Difference between revisions of "Matrix - LED"

Latest revision as of 14:36, 21 June 2016

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1 Introduction

LED

LED

LED

The Matrix-LED is an LED module with three 2.54 mm spacing pins: V(supply voltage),G(ground) and S(signal) which is connected to a triode to turn the LED on or off. You can write high or low, or PWN signals(3.3V or 5V) to S. When you write high to S the LED will turn on and become brightest. When you write low to S the LED will turn off. If you write PWM signals to S the LED's brightness will vary depending on the PWM's signal variances.

2 Features

• GPIO/PWM interface, 3.3/5V, PWM brightness control
• Small, easy to be used in various situations
• 2.54 mm spacing pin
• PCB Dimension(mm): 8 x 24

• Pin Description:

3 Basic Device Operation

The module has three 2.54 mm spacing pins: V(supply voltage),G(ground) and S(signal) which is connected to a triode to turn the LED on or off. You can write high or low, or PWN signals(3.3V or 5V) to S. When you write high to S the LED will turn on and become brightest. When you write low to S the LED will turn off. If you write PWM signals to S the LED's brightness will vary depending on the PWM's signal variances.

4 Applications

4.1 Connect to NanoPi M1

Refer to the following connection diagram to connect the module to the NanoPi M1:

Connection Details:

4.2 Connect to NanoPi 2

Refer to the following connection diagram to connect the module to the NanoPi 2:

Connection Details:

4.3 Connect to NanoPi M2 / NanoPi 2 Fire

Refer to the following connection diagram to connect the module to the NanoPi M2/ NanoPi 2 Fire:

Connection Details:

4.4 Connect to NanoPC-T2

Refer to the following connection diagram to connect the module to the NanoPC-T2:
Matrix-LED_NanoPC-T2

Connection Details:

5 Compile & Run Test Program

Boot your ARM board with Debian and copy the matrix code:

$ apt-get update && apt-get install git
$ git clone https://github.com/friendlyarm/matrix.git

If your cloning is done successfully a "matrix" directory will be generated.

Compile and install Matrix:

$ cd matrix
$ make && make install

Run test program:

$ matrix-gpio_out

Note: this module is not plug and play therefore before running the module please make sure it is connected to an ARM board.
Here is what you should observe:

1: gpio status change
2: gpio status change
3: gpio status change
4: gpio status change
5: gpio status change

The LED will be blinking continuously.

6 Code Sample

This Matrix code sample can work with all the ARM boards mentioned in this module's wiki. The name of this code sample is "matrix-gpio_out". Here is its source code:

int main(int argc, char ** argv) 
{
    int pin = GPIO_PIN(7); 
    int i, value, board;
    int ret = -1;
 
    if ((board = boardInit()) < 0) {
        printf("Fail to init board\n");
        return -1;
    }
    if (board == BOARD_NANOPI_T2)
        pin = GPIO_PIN(15);
 
    if (argc == 2)
        pin = GPIO_PIN(atoi(argv[1]));
    if ((ret = exportGPIOPin(pin)) == -1) {   
        printf("exportGPIOPin(%d) failed\n", pin);
    }
    if ((ret = setGPIODirection(pin, GPIO_OUT)) == -1) {
        printf("setGPIODirection(%d) failed\n", pin);
    }
    for (i = 0; i < STATUS_CHANGE_TIMES; i++) {
        if (i % 2) {
            value = GPIO_HIGH;
        } else {
            value = GPIO_LOW;
        }
        if ((ret = setGPIOValue(pin, value)) > 0) {
            printf("%d: GPIO_PIN(%d) value is %d\n", i+1, pin, value);
        } else {
            printf("setGPIOValue(%d) failed\n", pin);
        }
        sleep(1);
    }
    unexportGPIOPin(pin);
    return 0;
}

For more details about this APIs called in this code sample refer to Matrix API reference manual

7 Resources

8 Update Log

8.1 Feb-18-2016

• Added the description for "NanoPi 2 branch" in Section 4
• Added Section 5: Connect to NanoPi 2

8.2 June-21-2016

• Re-organized and simplified wiki