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RIOT/drivers/apa102/apa102.c 1.89 KB
a752c7ab   elopes   add first test an...
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  /*
   * Copyright (C) 2017 Freie Universitรคt Berlin
   *
   * This file is subject to the terms and conditions of the GNU Lesser
   * General Public License v2.1. See the file LICENSE in the top level
   * directory for more details.
   */
  
  /**
   * @ingroup     drivers_apa102
   * @{
   *
   * @file
   * @brief       APA 102 RGB LED driver implementation
   *
   * @author      Hauke Petersen <hauke.petersen@fu-berlin.de>
   *
   * @}
   */
  
  #include <string.h>
  
  #include "assert.h"
  #include "apa102.h"
  
  #define START           (0x00000000)
  #define END             (0xffffffff)
  
  #define HEAD            (0xe0000000)
  #define BRIGHT          (0x1f000000)
  #define BLUE            (0x00ff0000)
  #define GREEN           (0x0000ff00)
  #define RED             (0x000000ff)
  #define BRIGHT_SHIFT    (21U)
  #define BLUE_SHIFT      (16U)
  #define GREEN_SHIFT     (8U)
  
  
  static inline void shift(const apa102_t *dev, uint32_t data)
  {
      for (int i = 31; i >= 0; i--) {
          gpio_write(dev->data_pin, ((data >> i) & 0x01));
          gpio_set(dev->clk_pin);
          gpio_clear(dev->clk_pin);
      }
  }
  
  void apa102_init(apa102_t *dev, const apa102_params_t *params)
  {
      assert(dev && params);
  
      memcpy(dev, params, sizeof(apa102_params_t));
  
      gpio_init(dev->data_pin, GPIO_OUT);
      gpio_init(dev->clk_pin, GPIO_OUT);
      gpio_clear(dev->data_pin);
      gpio_clear(dev->clk_pin);
  }
  
  void apa102_load_rgba(const apa102_t *dev, const color_rgba_t vals[])
  {
      assert(dev && vals);
  
      shift(dev, START);
      for (int i = 0; i < dev->led_numof; i++) {
          uint32_t data = HEAD;
          /* we scale the 8-bit alpha value to a 5-bit value by cutting off the
           * 3 leas significant bits */
          data |= (((uint32_t)vals[i].alpha << BRIGHT_SHIFT) & BRIGHT);
          data |= ((uint32_t)vals[i].color.b << BLUE_SHIFT);
          data |= ((uint32_t)vals[i].color.g << GREEN_SHIFT);
          data |= vals[i].color.r;
          shift(dev, data);
      }
      shift(dev, END);
  }