GPIO Interface

Note

GPIOs can be used to drive a physical pin on the microcontroller to 3.3V or GND in order to control for example an LED. Alternatively they can also read if there’s currently 3.3V or GND being applied to the pin, to detect for example the state of a button.

Configuration

It’s possible to change input / output configuration of a GPIO pin using libyggdrasil.

CC++

yggdrasil_GPIO_MakeOutput(LedBlue);
yggdrasil_GPIO_MakeInput(ButtonA);

Simple Usage

The following code will cause the blue User LED to light up, the yellow LED to turn off and the red LED to blink.

CC++

yggdrasil_GPIO_Set(LedBlue, true);
yggdrasil_GPIO_Set(LedYellow, false);
yggdrasil_GPIO_Toggle(LedRed);

It’s also possible to read and write multiple pins at once. For this use the following:

CC++

yggdrasil_GPIO_SetMultiple(GPIOA, 0, 3, 0x0A);
u8 bits = yggdrasil_GPIO_GetMultiple(GPIOA, 4, 7);

This code turns Pin 1 and 3 of Port A on and Pin 0 and 2 off. Then it reads the values of pin 4 to 7 and stores the value into a variable.

Available Pins

Name	Aliases	Description
LD1	LDA, LedBlue	LED 1, Blue
LD2	LDB, LedRed	LED 2, Red
LD3	LDC, LedYellow	LED 3, Yellow
LD4	LDD, LedGreen	LED 4, Green
EncoderButton		Encoder Push Button
DriverA	LD5, LDE	Driver Pin A, Green LED
DriverB	LD6, LDF	Driver Pin B, Green LED
DriverC	LD7, LDG	Driver Pin C, Green LED
DriverD	LD8, LDH	Driver Pin D, Green LED
EnableRGB		Enable RGB LED Matrix
SPIACE		SPIA Chip Enable
TC78Mode		Motor Driver Mode Select
TC78Err		Motor Driver Error
TC78Stby		Motor Driver Standby
PhaseA		Motor CH A Direction
PhaseB		Motor CH B Direction

Custom Pin

In order to control a pin that has not been pre-defined by libyggdrasil, first it needs to be properly configured through the project’s .ioc file. Once this is done, the new pin, in this case the Port E Pin 7, can be defined like this:

CC++

gpio_t MyPin = { GPIOE, 7 };

and then used like all other GPIO Pins.

CC++

if (yggdrasil_GPIO_Get(MyPin))
    LedGreen = true;