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/* Copyright 2020 Aldehir Rojas
* Copyright 2017 Mikkel (Duckle29)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "apa102.h"
#include "gpio.h"
#ifndef APA102_NOPS
# if defined(__AVR__)
# define APA102_NOPS 0 // AVR at 16 MHz already spends 62.5 ns per clock, so no extra delay is needed
# elif defined(PROTOCOL_CHIBIOS)
# include "hal.h"
# include "chibios_config.h"
# if defined(STM32F0XX) || defined(STM32F1XX) || defined(STM32F3XX) || defined(STM32F4XX) || defined(STM32L0XX) || defined(GD32VF103) || defined(MCU_RP)
# define APA102_NOPS (100 / (1000000000L / (CPU_CLOCK / 4))) // This calculates how many loops of 4 nops to run to delay 100 ns
# else
# error APA102_NOPS configuration required
# define APA102_NOPS 0 // this just pleases the compile so the above error is easier to spot
# endif
# endif
#endif
#define io_wait \
do { \
for (int i = 0; i < APA102_NOPS; i++) { \
__asm__ volatile("nop\n\t" \
"nop\n\t" \
"nop\n\t" \
"nop\n\t"); \
} \
} while (0)
#define APA102_SEND_BIT(byte, bit) \
do { \
gpio_write_pin(APA102_DI_PIN, (byte >> bit) & 1); \
io_wait; \
gpio_write_pin_high(APA102_CI_PIN); \
io_wait; \
gpio_write_pin_low(APA102_CI_PIN); \
io_wait; \
} while (0)
uint8_t apa102_led_brightness = APA102_DEFAULT_BRIGHTNESS;
static void apa102_send_byte(uint8_t byte) {
APA102_SEND_BIT(byte, 7);
APA102_SEND_BIT(byte, 6);
APA102_SEND_BIT(byte, 5);
APA102_SEND_BIT(byte, 4);
APA102_SEND_BIT(byte, 3);
APA102_SEND_BIT(byte, 2);
APA102_SEND_BIT(byte, 1);
APA102_SEND_BIT(byte, 0);
}
static void apa102_start_frame(void) {
apa102_init();
for (uint16_t i = 0; i < 4; i++) {
apa102_send_byte(0);
}
}
static void apa102_end_frame(uint16_t num_leds) {
// This function has been taken from: https://github.com/pololu/apa102-arduino/blob/master/APA102.h
// and adapted. The code is MIT licensed. I think thats compatible?
//
// The data stream seen by the last LED in the chain will be delayed by
// (count - 1) clock edges, because each LED before it inverts the clock
// line and delays the data by one clock edge. Therefore, to make sure
// the last LED actually receives the data we wrote, the number of extra
// edges we send at the end of the frame must be at least (count - 1).
//
// Assuming we only want to send these edges in groups of size K, the
// C/C++ expression for the minimum number of groups to send is:
//
// ((count - 1) + (K - 1)) / K
//
// The C/C++ expression above is just (count - 1) divided by K,
// rounded up to the nearest whole number if there is a remainder.
//
// We set K to 16 and use the formula above as the number of frame-end
// bytes to transfer. Each byte has 16 clock edges.
//
// We are ignoring the specification for the end frame in the APA102
// datasheet, which says to send 0xFF four times, because it does not work
// when you have 66 LEDs or more, and also it results in unwanted white
// pixels if you try to update fewer LEDs than are on your LED strip.
uint16_t iterations = (num_leds + 14) / 16;
for (uint16_t i = 0; i < iterations; i++) {
apa102_send_byte(0);
}
apa102_init();
}
static void apa102_send_frame(uint8_t red, uint8_t green, uint8_t blue, uint8_t brightness) {
apa102_send_byte(0b11100000 | brightness);
apa102_send_byte(blue);
apa102_send_byte(green);
apa102_send_byte(red);
}
void apa102_init(void) {
gpio_set_pin_output(APA102_DI_PIN);
gpio_set_pin_output(APA102_CI_PIN);
gpio_write_pin_low(APA102_DI_PIN);
gpio_write_pin_low(APA102_CI_PIN);
}
void apa102_setleds(rgb_led_t *start_led, uint16_t num_leds) {
rgb_led_t *end = start_led + num_leds;
apa102_start_frame();
for (rgb_led_t *led = start_led; led < end; led++) {
apa102_send_frame(led->r, led->g, led->b, apa102_led_brightness);
}
apa102_end_frame(num_leds);
}
void apa102_set_brightness(uint8_t brightness) {
if (brightness > APA102_MAX_BRIGHTNESS) {
apa102_led_brightness = APA102_MAX_BRIGHTNESS;
} else if (brightness < 0) {
apa102_led_brightness = 0;
} else {
apa102_led_brightness = brightness;
}
}
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