/** * Copyright (c) 2021 Raspberry Pi (Trading) Ltd. * * SPDX-License-Identifier: BSD-3-Clause * */ #include <stdio.h> #include "pico/stdlib.h" #include "hardware/adc.h" /* Choose 'C' for Celsius or 'F' for Fahrenheit. */ #define TEMPERATURE_UNITS 'C' /* References for this implementation: * raspberry-pi-pico-c-sdk.pdf, Section '4.1.1. hardware_adc' * pico-examples/adc/adc_console/adc_console.c */ float read_onboard_temperature(const char unit) { /* 12-bit conversion, assume max value == ADC_VREF == 3.3 V */ const float conversionFactor = 3.3f / (1 << 12); float adc = (float)adc_read() * conversionFactor; float tempC = 27.0f - (adc - 0.706f) / 0.001721f; if (unit == 'C') { return tempC; } else if (unit == 'F') { return tempC * 9 / 5 + 32; } return -1.0f; } int main() { stdio_init_all(); #ifdef PICO_DEFAULT_LED_PIN gpio_init(PICO_DEFAULT_LED_PIN); gpio_set_dir(PICO_DEFAULT_LED_PIN, GPIO_OUT); #endif /* Initialize hardware AD converter, enable onboard temperature sensor and * select its channel (do this once for efficiency, but beware that this * is a global operation). */ adc_init(); adc_set_temp_sensor_enabled(true); adc_select_input(4); while (true) { float temperature = read_onboard_temperature(TEMPERATURE_UNITS); printf("Onboard temperature = %.02f %c\n", temperature, TEMPERATURE_UNITS); #ifdef PICO_DEFAULT_LED_PIN gpio_put(PICO_DEFAULT_LED_PIN, 1); sleep_ms(10); gpio_put(PICO_DEFAULT_LED_PIN, 0); #endif sleep_ms(990); } }

This firmware image was imported from the pico-examples repository. 


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