Exposed support for GPIO pins on encoder wheel

Author: ZodiusInfuser

drivers/ioexpander/ioexpander.cpp

@@ -523,13 +523,35 @@ namespace pimoroni {
     return divider_good;
   }
 
-  void IOExpander::set_pwm_period(uint16_t value, bool load) {
+  void IOExpander::set_pwm_period(uint16_t value, bool load, bool wait_for_load) {
     value &= 0xffff;
     i2c->reg_write_uint8(address, reg::PWMPL, (uint8_t)(value & 0xff));
     i2c->reg_write_uint8(address, reg::PWMPH, (uint8_t)(value >> 8));
 
     if(load)
-      pwm_load();
+      pwm_load(wait_for_load);
+  }
+
+  uint16_t IOExpander::set_pwm_frequency(float frequency, bool load, bool wait_for_load) {
+    uint32_t period = (uint32_t)(CLOCK_FREQ / frequency);
+    if (period / 128 > MAX_PERIOD) {
+      return MAX_PERIOD;
+    }
+    if (period < 2) {
+      return 2;
+    }
+
+    uint8_t divider = 1;
+    while ((period > MAX_PERIOD) && (divider < MAX_DIVIDER)) {
+      period >>= 1;
+      divider <<= 1;
+    }
+
+    period = MIN(period, MAX_PERIOD); // Should be unnecessary because of earlier raised errors, but kept in case
+    set_pwm_control(divider);
+    set_pwm_period((uint16_t)(period - 1), load, wait_for_load);
+
+    return (uint16_t)period;
   }
 
   uint8_t IOExpander::get_mode(uint8_t pin) {
@@ -701,7 +723,7 @@ namespace pimoroni {
     }
   }
 
-  void IOExpander::output(uint8_t pin, uint16_t value, bool load) {
+  void IOExpander::output(uint8_t pin, uint16_t value, bool load, bool wait_for_load) {
     if(pin < 1 || pin > NUM_PINS) {
       printf("Pin should be in range 1-14.");
       return;
@@ -717,7 +739,7 @@ namespace pimoroni {
       i2c->reg_write_uint8(address, io_pin.reg_pwml, (uint8_t)(value & 0xff));
       i2c->reg_write_uint8(address, io_pin.reg_pwmh, (uint8_t)(value >> 8));
       if(load)
-        pwm_load();
+        pwm_load(wait_for_load);
     }
     else {
       if(value == LOW) {

drivers/ioexpander/ioexpander.hpp

@@ -27,6 +27,9 @@ namespace pimoroni {
     static const uint8_t PIN_MODE_ADC = 0b01010;  // ADC, Input-only (high-impedance)
 
     static const uint32_t RESET_TIMEOUT_MS = 1000;
+    static const uint32_t CLOCK_FREQ = 24000000;
+    static const uint32_t MAX_PERIOD = (1 << 16) - 1;
+    static const uint32_t MAX_DIVIDER = (1 << 7);
 
   public:
     static const uint8_t DEFAULT_I2C_ADDRESS = 0x18;
@@ -205,15 +208,16 @@ namespace pimoroni {
     void pwm_clear(bool wait_for_clear = true);
     bool pwm_clearing();
     bool set_pwm_control(uint8_t divider);
-    void set_pwm_period(uint16_t value, bool load = true);
+    void set_pwm_period(uint16_t value, bool load = true, bool wait_for_load = true);
+    uint16_t set_pwm_frequency(float frequency, bool load = true, bool wait_for_load = true);
 
     uint8_t get_mode(uint8_t pin);
     void set_mode(uint8_t pin, uint8_t mode, bool schmitt_trigger = false, bool invert = false);
 
     int16_t input(uint8_t pin, uint32_t adc_timeout = 1);
     float input_as_voltage(uint8_t pin, uint32_t adc_timeout = 1);
 
-    void output(uint8_t pin, uint16_t value, bool load = true);
+    void output(uint8_t pin, uint16_t value, bool load = true, bool wait_for_load = true);
 
     void setup_rotary_encoder(uint8_t channel, uint8_t pin_a, uint8_t pin_b, uint8_t pin_c = 0, bool count_microsteps = false);
     int16_t read_rotary_encoder(uint8_t channel);

examples/breakout_encoder_wheel/CMakeLists.txt

@@ -3,6 +3,6 @@ add_subdirectory(chase_game)
 add_subdirectory(clock)
 add_subdirectory(colour_picker)
 add_subdirectory(encoder)
-#add_subdirectory(gpio_pwm)
+add_subdirectory(gpio_pwm)
 add_subdirectory(led_rainbow)
 add_subdirectory(stop_watch)

examples/breakout_encoder_wheel/gpio_pwm/CMakeLists.txt

@@ -0,0 +1,13 @@
+set(OUTPUT_NAME encoderwheel_gpio_pwm)
+add_executable(${OUTPUT_NAME} gpio_pwm.cpp)
+
+# Pull in pico libraries that we need
+target_link_libraries(${OUTPUT_NAME}
+  pico_stdlib
+  breakout_encoder_wheel
+)
+
+# enable usb output
+pico_enable_stdio_usb(${OUTPUT_NAME} 1)
+
+pico_add_extra_outputs(${OUTPUT_NAME})

examples/breakout_encoder_wheel/gpio_pwm/gpio_pwm.cpp

@@ -0,0 +1,74 @@
+#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;
+}

libraries/breakout_encoder_wheel/breakout_encoder_wheel.cpp

@@ -190,32 +190,37 @@ namespace encoderwheel {
     led_ring.update();
   }
 
-  int BreakoutEncoderWheel::gpio_pin_mode(int gpio) {
-    return 0; // TODO
+  uint8_t BreakoutEncoderWheel::gpio_pin_mode(uint8_t gpio) {
+    assert(gpio < GP7 || gpio > GP9);
+    return ioe.get_mode(gpio);
   }
 
