there something I’m missing in the power or clock setup that could cause LDORDY to never be set?

Any help would be greatly appreciated!

Thanks in advance 🙏

[edel-bel]

Hi,

I found the culprit, the custom board had an issue generating the vref (and vdda). After having the board fixed, the ADC is working.

So no Zephyr issue :o)