Difference between revisions of "Matrix - Temperature and Humidity Sensor"
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Revision as of 09:22, 28 December 2015
Contents
Introduction
- The Matrix-Temperature_and_Humidity_Sensor module is used to detect temperature and humidity.
- It utilizes the DHT11 temperature and humidity sensor. Its humidity range is 20% - 80% and the accuracy is 5%. Its temperature range is 0℃ - 50℃ and the accuracy is ±2℃.
Features
- Humidity range: 20 - 80%RH, Temperature range 0 ~ 50℃
- Accuracy of humidity: +-5%RH, accuracy of temperature: +-2℃
- One wire communication
- 2.54 mm spacing pin
- PCB dimension (mm): 16 x 32
Pin Description:
Pin | Description |
S | GPIO |
V | Supply Voltage 5V |
G | Ground |
Basic Device Operation
The DHT11 module uses a simplified single-bus serial communication. DATA controls communication and synchronization between the microprocessor and DHT11. A data transfer takes 4ms. The data format contains an integer part and a decimal part. The basic operation is as follows:
- a transmission of 40 data, the high first-out
- data format: 8bit humidity integer data + 8bit the Humidity decimal data
- 8bit temperature integer data + 8bit fractional temperature data
- 8 bit parity bit
- If a transmission is successful the “8bit humidity integer data + 8bit humidity decimal data +8 bit temperature integer data + 8bit temperature fractional data” 8bit checksum is equal to the results of the last eight.
- After the user host (MCU) sends a signal DHT11 is converted from low-power mode to high-speed mode, until the host begins to signal the end. Then DHT11 sends a response signal to send 40bit data, and trigger a letter collection. If DHT11 doesn't receive a signal from the host it will not begin a letter collection. After the letter collection is done DHT11 will turn to low power mode.
Download Matrix Source Code
All the matrix modules' code samples are open source. They are maintained on GitHub - https://github.com/friendlyarm/matrix.git
Each branch in this hub contains the matrix modules' code samples for a board that the matrix modules can work with.
- The nanopi branch contains the matrix modules' code samples for the NanoPi
- The tiny4412 branch contains the matrix modules' code samples for the Tiny4412
- The raspberrypi branch contains the matrix modules' code samples for the RaspberryPi
Please follow the steps below to get the source code:
Install the git utility on a PC running Ubuntu14.04
$ sudo apt-get install git
Clone the matrix code from GitHub
$ git clone https://github.com/friendlyarm/matrix.git
If this is successful a "matrix" directory will be generated, which will contain all the matrix modules' code samples.
Connect to NanoPi
Preparations
Please install a Debian on a NanoPi and an appropriate cross compiler on a PC. Please refer to wiki:NanoPi
Compile a NanoPi kernel. Note: please use the kernel's source code from the nanopi-v4.1.y-matrix branch.
$ git clone https://github.com/friendlyarm/linux-4.x.y.git
$ cd linux-4.x.y
$ git checkout nanopi-v4.1.y-matrix
$ make nanopi_defconfig
$ touch .scmversion
$ make
Hardware Connection
Please refer to the following connection diagram to connect the Matrix-Temperature_and_Humidity_Sensor to the NanoPi
Connection Details:
Matrix-Temperature_and_Humidity_Sensor | NanoPi |
S | Pin7 |
V | Pin4 |
G | Pin6 |
Compile Test Program
Please login the matrix hub and enter the nanopi branch
$ cd matrix
$ git checkout nanopi
Compile the matrix code
$ make CROSS_COMPILE=arm-linux- clean
$ make CROSS_COMPILE=arm-linux-
$ make CROSS_COMPILE=arm-linux- install
Note: please make sure to install the cross compiler "arm-linux-gcc-4.4.3" on your PC, which is used to compile files for the NanoPi-Debian.
Generated library files are under the "install/lib" directory. Applications are under the "install/usr/bin" directory. The test program for the "Matrix-Temperature_and_Humidity_Sensor" module is "matrix-temp_humidity".