-  void BreakoutEncoderWheel::gpio_pin_mode(int gpio, int mode) {
-
+  void BreakoutEncoderWheel::gpio_pin_mode(uint8_t gpio, uint8_t mode) {
+    assert(gpio < GP7 || gpio > GP9);
+    ioe.set_mode(gpio, mode);
   }
 
-  int BreakoutEncoderWheel::gpio_pin_value(int gpio) {
-    return 0; // TODO
+  int16_t BreakoutEncoderWheel::gpio_pin_value(uint8_t gpio) {
+    assert(gpio < GP7 || gpio > GP9);
+    return ioe.input(gpio);
   }
 
-  float BreakoutEncoderWheel::gpio_pin_value_as_voltage(int gpio) {
-    return 0; // TODO
+  float BreakoutEncoderWheel::gpio_pin_value_as_voltage(uint8_t gpio) {
+    assert(gpio < GP7 || gpio > GP9);
+    return ioe.input_as_voltage(gpio);
   }
 
-  void BreakoutEncoderWheel::gpio_pin_value(int gpio, int value, bool load, bool wait_for_load) {
-
+  void BreakoutEncoderWheel::gpio_pin_value(uint8_t gpio, uint16_t value, bool load, bool wait_for_load) {
+    assert(gpio < GP7 || gpio > GP9);
+    ioe.output(gpio, value, load, wait_for_load);
   }
 
   void BreakoutEncoderWheel::gpio_pwm_load(bool wait_for_load) {
-
+    ioe.pwm_load(wait_for_load);
   }
 
   int BreakoutEncoderWheel::gpio_pwm_frequency(float frequency, bool load, bool wait_for_load) {
-    return 0; // TODO
+    return ioe.set_pwm_frequency(frequency, load, wait_for_load);
   }
 
   void BreakoutEncoderWheel::take_encoder_reading() {

libraries/breakout_encoder_wheel/breakout_encoder_wheel.hpp

@@ -41,17 +41,17 @@ namespace encoderwheel {
     static const uint32_t DEFAULT_TIMEOUT     = 1;
 
   private:
-    static const uint8_t ENC_CHANNEL    = 1;
-    static const uint8_t ENC_TERM_A     = 3;
-    static const uint8_t ENC_TERM_B     = 12;
-    static const uint8_t ENC_COUNTS_PER_REV = 24;
-    static const uint8_t ENC_COUNT_DIVIDER = 2;
-
-    static const uint8_t SW_UP          = 13;
-    static const uint8_t SW_DOWN        = 4;
-    static const uint8_t SW_LEFT        = 11;
-    static const uint8_t SW_RIGHT       = 2;
-    static const uint8_t SW_CENTRE      = 1;
+    static const uint8_t ENC_CHANNEL          = 1;
+    static const uint8_t ENC_TERM_A           = 3;
+    static const uint8_t ENC_TERM_B           = 12;
+    static const uint8_t ENC_COUNTS_PER_REV   = 24;
+    static const uint8_t ENC_COUNT_DIVIDER    = 2;
+
+    static const uint8_t SW_UP                = 13;
+    static const uint8_t SW_DOWN              = 4;
+    static const uint8_t SW_LEFT              = 11;
+    static const uint8_t SW_RIGHT             = 2;
+    static const uint8_t SW_CENTRE            = 1;
 
     // This wonderful lookup table maps the LEDs on the encoder wheel
     // from their 3x24 (remember, they're RGB) configuration to
@@ -146,12 +146,12 @@ namespace encoderwheel {
     void clear();
     void show();
 
-    int gpio_pin_mode(int gpio);
-    void gpio_pin_mode(int gpio, int mode);
-    int gpio_pin_value(int gpio);
-    float gpio_pin_value_as_voltage(int gpio);
-    void gpio_pin_value(int gpio, int value, bool load = true, bool wait_for_load = false);
-    void gpio_pwm_load(bool wait_for_load = false);
+    uint8_t gpio_pin_mode(uint8_t gpio);
+    void gpio_pin_mode(uint8_t gpio, uint8_t mode);
+    int16_t gpio_pin_value(uint8_t gpio);
+    float gpio_pin_value_as_voltage(uint8_t gpio);
+    void gpio_pin_value(uint8_t gpio, uint16_t value, bool load = true, bool wait_for_load = false);
+    void gpio_pwm_load(bool wait_for_load = true);
     int gpio_pwm_frequency(float frequency, bool load = true, bool wait_for_load = false);
 
   private: