MaixCAM MaixPy Using GPIO

2024-11-20

Introduction

Using GPIO allows you to control pins for input or output high and low levels, which is commonly used to read signals or output control signals.

Note: The pins on the MaixCAM are tolerant to 3.3V. Do not input 5V voltage.

Using GPIO in MaixPy

MaixPy Firmware should > 4.1.2(not include)

First, we need to know which pins and GPIOs the device has. For MaixCAM, each pin corresponds to a GPIO controller, as shown in the figure:

maixcam_pro_io

It is important to note that pins can be used not only as GPIOs but also for other functions like PWM. Before using them, we need to set the pin function to GPIO.

For example, on MaixCAM, some pins are already occupied by other functions by default, such as UART0 and WiFi (SDIO1 + A26), so it is not recommended to use them.

Other pins can be used, and the A14 pin is connected to the onboard LED, which is used as a system load indicator by default. If initialized, it will automatically disable the system indicator function and can be used as a regular GPIO (note that A14 can only be used as an output). This way, you can control the LED's on and off state.

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The circuit diagram of the LED is shown in the figure. Therefore, we only need to provide a high signal to pin A14, and the LED will conduct and light up:

from maix import gpio, pinmap, time

pinmap.set_pin_function("A14", "GPIOA14")
led = gpio.GPIO("GPIOA14", gpio.Mode.OUT)
led.value(0)

while 1:
    led.toggle()
    time.sleep_ms(500)

Here, we first use pinmap to set the function of the A14 pin to GPIO. Of course, for A14, since it only has the GPIO function, it can be omitted. For the sake of generality, other pins may need to be set, so it is set in this example.

For more APIs, please refer to the GPIO API Documentation

GPIO in Input Mode

from maix import gpio, pinmap, time

pinmap.set_pin_function("A19", "GPIOA19")
led = gpio.GPIO("GPIOA19", gpio.Mode.IN)

while 1:
    print(led.value())
    time.sleep_ms(1) # sleep to make cpu free

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MaixCAM-Pro Uses Illumination LED

Both MaixCAM and MaixCAM-Pro have a small LED light connected to pin A14. Additionally, the MaixCAM-Pro has an onboard illumination LED connected to pin B3, which is turned on by a high signal and off by a low signal:

from maix import gpio, pinmap, time

pinmap.set_pin_function("B3", "GPIOB3")
led = gpio.GPIO("GPIOB3", gpio.Mode.OUT)
led.value(0)

while 1:
    led.toggle()
    time.sleep_ms(500)

PINMAP

UART