DevHeads IoT Integration Server•17mo ago

How to Fetch and Display Data from DHT22 Sensor on AVR32UC with Zephyr OS?

hey guys, still trying to advance on my work, I've been working on fetching and displaying data from the DHT22 sensor using the AVR32UC microcontroller, but I'm encountering a persistent data fetch failure.

Here’s the code I’ve implemented:

#include <zephyr.h>
#include <device.h>
#include <drivers/sensor.h>
#include <sys/printk.h>

const struct device *sensor_dev;

void main(void)
{
    struct sensor_value temp, humidity;

    sensor_dev = device_get_binding(DT_LABEL(DT_INST(0, ams_dht22)));
    if (!sensor_dev) {
        printk("Failed to bind DHT22 sensor\n");
        return;
    }

    if (sensor_sample_fetch(sensor_dev) < 0) {
        printk("Failed to fetch data\n");
        return;
    }

    sensor_channel_get(sensor_dev, SENSOR_CHAN_AMBIENT_TEMP, &temp);
    sensor_channel_get(sensor_dev, SENSOR_CHAN_HUMIDITY, &humidity);

    printk("Temperature: %d.%d C\n", temp.val1, temp.val2);
    printk("Humidity: %d.%d %%\n", humidity.val1, humidity.val2);
}

#include <zephyr.h>
#include <device.h>
#include <drivers/sensor.h>
#include <sys/printk.h>

const struct device *sensor_dev;

void main(void)
{
    struct sensor_value temp, humidity;

    sensor_dev = device_get_binding(DT_LABEL(DT_INST(0, ams_dht22)));
    if (!sensor_dev) {
        printk("Failed to bind DHT22 sensor\n");
        return;
    }

    if (sensor_sample_fetch(sensor_dev) < 0) {
        printk("Failed to fetch data\n");
        return;
    }

    sensor_channel_get(sensor_dev, SENSOR_CHAN_AMBIENT_TEMP, &temp);
    sensor_channel_get(sensor_dev, SENSOR_CHAN_HUMIDITY, &humidity);

    printk("Temperature: %d.%d C\n", temp.val1, temp.val2);
    printk("Humidity: %d.%d %%\n", humidity.val1, humidity.val2);
}

regardless of confirming the sensor's physical connections, verifying its initialization, ensuring the DHT22 sensor driver is correctly configured in

prj.conf

prj.conf

, and checking the device tree (

dts

dts

file) for accurate sensor definitions, I still receive the error

Failed to fetch data.

Failed to fetch data.

How can I successfully fetch and display temperature and humidity data from the DHT22 sensor on the AVR32UC microcontroller?

Solution

finally gushh

, I choked it, I enabled detailed logging, which revealed an I/O error. I then double-checked the GPIO configuration, verified d pin setup, and added a pull-up resistor. After increasing delays and adding debug prints in d driver code, I finally moved the sensor to a different GPIO pin. I think I'm making progress in this, the sensor is now successfully fetching and displaying data. see this

[00:00:00.000,000] <inf> dht: DHT driver initialized
[00:00:00.000,001] <dbg> dht: Starting data fetch
[00:00:00.000,002] <dbg> dht: Starting measurement
[00:00:00.000,003] <dbg> dht: Reading data
Temperature: 25.4 C
Humidity: 60.7 %

[00:00:00.000,000] <inf> dht: DHT driver initialized
[00:00:00.000,001] <dbg> dht: Starting data fetch
[00:00:00.000,002] <dbg> dht: Starting measurement
[00:00:00.000,003] <dbg> dht: Reading data
Temperature: 25.4 C
Humidity: 60.7 %

Jump to solution

SterlingAPP•8/6/24, 3:50 PM

@Dtynin Have you tried adding a debug prints inside the driver code to trace where the failure occurs. It's necessary to know if the driver is correctly communicating with the sensor.

Enthernet CodeAPP•8/6/24, 3:51 PM

hello @Dtynin did u wrap ur queue operations with mutex locks.
something like this

Enthernet CodeAPP•8/6/24, 3:51 PM

also check that your has a lower priority than since it operates less frequently and also handle errors by xQueueSend and xQueueReceive se the ESP32 debugging tools to identify the exact line where the crash occurs. The crash log suggests a memory access violation, which could be due to an invalid pointer or accessing memory out of bounds.

DtyninAPP•8/6/24, 4:05 PM

Thanks for getting back to me, @Enthernet Code I didn't use mutex locks in my implementation because I'm not working with FreeRTOS. Instead, I'm using Zephyr OS, which comes with its own synchronization tools. Here's my

prj.conf

prj.conf

file

I’ll try adding debug prints in the driver code next @Sterling

ZacckOsiemoAPP•8/6/24, 4:06 PM

Zephyr does support mutexes, along other tools as well.

DtyninAPP•8/8/24, 1:27 PM

You’re right @ZacckOsiemo , Zephyr does support mutexes along with other tools. But I opted to use Zephyr’s native sync mechanisms because they fit my needs better.

ZacckOsiemoAPP•8/8/24, 1:27 PM

that's valid.

Solution

DtyninAPP•8/8/24, 1:44 PM

finally gushh

[00:00:00.000,000] <inf> dht: DHT driver initialized
[00:00:00.000,001] <dbg> dht: Starting data fetch
[00:00:00.000,002] <dbg> dht: Starting measurement
[00:00:00.000,003] <dbg> dht: Reading data
Temperature: 25.4 C
Humidity: 60.7 %

[00:00:00.000,000] <inf> dht: DHT driver initialized
[00:00:00.000,001] <dbg> dht: Starting data fetch
[00:00:00.000,002] <dbg> dht: Starting measurement
[00:00:00.000,003] <dbg> dht: Reading data
Temperature: 25.4 C
Humidity: 60.7 %

DtyninAPP•8/8/24, 1:44 PM

merci guys:salute: