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Derek Jamison 3f9554fb07 Add comment about GpioModeAnalog		2023-07-01 09:42:13 -05:00
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application.fam	Add Blink LED example	2023-06-11 20:37:51 -05:00
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README.md	Add comment about GpioModeAnalog	2023-07-01 09:42:13 -05:00

README.md

GPIO_BLINK

This is the classic "Hello World" of GPIO, where we blink an LED. You will need an LED (any color is fine) and a resistor (220 ohms - 1 kilohm should be fine). Connect the long side of the LED into pin A7. Connect the short size of the LED to one side of the resistor (doesn't matter which side). Connect the other side of the resistor to any of the pin GND.

Run the application and the LED should start blinking. Hold the back button to exit.

How it works

For list of pins see /firmware/targets/f7/furi_hal/furi_hal_resources.c in your firmware repo.

We define a variable for our LED...

const GpioPin* const pin_led = &gpio_ext_pa7;

We initialize the pin for output.
- GpioModeOutputPushPull means true = 3.3 volts, false = 0 volts.
- GpioModeOutputOpenDrain means true = floating, false = 0 volts.
```
furi_hal_gpio_init_simple(pin_led, GpioModeOutputOpenDrain);
```
We turn the LED on (3.3 volts on the pin).
```
furi_hal_gpio_write(pin_led, true);
```
We wait 500 ms.
```
furi_delay_ms(500);
```
We turn the LED off (0 volts on the pin).
```
furi_hal_gpio_write(pin_led, false);
```
We wait 500 ms.
```
furi_delay_ms(500);
```
We loop if the back button is not currently pressed.
```
while(furi_hal_gpio_read(pin_back))
```
Typically when a pin is no longer in use, it is set to analog mode. This causes the pin to be a floating input.
```
furi_hal_gpio_init_simple(pin_led, GpioModeAnalog);
```