Difference between revisions of "Matrix - Thermistor"
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Revision as of 22:00, 5 February 2016
Contents
Introduction
- The Matrix-Thermistor module is a thermistor module. It has a 3 pin 2.54mm spacing pin header of which V is supply voltage, G is ground and S is output analog signal. Users can convert output analog signals to digital signals via ADC conversion.
- To increase measured values' accuracy please make the sensor in close contact with a measured object.
Features
- GPIO, 3.3/5V
- Small
- 2.54mm spacing pin header
- PCB Dimension(mm): 8 x 24
- Pin Description:
Pin | Description |
S | Analog GPIO |
V | Supply Voltage 5V |
G | Ground |
Basic Device Operation
- The module mainly contains a thermistor. A thermistor is a type of resistor whose resistance is dependent on temperature.
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 matrix-nanopi branch contains the matrix modules' code samples for the NanoPi;
- The matrix-nanopi2 branch contains the matrix modules' code samples for the NanoPi 2;
- The matrix-tiny4412 branch contains the matrix modules' code samples for the Tiny4412;
- The matrix-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 2
Hardware Connection
Please refer to the following connection diagram to connect the Matrix-Thermistor to the NanoPi 2:
Connection Details:
Matrix-Analog_to_Digital_Converter | NanoPi 2 |
SDA | Pin3 |
SCL | Pin5 |
5V | Pin4 |
GND | Pin6 |
Matrix-Thermistor | |
GND | NanoPi 2 Pin9 |
5V | NanoPi 2 Pin2 |
S | Matrix-Analog_to_Digital_Converter A0 |
This module's output signals are analog signals. You can use our Matrix-Analog_to_Digital_Converter to convert them to digital signals.
Please connect the Matrix-Analog_to_Digital_Converter to the NanoPi 2 and then connect Pin S of the Matrix-Thermistor's pin header to Matrix-Analog_to_Digital_Converter's A0.
For more details about the Matrix-Analog_to_Digital_Converter module please refer to wiki:Matrix_-_Analog_to_Digital_Converter.
Compile Test Program
Please login the matrix hub and enter the nanopi2 branch
$ cd matrix
$ git checkout nanopi2
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-4.9.3" on your PC, which is used to compile files for the NanoPi 2.
Generated library files are under the "install/lib" directory. The test program is under the "install/usr/bin" directory. Its test program is "matrix-adc".
The modules are under the "modules" directory. Its driver's source code is in https://github.com/friendlyarm/linux-3.4.y.git.
Run Test Program
Please insert a TF card which is flashed with Debian to a Linux host and mount its boot and rootfs sections.
We assume the rootfs is mounted to /media/rootfs then please run the following commands to copy the driver, library and test program to the card.
$ cp modules /media/rootfs/ -r
$ cp install/lib/* /media/rootfs/lib/ -d
$ cp install/usr/bin/* /media/rootfs/usr/bin/
Insert this TF card to your NanoPi 2, power on and run the following commands to load the driver.
$ cd /modules
$ insmod pcf8591.ko
Please run the following command to test the Matrix-Thermistor module.
$ matrix-adc
Here is what you should expect:
Code Sample
int main(int argc, char ** argv)
{
int i = 0;
int value = 0;
int channel = 0;
if (argc == 2) {
channel = atoi(argv[1]);
}
for (i=0; i<ADC_READ_TIMES; i++) {
if (pcf8591Read(channel, &value) != -1) {
printf("channel%d value=%d\n", channel, value);
} else {
printf("Fail to get channel%d value\n", channel);
}
usleep(10000);
}
return 0;
}