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