.. | ||
application.fam | ||
gpio_interrupt_demo_app.c | ||
gpio_interrupt_demo.png | ||
README.md |
BASIC DEMO
Introduction
This is a basic demo of using GPIO interrupts.
Installation Directions
This project is intended to be overlayed on top of an existing firmware repo.
- Clone, Build & Deploy an existing flipper zero firmware repo. See this tutorial for updating firmware.
- Copy the "gpio_interrupt_demo" folder to the \applications\plugins\gpio_interrupt_demo folder in your firmware.
- Build & deploy the firmware. See this tutorial for updating firmware.
- NOTE: You can also extract the gpio_interrupt_demo.FAP from resources.tar file and use qFlipper to copy the file to the SD Card/apps/Misc folder.
Connecting the hardware
GPIO pin C3 is our interrupt pin (with internal pull-up resistor). I connect pin to a 220 ohm resistor and then the other side of the resistor to one side of a momentary switch. Other side of the switch connects to our GND pin.
GPIO A7, A6 and A4 connect to 220ohm resistors then the + or - pins of LED... LED1: +A7 -A6 LED2: +A6 -A7 LED3: +A7 -A4 LED4: +A4 -A7 LED5: +A6 -A4 LED6: +A4 -A6
Running the updated firmware
These directions assume you are starting at the flipper desktop. If not, please press the back button until you are at the desktop.
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Press the OK button on the flipper to pull up the main menu.
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Choose "Applications" from the menu.
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Choose "GPIO" from the sub-menu.
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Choose "GPIO Interrupt Demo"
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Message "GND pin C3 to stop." should display
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LEDs should blink in order.
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press switch (or connect wire/resistor between C3 and GND)
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LEDs should stop and display should say "Stopped on LED 4." (or whatever LED was lit.)
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Press DOWN button on Flipper Zero to start over.
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Press the BACK button to exit.
How it works
-
application.fam
- See basic demo for explanation.
-
basic_demo.png
- See basic demo for explanation.
-
basic_demo_app.c
- GPIO specific code:
- furi_hal_gpio_init(&gpio_ext_pc3, GpioModeInterruptFall, GpioPullUp, GpioSpeedVeryHigh);
- gpio_ext_pc3 is the GPIO pin we are using for interrupt input.
- GpioModeInterruptFall - means trigger callback on falling edge (VCC->GND)
- GpioModeInterruptRise - means trigger callback on rising edge (GND->VCC)
- GpioModeInterruptRiseFall - means trigger callback on either edge
- GpioPullUp - Means enable internal pull-up resistor between VCC and pin.
- GpioPullDown - Means enable internal pull-down resistor between GND and pin.
- GpioPullNo - Means do not enable internal pull-up/pull-down resistor.
- GpioSpeedVeryHigh - priority of input?
- furi_hal_gpio_add_int_callback(&gpio_ext_pc3, demo_gpio_fall_callback, NULL);
- gpio_ext_pc3 is the GPIO pin we are using for interrupt input.
- second parameter is callback with signature: "void fnName(void* ctx)"
- third parameter is object to pass into callback for context (or NULL if no object).
- once furi_hal_gpio_add_int_callback is invoked, the callback is enabled.
- demo_gpio_fall_callback(void* ctx)
- this method gets invoked by our callback (because of previous add_int_callback) wheneven pin C3 gets pulled to GND.
- interrupt callbacks should try to do mininal amount of processing.
- furi_hal_gpio_remove_int_callback(&gpio_ext_pc3);
- removes the callback, so method is no longer invoked on pin transistion.
- furi_hal_gpio_init(&gpio_ext_pc3, GpioModeInterruptFall, GpioPullUp, GpioSpeedVeryHigh);
- GPIO specific code: