Problem with ADC on ULP RISC-V while deep-sleep
Posted: Sat Jun 21, 2025 1:06 pm
Hi all,
I am trying to write a simple program for reading ADC1CH6 while in deep sleep using ULP RISC-V.
For some reason, the "adc read" function is hanging. Removing it, I can verify that everything works well (going to sleep, setting variable on ULP and waking the main CPU, accessing the variable from the main program).
This is the main CPU code:
This is my ulp_main.c:
This is the config.h:
This is my sdkconfig.default:
This is the output from the serial:
I am trying to write a simple program for reading ADC1CH6 while in deep sleep using ULP RISC-V.
For some reason, the "adc read" function is hanging. Removing it, I can verify that everything works well (going to sleep, setting variable on ULP and waking the main CPU, accessing the variable from the main program).
This is the main CPU code:
Code: Select all
#include "config.h"
#include "esp_sleep.h"
#include "esp_timer.h"
#include <../include/driver/gpio.h>
#include "driver/rtc_io.h"
#include "esp_log.h"
#include "ulp_riscv.h"
#include "ulp_adc.h"
#include "esp_adc/adc_oneshot.h"
#include "ulp_main.h" // ULP program header (generated by esp-idf build system)
extern const uint8_t ulp_main_bin_start[] asm("_binary_ulp_main_bin_start");
extern const uint8_t ulp_main_bin_end[] asm("_binary_ulp_main_bin_end");
int counter = 0;
ulp_adc_cfg_t adc_config = {
.adc_n = ADC_UNIT,
.channel = ADC_CHANNEL,
.atten = ADC_ATTEN_DB_12,
.width = ADC_BITWIDTH_12,
.ulp_mode = ADC_ULP_MODE_RISCV,
};
void clear_ulp_adc_buffer() {
ulp_adc_buffer = 0;
}
void init_ulp() {
ESP_LOGI("MAIN", "First boot or other wakeup, initializing ULP");
ESP_ERROR_CHECK(ulp_adc_init(&adc_config));
ESP_ERROR_CHECK(ulp_riscv_load_binary(ulp_main_bin_start, (ulp_main_bin_end - ulp_main_bin_start)));
ESP_ERROR_CHECK(ulp_set_wakeup_period(0, 1000000));
clear_ulp_adc_buffer();
// Start ULP
ESP_LOGI("MAIN", "Starting ULP");
ESP_ERROR_CHECK(ulp_riscv_run());
}
extern "C" void app_main() {
esp_sleep_wakeup_cause_t wakeup_reason = esp_sleep_get_wakeup_cause();
ESP_LOGI("MAIN", "Wakeup cause: %d", wakeup_reason);
if (wakeup_reason == ESP_SLEEP_WAKEUP_UNDEFINED) init_ulp();
else ESP_LOGI("Wake up from ULP");
clear_ulp_adc_buffer();
// Enable ULP as wakeup source
ESP_LOGI("MAIN", "Enabling ULP as wakeup source and going to sleep");
ESP_ERROR_CHECK(esp_sleep_enable_ulp_wakeup());
esp_deep_sleep_start();
}
Code: Select all
#include "../src/config.h"
#include "ulp_riscv_adc_ulp_core.h"
#include "ulp_riscv_utils.h"
volatile int adc_buffer;
int main(void) {
adc_buffer = ulp_riscv_adc_read_channel(ADC_UNIT, ADC_CHANNEL);
ulp_riscv_wakeup_main_processor();
ulp_riscv_halt();
}
Code: Select all
#define ADC_CHANNEL ADC_CHANNEL_6
#define ADC_UNIT ADC_UNIT_1
Code: Select all
# Bootloader configuration
CONFIG_BOOTLOADER_SKIP_VALIDATE_IN_DEEP_SLEEP=y
# Additional power saving configurations
CONFIG_ESP_SLEEP_POWER_DOWN_FLASH=y
CONFIG_ESP_SLEEP_GPIO_RESET_WORKAROUND=y
CONFIG_ULP_COPROC_ENABLED=y
CONFIG_ULP_COPROC_TYPE_RISCV=y
CONFIG_ULP_COPROC_RESERVE_MEM=4096
What am I missing? Why is the ULP hang on reading ADC?I (294) MAIN: Wakeup cause: 0
I (294) MAIN: First boot or other wakeup, initializing ULP
I (304) MAIN: Starting ULP
I (304) MAIN: Enabling ULP as wakeup source and going to sleep
