AM2320 Sensor failing example

am2320.c

#include "am2320.h"

static uint16_t readRegister16(uint8_t reg);
static uint16_t crc16(uint8_t *buffer, uint8_t nbytes);

static void sensor_read() {
    sleep_ms(3000);
    am2320_data values;
    while (true) {
        sleep_ms(8000);
        printf("Reading Values... \n");
        values = am2320_read_data();
        printf("Temp: %f C\n", values.temp);
        printf("Humidity: %f%%\n", values.hum);
    }
}

void test_temp_sensor() {
    // Configure the I2C
    printf("Configuring I2C\n");
    i2c_init(DEFAULT_I2C_PORT, 400 * 1000);
    gpio_set_function(DEFAULT_SDA, GPIO_FUNC_I2C);
    gpio_set_function(DEFAULT_SCL, GPIO_FUNC_I2C);
    gpio_pull_up(DEFAULT_SDA);
    gpio_pull_up(DEFAULT_SCL);

    // initialize
    sensor_read();
}

am2320_data am2320_read_data() {
    // Create Empty sensor data
    am2320_data data = {.temp = -40.0, .hum = 0.0};

    // use an 8 byte buffer for sending and receiving data
    uint8_t buffer[8] = {0, 0, 0, 0, 0, 0, 0, 0};

    // write to the dht to wake it up
    i2c_write_blocking(DEFAULT_I2C_PORT, AM2320_ADDRESS, buffer, 1, false);
    sleep_ms(10);

    // send request to read all data from the dht (4 bytes of temp and hum data)
    uint8_t write_buff[3] = {AM2320_CMD_READREG, AM2320_START_ADDRESS, AM2320_DATA_END_ADDRESS};
    i2c_write_blocking(DEFAULT_I2C_PORT, AM2320_ADDRESS, write_buff, 3, true);
    sleep_ms(5);

    // dht sends us back 8 bytes, read them
    /*
     * Read out 8 bytes of data
     * Byte 0: Should be Modbus function code 0x03
     * Byte 1: Should be number of registers to read (0x04)
     * Byte 2: Humidity msb
     * Byte 3: Humidity lsb
     * Byte 4: Temperature msb
     * Byte 5: Temperature lsb
     * Byte 6: CRC lsb byte
     * Byte 7: CRC msb byte
     */
    i2c_read_blocking(DEFAULT_I2C_PORT, AM2320_ADDRESS, buffer, 8, false);

    // if echoed command was not to read 4 bytes of data registers, error
    printf("Is read addr correct: %d\n", buffer[0] == AM2320_ADDRESS || buffer[0] == _u(0x03));
    printf("[0x%02x 0x%02x  0x%02x 0x%02x  0x%02x 0x%02x  0x%02x 0x%02x]\n", buffer[0], buffer[1], buffer[2], buffer[3], buffer[4], buffer[5], buffer[6], buffer[7]);

    if (buffer[0] != AM2320_CMD_READREG || buffer[1] != AM2320_DATA_END_ADDRESS) {
        printf("Invalid data read!\n");
        return data;
    }

    // calulate checksum and compare vs recived checksum (2 last bytes)
    // if no match, error
    uint16_t the_crc = (buffer[7] << 8) | buffer[6];
    uint16_t calc_crc = crc16(buffer, 6);
    if (the_crc != calc_crc) {
        printf("CRC Checksum no match!\n");
        return data;
    }

    // extract the temp and hum data from recived data
    // temp: high is byte 4, low is byte 5
    // hum: high is byte 2, low is byte 3
    uint16_t tempData = (buffer[4] << 8) | buffer[5];
    uint16_t humData = (buffer[2] << 8) | buffer[3];

    // fill struct with temp and hum data by dividing recived values by 10,
    // clearing high of temp as it only communicates sign data
    data.temp = (tempData & 0x7FFF) / 10;
    data.hum = humData / 10;

    // if first bit of temp is set, it is negative
    if (tempData & 0x8000) {
        data.temp *= -1;
    }

    return data;
}

/**************************************************************************/
/*!
    @brief  perfor a CRC check to verify data
    @param buffer the pointer to the data to check
    @param nbytes the number of bytes to calculate the CRC over
    @return the calculated CRC
*/
/**************************************************************************/
static uint16_t crc16(uint8_t *buffer, uint8_t nbytes) {
    unsigned short crc = 0xFFFF;
    unsigned char i;
    while (nbytes--) {
        crc ^= *buffer++;
        for (i = 0; i < 8; i++) {
            if (crc & 0x01) {
                crc >>= 1;
                crc ^= 0xA001;
            } else {
                crc >>= 1;
            }
        }
    }
    return crc;
}

am2320.h

#pragma once

#include <hardware/i2c.h>
#include <pico/stdlib.h>
#include <stdio.h>

#define DEFAULT_SDA 10         // GPIO 10 (Physical PIN 14)
#define DEFAULT_SCL 11         // GPIO 11 (Pysical PIN 15)
#define DEFAULT_I2C_PORT i2c1  // i2c1 instance

#define AM2320_ADDRESS 0x5C           // < Address of sensor
#define AM2320_START_ADDRESS 0x00     // < start address of the data
#define AM2320_DATA_END_ADDRESS 0x04  // < end address of the temp & humidity data
#define AM2320_CMD_READREG 0x03       // < read register command
#define AM2320_REG_TEMP_H 0x02        // < high temp register address
#define AM2320_REG_HUM_H 0x00         // < high humidity register address

typedef struct {
    uint8_t address;   /**< i2c address of display*/
    i2c_inst_t *i2c_i; /**< i2c connection instance */
} am2320_t;

typedef struct {
    float temp;  // < temperature reading from the sensor in °C
    float hum;   // < humidity reading from the sensor
} am2320_data;

// Calling this in main to test it.
void test_temp_sensor();

am2320_data am2320_read_data();

main.c

#include <pico/cyw43_arch.h>
#include <pico/stdlib.h>

#include "am2320.h"

int main() {
    stdio_init_all();  // Initialize

    printf("Main Program Executation start!\n");

    // Testing the sensor here
    test_temp_sensor();

    return 0;
}