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July 16, 2026
Question
STM32N657X0-Q: ADC1 Calibration fails (HAL_ERROR 1) and returns 0 despite RIFSC Non-Secure configuration and CN12 jumpers connected
- July 16, 2026
- 2 replies
- 27 views
Hi ST Community,
I am currently working on an analog sensor acquisition project using the NUCLEO-N657X0-Q (STM32N657X0) board on STM32CubeIDE (version 1.19.0). I am attempting to read a Keyes pressure sensor via ADC1 on PA1 (ADC1_INP1).
Physical Wiring & Setup
-
Sensor Connections: The pressure sensor is physically wired to:
-
VCC -> Board 3.3V
-
GND -> Board GND
-
Signal Out -> PA1 (bridged with a 1/2 resistor divider to ground to ensure the voltage never exceeds 1.8V).
-
-
CN12 Jumpers Connected:
-
Pin 13 / Pin 14 (VDDA1V8) is connected with a jumper cap to supply 1.8V to VDDA.
-
Pin 11 / Pin 12 (VDDIO) is connected with a jumper cap.
-
STM32CubeMX Configurations
-
VREFBUF: Configured as Disable (since the NUCLEO board provides an external 1.8V reference to
VREF+). -
Security & RIF (RIFSC Panel):
-
ADC1: Configured as Non-Secure, Unprivileged (unchecked), Unlock (unchecked), and assigned to the Application context.
-
GPIOA: Configured as Non-Secure, Unprivileged (unchecked), and assigned to the Application context.
-
-
ADC1 Parameters: 12-bit Resolution, Scan Conversion Mode Disabled, Continuous Conversion Mode Disabled, Software Trigger.
Symptom & Error Logs
During system startup, HAL_ADCEx_Calibration_Start(&hadc1, ADC_SINGLE_ENDED) consistently fails and returns HAL_ERROR (Status Code 1).
When running the main loop, the returned values are always 0:
============================================
STM32N657X0-Q Keyes Pressure Sensor Demo
System Core Clock: 64000000 Hz
============================================
[VREF] NUCLEO-N657X0-Q board provides an external 1.8V analog reference (VREF+).
[VREF] Software bypassed VREFBUF (Disabled) to avoid Secure World register lock.
[ADC1] Starting hardware self-calibration...
[ADC1] WARNING: Calibration failed! Error Code: 1
-> 🚨 Please troubleshoot based on the following checklist:
1. [JUMPERS] Verify CN12 Pin 13 & Pin 14 (VDDA1V8) are connected with a jumper cap.
(R104 is OFF by default; bridging CN12 13-14 is mandatory to power the analog core!)
2. [JUMPERS] Verify CN12 Pin 11 & Pin 12 (VDDIO) are connected with a jumper cap.
3. [FIREWALL] Confirm ADC1 and GPIOA are configured as Non-Secure / Unprivileged in CubeMX RIF Panel.
4. [CLOCKS] Ensure 'ADC Source Mux' is pointing to a valid clock (e.g. HSIDIV, CLK_KER <= 50MHz).
[Keyes Sensor] RAW Value: 0 | Calculated Voltage: 0.000 V
[Keyes Sensor] RAW Value: 0 | Calculated Voltage: 0.000 V💻 Code Snippet (main.c)
Here is my non-secure application code used for sampling:
/* USER CODE BEGIN Header */
/**
******************************************************************************
* @file : main.c
* @brief : Main program body - ADC1 Pressure Sensor Sampling
******************************************************************************
* @attention
*
* Copyright (c) 2026 STMicroelectronics.
* All rights reserved.
*
* This software is licensed under terms that can be found in the LICENSE file
* in the root directory of this software component.
* If no LICENSE file comes with this software, it is provided AS-IS.
*
******************************************************************************
*/
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include <stdio.h> // Include standard I/O library for printf support
/* USER CODE END Includes */
/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */
/* USER CODE END PTD */
/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */
/* USER CODE END PD */
/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */
/* USER CODE END PM */
/* Private variables ---------------------------------------------------------*/
ADC_HandleTypeDef hadc1;
UART_HandleTypeDef huart1;
/* USER CODE BEGIN PV */
uint32_t adc_raw_val = 0; // Stores 12-bit raw ADC reading (0 ~ 4095)
float sensor_voltage = 0.0f; // Stores physical voltage (V) after 1/2 divider compensation
/* USER CODE END PV */
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_ADC1_Init(void);
static void MX_USART1_Init(void);
/* USER CODE BEGIN PFP */
float Read_Keyes_Pressure_PA1(void); // Function prototype for pressure sensor reading
/* USER CODE END PFP */
/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
#ifdef __GNUC__
/* Redirect __io_putchar to UART register for GCC compilers */
#define PUTCHAR_PROTOTYPE int __io_putchar(int ch)
#else
#define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f)
#endif
PUTCHAR_PROTOTYPE
{
/* Transmit one character via USART1 with max delay timeout */
HAL_UART_Transmit(&huart1, (uint8_t *)&ch, 1, HAL_MAX_DELAY);
return ch;
}
/* Overwrite standard write function to ensure smooth float and string printf output */
int _write(int file, char *ptr, int len)
{
HAL_UART_Transmit(&huart1, (uint8_t *)ptr, len, HAL_MAX_DELAY);
return len;
}
/* USER CODE END 0 */
/**
* @brief The application entry point.
* @retval int
*/
int main(void)
{
/* USER CODE BEGIN 1 */
/* USER CODE END 1 */
/* MCU Configuration--------------------------------------------------------*/
/* Reset of all peripherals, Initializes the Flash interface and the Systick. */
HAL_Init();
/* USER CODE BEGIN Init */
/* USER CODE END Init */
/* Configure the system clock */
SystemClock_Config();
/* USER CODE BEGIN SysInit */
/* USER CODE END SysInit */
/* Initialize all configured peripherals */
MX_GPIO_Init();
MX_ADC1_Init();
MX_USART1_Init();
/* USER CODE BEGIN 2 */
/* --- [1] Initialize Serial Terminal Header --- */
printf("\r\n============================================\r\n");
printf(" STM32N657X0-Q Keyes Pressure Sensor Demo\r\n");
printf(" System Core Clock: %lu Hz\r\n", HAL_RCC_GetSysClockFreq());
printf("============================================\r\n");
/* --- [2] Reference Voltage Mode Notification --- */
printf("[VREF] NUCLEO-N657X0-Q board provides an external 1.8V analog reference (VREF+).\r\n");
printf("[VREF] Software bypassed VREFBUF (Disabled) to avoid Secure World register lock.\r\n");
/* --- [3] Stabilization Delay --- */
// Delay 50ms to ensure VDDA1V8 power rail and clock supply are fully stabilized
HAL_Delay(50);
/* --- [4] STM32N657X0 Hardware Self-Calibration --- */
printf("[ADC1] Starting hardware self-calibration...\r\n");
HAL_StatusTypeDef cal_status = HAL_ADCEx_Calibration_Start(&hadc1, ADC_SINGLE_ENDED);
if (cal_status != HAL_OK)
{
printf("[ADC1] WARNING: Calibration failed! Error Code: %d\r\n", cal_status);
printf(" -> 🚨 Please troubleshoot based on the following checklist:\r\n");
printf(" 1. [JUMPERS] Verify CN12 Pin 13 & Pin 14 (VDDA1V8) are connected with a jumper cap.\r\n");
printf(" (R104 is OFF by default; bridging CN12 13-14 is mandatory to power the analog core!)\r\n");
printf(" 2. [JUMPERS] Verify CN12 Pin 11 & Pin 12 (VDDIO) are connected with a jumper cap.\r\n");
printf(" 3. [FIREWALL] Confirm ADC1 and GPIOA are configured as Non-Secure / Unprivileged in CubeMX RIF Panel.\r\n");
printf(" 4. [CLOCKS] Ensure 'ADC Source Mux' is pointing to a valid clock (e.g. HSIDIV, CLK_KER <= 50MHz).\r\n");
}
else
{
printf("[ADC1] Calibration successful! System is ready for data acquisition.\r\n");
}
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
/* --- [5] Periodic Sampling and Logging --- */
sensor_voltage = Read_Keyes_Pressure_PA1();
// Log formatted data
printf("[Keyes Sensor] RAW Value: %4lu | Calculated Voltage: %.3f V\r\n",
adc_raw_val, sensor_voltage);
// Delay 250ms to prevent flooding the terminal
HAL_Delay(250);
/* USER CODE END WHILE */
/* USER CODE BEGIN 3 */
}
/* USER CODE END 3 */
}
/**
* @brief System Clock Configuration
* @retval None
*/
void SystemClock_Config(void)
{
RCC_OscInitTypeDef RCC_OscInitStruct = {0};
RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
/** Configure the main internal regulator output voltage
*/
if (HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1) != HAL_OK)
{
Error_Handler();
}
/** Initializes the RCC Oscillators according to the specified parameters
* in the RCC_OscInitTypeDef structure.
