70 lines
3.4 KiB
Markdown
70 lines
3.4 KiB
Markdown
# BASIC DEMO
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## Introduction
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This is a basic demo of using GPIO interrupts.
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## Installation Directions
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This project is intended to be overlayed on top of an existing firmware repo.
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- Clone, Build & Deploy an existing flipper zero firmware repo. See this [tutorial](/firmware/updating/README.md) for updating firmware.
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- Copy the "gpio_interrupt_demo" [folder](..) to the \applications\plugins\gpio_interrupt_demo folder in your firmware.
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- Build & deploy the firmware. See this [tutorial](/firmware/updating/README.md) for updating firmware.
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- 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.
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## Connecting the hardware
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GPIO pin C3 is our interrupt pin (with internal pull-up resistor). I connect pin
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to a 220 ohm resistor and then the other side of the resistor to one side of a
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momentary switch. Other side of the switch connects to our GND pin.
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GPIO A7, A6 and A4 connect to 220ohm resistors then the + or - pins of LED...
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LED1: +A7 -A6
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LED2: +A6 -A7
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LED3: +A7 -A4
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LED4: +A4 -A7
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LED5: +A6 -A4
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LED6: +A4 -A6
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## Running the updated firmware
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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.
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## How it works
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- application.fam
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- See [basic demo](../../plugins/basic/README.md) for explanation.
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- basic_demo.png
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- See [basic demo](../../plugins/basic/README.md) for explanation.
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- basic_demo_app.c
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- GPIO specific code:
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- furi_hal_gpio_init(&gpio_ext_pc3, GpioModeInterruptFall, GpioPullUp, GpioSpeedVeryHigh);
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- gpio_ext_pc3 is the GPIO pin we are using for interrupt input.
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- GpioModeInterruptFall - means trigger callback on falling edge (VCC->GND)
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- GpioModeInterruptRise - means trigger callback on rising edge (GND->VCC)
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- GpioModeInterruptRiseFall - means trigger callback on either edge
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- GpioPullUp - Means enable internal pull-up resistor between VCC and pin.
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- GpioPullDown - Means enable internal pull-down resistor between GND and pin.
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- GpioPullNo - Means do not enable internal pull-up/pull-down resistor.
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- GpioSpeedVeryHigh - priority of input?
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- furi_hal_gpio_add_int_callback(&gpio_ext_pc3, demo_gpio_fall_callback, NULL);
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- gpio_ext_pc3 is the GPIO pin we are using for interrupt input.
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- second parameter is callback with signature: "void fnName(void* ctx)"
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- third parameter is object to pass into callback for context (or NULL if no object).
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- once furi_hal_gpio_add_int_callback is invoked, the callback is enabled.
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- demo_gpio_fall_callback(void* ctx)
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- this method gets invoked by our callback (because of previous add_int_callback) wheneven pin C3 gets pulled to GND.
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- interrupt callbacks should try to do mininal amount of processing.
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- furi_hal_gpio_remove_int_callback(&gpio_ext_pc3);
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- removes the callback, so method is no longer invoked on pin transistion.
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