NRF52840 Dongle with DHT-11 Sensor with OpenThread Network

[jonathanljc]

How can i configure the nrf52840 dongle with DHT-11 sensor such that i am able to use it to send the temperature data via UDP within the Thread Network?

I am using the NRF52840 dongles, and not using the DK board. Anyways i can mitigate it or reference for configuration? I tend to use the pin 0.02 for the data output connecting to the DHT-11 sensor to my Dongle. Thank you. 

[runsiv]

Hi

Just so that I know where to start. Do you have the DHT-11 up and running with Zephyr and the dongle? From what I can see I don't see any issue with using pin 0.02 as I can't see it is used for anything else on the dongle. 

Regards

Runar

[jonathanljc]

Hi Runsiv, 

the issues is that the Zephyr dht sample is for DHT-22 instead and not DHT-11. I have not tried starting up the above mention and running with the Zephyr and the dongle. 

below is my main.c of my openthread network sending randomize value acting as temperature sensor via udp to my Thread Border Router within the Thread Network.

I got it running up and its able to send and my Thread Border is able to receive. by opening the udp port "1234" on my thread border router (RPI4). So now i want to integrate with DHT-11 Sensor, but there isnt any tutorial or so to setup.

Reference link to the sample DHT-22 of the Zephyr:

github.com/.../dht

/*
 * Copyright (c) 2020 Nordic Semiconductor ASA
 *
 * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
 */

#include <zephyr/kernel.h>
#include <stdio.h>
#include <stdlib.h>
#include <zephyr/logging/log.h>
#include <openthread/platform/radio.h>
#include <openthread/thread.h>
#include <openthread/udp.h>
#include <zephyr/drivers/uart.h>
#include <zephyr/usb/usb_device.h>

static const char UDP_DEST_ADDR[] = "fd40:3477:6aa4:1:9da4:1bf2:475e:efe9";  // IPv6 Address of OTBR
// fd34:3efd:9d7:1:b089:a484:57bd:518f // IPv6 Address of OTBR Jon

static const uint16_t UDP_PORT = 1234;  // Choose a suitable UDP port

static char udpPayload[50];  // Payload to send over UDP

void generateRandomPayload(void)
{
    // float temp = 20.0 + (rand() % 1500) / 100.0;  // Random temperature between 20.0 and 35.0
    // float humid = 50.0 + (rand() % 5000) / 100.0; // Random humidity between 50.0 and 100.0
	// snprintf(udpPayload, sizeof(udpPayload), "Temp: 25, Humid: 50");

	// // TODO: make this randomise work (currently got error), but when have actual sensor, don't even need it
	// // snprintf(udpPayload, sizeof(udpPayload), "Temp: %.2f, Humid: %.2f", temp, humid);
	// Random temperature between 20.0 and 35.0

	float temp = 20.0f + (rand() % 1500) / 100.0f;
 
	// Random humidity between 50.0 and 100.0
	float humid = 50.0f + (rand() % 5000) / 100.0f;

	// Print them into udpPayload as floats with 2 decimal places
	// This may trigger a "float to double promotion" warning, which is safe to ignore
	snprintf(udpPayload, sizeof(udpPayload), "Temp: %.2f, Humid: %.2f", temp, humid);
}

static otInstance *instance;
static otUdpSocket udpSocket;

LOG_MODULE_REGISTER(cli_sample, CONFIG_OT_COMMAND_LINE_INTERFACE_LOG_LEVEL);

void udpSend(otInstance *instance)
{
    otError error;
    otMessage *message;
    otMessageInfo messageInfo;

	generateRandomPayload();

    // Create a new message
    message = otUdpNewMessage(instance, NULL);
    if (message == NULL)
    {
        LOG_ERR("Failed to allocate message");
        return;
    }

    // Append the payload to the message
    error = otMessageAppend(message, udpPayload, strlen(udpPayload));
    if (error != OT_ERROR_NONE)
    {
        LOG_ERR("Failed to append message: %d", error);
        otMessageFree(message);
        return;
    }

    // Set the message info
    memset(&messageInfo, 0, sizeof(messageInfo));
    otIp6AddressFromString(UDP_DEST_ADDR, &messageInfo.mPeerAddr);
    messageInfo.mPeerPort = UDP_PORT;

	// Send the message
	error = otUdpSend(instance, &udpSocket, message, &messageInfo);
	if (error != OT_ERROR_NONE)
	{
		LOG_ERR("Failed to send UDP message: %d", error);
		otMessageFree(message);
	}
}
	
int main(void)
	{
		// Initialize OpenThread instance
		instance = otInstanceInitSingle();
		if (instance == NULL)
		{
			LOG_ERR("Failed to initialize OpenThread instance");
			return -1;
		}
	
		// Bring up the IPv6 interface
		otError error = otIp6SetEnabled(instance, true);
		if (error != OT_ERROR_NONE)
		{
			LOG_ERR("Failed to bring up IPv6 interface: %d", error);
			return -1;
		}

		// Start the Thread network
		error = otThreadSetEnabled(instance, true);
		if (error != OT_ERROR_NONE)
		{
			LOG_ERR("Failed to start Thread network: %d", error);
			return -1;
		}

		// Initialize the UDP socket
		memset(&udpSocket, 0, sizeof(udpSocket));
		otUdpOpen(instance, &udpSocket, NULL, NULL);
	
		while (1)
		{
			udpSend(instance);
			k_sleep(K_SECONDS(2)); // Send a message every 2 seconds
		}
	
		return 0;
	}

[runsiv]

Which version of NCS are you using?

You are linking to a sample for the DHT sensor which should be fine for your use. just use the binding DHT instead of DHT-22. See also https://docs.zephyrproject.org/latest/build/dts/api/bindings/sensor/aosong%2Cdht.html#dtbinding-aosong-dht 

Regards

Runar

[jonathanljc]

Hi Runar,

NCS version v2.9.0. Can you elaborate more on the binding part as I not sure what are the steps to change. Thank you.