pimoroni-pico/examples/breakout_encoder_wheel/gpio_pwm/gpio_pwm.cpp

74 wiersze
2.0 KiB
C++

#include <math.h>
#include <string>
#include "pimoroni_i2c.hpp"
#include "breakout_encoder_wheel.hpp"
#include "time.h"
using namespace pimoroni;
using namespace encoderwheel;
/*
Output a sine wave PWM sequence on the Encoder Wheel's side GPIO pins.
Press the centre button to stop the program.
*/
// Constants
constexpr float SPEED = 5.0f; // The speed that the LEDs will cycle at
const uint UPDATES = 50; // How many times the LEDs will be updated per second
const uint UPDATE_RATE_US = 1000000 / UPDATES;
constexpr float FREQUENCY = 1000.0f; // The frequency to run the PWM at
// Create a new BreakoutEncoderWheel
I2C i2c(BOARD::BREAKOUT_GARDEN);
BreakoutEncoderWheel wheel(&i2c);
// Variables
float offset = 0.0f;
int main() {
stdio_init_all();
// Attempt to initialise the encoder wheel
if(wheel.init()) {
// Set the PWM frequency for the GPIOs
uint16_t period = wheel.gpio_pwm_frequency(FREQUENCY);
// Set the GPIO pins to PWM outputs
for(int i = 0; i < NUM_GPIOS; i++) {
wheel.gpio_pin_mode(GPIOS[i], IOExpander::PIN_PWM);
}
// Loop forever
while(!wheel.pressed(CENTRE)) {
// Record the start time of this loop
absolute_time_t start_time = get_absolute_time();
offset += SPEED / 1000.0f;
// Update all the PWMs
for(int i = 0; i < NUM_GPIOS; i++) {
float angle = (((float)i / NUM_GPIOS) + offset) * M_PI;
uint16_t duty = (uint16_t)(((sinf(angle) / 2.0f) + 0.5f) * period);
// Set the GPIO pin to the new duty cycle, but do not load it yet
wheel.gpio_pin_value(GPIOS[i], duty, false);
}
// Have all the PWMs load at once
wheel.gpio_pwm_load();
// Sleep until the next update, accounting for how long the above operations took to perform
sleep_until(delayed_by_us(start_time, UPDATE_RATE_US));
}
// Turn off the PWM outputs
for(int i = 0; i < NUM_GPIOS; i++) {
wheel.gpio_pin_value(GPIOS[i], 0);
}
}
return 0;
}