Run Test Program
Please copy the library files and test program to the NanoPi
$ cp install/usr/usr/bin/* nanopi_rootfs/usr/usr/bin/
$ cp install/lib/* nanopi_rootfs/lib/ -d
Power on the NanoPi and run the following command in Debian's terminal
Note: this module is not plug and play therefore before running the module please make sure it is connected to a NanoPi.
$ matrix-temp_humidity
Code Sample
int main(int argc, char ** argv)
{
int ret = -1;
int dhtTemp = 0;
int dhtHdty = 0;
int devFD = -1;
int pin = GPIO_PIN1;
if (argc == 2) {
parseCmd(argc, argv, &pin);
} else {
printf("Using default pin GPIO_PIN1\n");
}
if ((devFD = dht11Init(pin)) == -1) {
printf("Fail to init dht11\n");
return -1;
}
if ((ret = dht11Read(DHT_HUMIDITY, &dhtHdty)) != -1) {
printf("Get humidity : %d\n", dhtHdty);
} else {
printf("Faided to get humidity\n");
}
if ((ret = dht11Read(DHT_TEMP, &dhtTemp)) != -1) {
printf("Get temperature : %d\n", dhtTemp);
} else {
printf("Faided to get temperature\n");
}
dht11DeInit(devFD);
return ret;
}
Connect to Tiny4412
Preparations
Please refer to the Tiny4412's user's manual to install a UbuntuCore on the Tiny4412 and install an appropriate cross compiler on a PC.
Note: only the Tiny4412SDK-1506 carrier board can work with this module.
Hardware Connection
Please refer to the following diagram to connect the Matrix-Temperature_and_Humidity_Sensor to the Tiny4412
Connection Details:
Matrix-Temperature_and_Humidity_Sensor | Tiny4412 |
S | GPIO1 S |
V | GPIO1 5V |
G | GPIO1 GND |
Compile Test Program
Please login the Matrix hub and enter the matrix-tiny4412 branch
$ cd matrix
$ git checkout tiny4412
Compile the matrix code
$ make CROSS_COMPILE=arm-linux-gnueabihf- clean
$ make CROSS_COMPILE=arm-linux-gnueabihf-
$ make CROSS_COMPILE=arm-linux-gnueabihf- install
Note: please make sure to install the cross compiler "arm-linux-gnueabihf-gcc-4.7.3" on your PC, which is used to compile files for the Tiny4412-UbuntuCore.
Generated library files are under the "install/lib" directory. Applications are under the "install/usr/bin" directory. The test program for the "Matrix-Temperature_and_Humidity_Sensor" module is "matrix-temp_humidity".
Run Test Program
Please copy the library files and test program to the Tiny4412
$ cp install/usr/usr/bin/* tiny4412_rootfs/usr/usr/bin/
$ cp install/lib/* tiny4412_rootfs/lib/ -d
Power on the Tiny4412 and run the following command in UbuntuCore's terminal
Note: this module is not plug and play therefore before running the module please make sure it is connected to a Tiny4412.
$ matrix-temp_humidity
Code Sample
int main(int argc, char ** argv)
{
int ret = -1;
int dhtTemp = 0;
int dhtHdty = 0;
int devFD = -1;
int pin = GPIO_PIN1;
if (argc == 2) {
parseCmd(argc, argv, &pin);
} else {
printf("Using default pin GPIO_PIN1\n");
}
if ((devFD = dht11Init(pin)) == -1) {
printf("Fail to init dht11\n");
return -1;
}
if ((ret = dht11Read(DHT_HUMIDITY, &dhtHdty)) != -1) {
printf("Get humidity : %d\n", dhtHdty);
} else {
printf("Faided to get humidity\n");
}
if ((ret = dht11Read(DHT_TEMP, &dhtTemp)) != -1) {
printf("Get temperature : %d\n", dhtTemp);
} else {
printf("Faided to get temperature\n");
}
dht11DeInit(devFD);
return ret;
}
Connect to RaspberryPi
Connect to Arduino
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