*/
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
RCC_OscInitStruct.HSIState = RCC_HSI_ON;
RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
Error_Handler();
}
/** Initializes the CPU, AHB and APB buses clocks
*/
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2
|RCC_CLOCKTYPE_PCLK4|RCC_CLOCKTYPE_PCLK5;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;
RCC_ClkInitStruct.AHBCLKDivider = RCC_HCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
RCC_ClkInitStruct.APB4CLKDivider = RCC_HCLK_DIV1;
RCC_ClkInitStruct.APB5CLKDivider = RCC_HCLK_DIV1;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct) != HAL_OK)
{
Error_Handler();
}
}
/**
* @brief ADC1 Initialization Function
* @param None
* @retval None
*/
static void MX_ADC1_Init(void)
{
/* USER CODE BEGIN ADC1_Init 0 */
/* USER CODE END ADC1_Init 0 */
ADC_ChannelConfTypeDef sConfig = {0};
/* USER CODE BEGIN ADC1_Init 1 */
/* USER CODE END ADC1_Init 1 */
/** Common config
*/
hadc1.Instance = ADC1;
hadc1.Init.Resolution = ADC_RESOLUTION_12B;
hadc1.Init.ScanConvMode = ADC_SCAN_DISABLE;
hadc1.Init.EOCSelection = ADC_EOC_SINGLE_CONV;
hadc1.Init.LowPowerAutoWait = DISABLE;
hadc1.Init.ContinuousConvMode = DISABLE;
hadc1.Init.NbrOfConversion = 1;
hadc1.Init.DiscontinuousConvMode = DISABLE;
hadc1.Init.ExternalTrigConv = ADC_SOFTWARE_START;
hadc1.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE;
hadc1.Init.Overrun = ADC_OVR_DATA_PRESERVED;
hadc1.Init.OversamplingMode = DISABLE;
if (HAL_ADC_Init(&hadc1) != HAL_OK)
{
Error_Handler();
}
/** Configure Regular Channel
*/
sConfig.Channel = ADC_CHANNEL_1;
sConfig.Rank = ADC_REGULAR_RANK_1;
sConfig.SamplingTime = ADC_SAMPLETIME_11CYCLES_5;
sConfig.SingleDiff = ADC_SINGLE_ENDED;
sConfig.OffsetNumber = ADC_OFFSET_NONE;
sConfig.Offset = 0;
if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN ADC1_Init 2 */
/* USER CODE END ADC1_Init 2 */
}
/**
* @brief USART1 Initialization Function
* @param None
* @retval None
*/
static void MX_USART1_Init(void)
{
/* USER CODE BEGIN USART1_Init 0 */
/* USER CODE END USART1_Init 0 */
/* USER CODE BEGIN USART1_Init 1 */
/* USER CODE END USART1_Init 1 */
huart1.Instance = USART1;
huart1.Init.BaudRate = 115200;
huart1.Init.WordLength = UART_WORDLENGTH_8B;
huart1.Init.StopBits = UART_STOPBITS_1;
huart1.Init.Parity = UART_PARITY_NONE;
huart1.Init.Mode = UART_MODE_TX_RX;
huart1.Init.HwFlowCtl = UART_HWCONTROL_NONE;
huart1.Init.OverSampling = UART_OVERSAMPLING_16;
huart1.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
huart1.Init.ClockPrescaler = UART_PRESCALER_DIV1;
huart1.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
if (HAL_UART_Init(&huart1) != HAL_OK)
{
Error_Handler();
}
if (HAL_UARTEx_SetTxFifoThreshold(&huart1, UART_TXFIFO_THRESHOLD_1_8) != HAL_OK)
{
Error_Handler();
}
if (HAL_UARTEx_SetRxFifoThreshold(&huart1, UART_RXFIFO_THRESHOLD_1_8) != HAL_OK)
{
Error_Handler();
}
if (HAL_UARTEx_DisableFifoMode(&huart1) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN USART1_Init 2 */
/* USER CODE END USART1_Init 2 */
}
/**
* @brief GPIO Initialization Function
* @param None
* @retval None
*/
static void MX_GPIO_Init(void)
{
/* USER CODE BEGIN MX_GPIO_Init_1 */
/* USER CODE END MX_GPIO_Init_1 */
/* GPIO Ports Clock Enable */
__HAL_RCC_GPIOE_CLK_ENABLE();
__HAL_RCC_GPIOA_CLK_ENABLE();
/* USER CODE BEGIN MX_GPIO_Init_2 */
/* USER CODE END MX_GPIO_Init_2 */
}
/* USER CODE BEGIN 4 */
/**
* @brief Reads PA1 (ADC1_INP1) pressure sensor voltage and prints diagnostics.
* @note STM32N657X0 ADC Reference (VREF+) is 1.8V.
* If the external hardware uses a 1/2 resistor divider to ground (protecting PA1 from >1.8V),
* this algorithm multiplies by 2.0f to reconstruct the true sensor voltage on 3.3V power rail.
* @retval float Compensated real voltage (V)
*/
float Read_Keyes_Pressure_PA1(void)
{
uint32_t raw_data = 0;
float calculated_vol = 0.0f;
HAL_StatusTypeDef start_status;
HAL_StatusTypeDef poll_status;
// 1. Start ADC1 Single conversion (Software trigger)
start_status = HAL_ADC_Start(&hadc1);
if (start_status == HAL_OK)
{
// 2. Poll for ADC conversion completion with 20ms timeout defense
poll_status = HAL_ADC_PollForConversion(&hadc1, 20);
if (poll_status == HAL_OK)
{
// 3. Read 12-bit ADC conversion result (0 ~ 4095)
raw_data = HAL_ADC_GetValue(&hadc1);
adc_raw_val = raw_data; // Synchronize to global variable
// 4. Reconstruct sensor output voltage
// Formula: (ADC raw / 4095) * ADC Reference (1.8V) * Divider compensation (2.0)
calculated_vol = ((float)raw_data / 4095.0f) * 1.8f * 2.0f;
}
else
{
// Diagnostic output on poll failure (capped at once every 5 seconds to prevent spam)
static uint32_t last_poll_log = 0;
if (HAL_GetTick() - last_poll_log > 5000)
{
printf("[ADC1 Log] PollForConversion Failed! HAL Status: %d\r\n", poll_status);
printf(" -> Ensure the clock tree 'ADC Source Mux' is correctly configured (e.g., HSIDIV).\r\n");
last_poll_log = HAL_GetTick();
}
}
// 5. Stop ADC conversion to save power and prepare for next iteration
HAL_ADC_Stop(&hadc1);
}
else
{
// Diagnostic output on start failure (capped at once every 5 seconds)
static uint32_t last_start_log = 0;
if (HAL_GetTick() - last_start_log > 5000)
{
printf("[ADC1 Log] HAL_ADC_Start Failed! HAL Status: %d\r\n", start_status);
printf(" -> Register write blocked! Verify RIFSC permissions for ADC1 and GPIOA are assigned to Application.\r\n");
last_start_log = HAL_GetTick();
}
}
return calculated_vol;
}
/* USER CODE END 4 */
/**
* @brief This function is executed in case of error occurrence.
* @retval None
*/
void Error_Handler(void)
{
/* USER CODE BEGIN Error_Handler_Debug */
/* User can add his own implementation to report the HAL error return state */
__disable_irq();
while (1)
{
}
/* USER CODE END Error_Handler_Debug */
}
#ifdef USE_FULL_ASSERT
/**
* @brief Reports the name of the source file and the source line number
* where the assert_param error has occurred.
* @param file: pointer to the source file name
* @param line: assert_param error line source number
* @param retval None
*/
void assert_failed(uint8_t *file, uint32_t line)
{
/* USER CODE BEGIN 6 */
/* User can add his own implementation to report the file name and line number,
ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
/* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */
Questions
Since the RIFSC has already been configured to assign ADC1 and GPIOA to the Non-Secure Application context, and the physical power rails are properly jumpered:
-
Is there any additional system power configuration (e.g., PWR or clock gating) required to enable the ADC1 analog domain or internal voltage regulator for non-secure applications on STM32N6?
-
Does the STM32N6 ADC hardware calibration require specific clock speed constraints or a specific prescaler setup to pass?
Any advice, hints, or ADC reference examples for the STM32N6 series would be highly appreciated.
Best regards,
