4 * Controls APA102 RGB-LEDs
5 * Author: Mikkel (Duckle29 on github)
7 * Dec 22th, 2017 v1.0a Initial Version
9 * This program is free software: you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation, either version 2 of the License, or
12 * (at your option) any later version.
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
19 * You should have received a copy of the GNU General Public License
20 * along with this program. If not, see <http://www.gnu.org/licenses/>.
24 #include <avr/interrupt.h>
26 #include <util/delay.h>
29 // Setleds for standard RGB
30 void inline apa102_setleds(LED_TYPE *ledarray, uint16_t leds) { apa102_setleds_pin(ledarray, leds, _BV(RGB_DI_PIN & 0xF), _BV(RGB_CLK_PIN & 0xF)); }
32 void static inline apa102_setleds_pin(LED_TYPE *ledarray, uint16_t leds, uint8_t pinmask_DI, uint8_t pinmask_CLK) {
33 pinMode(RGB_DI_PIN, PinDirectionOutput);
34 pinMode(RGB_CLK_PIN, PinDirectionOutput);
36 apa102_send_array((uint8_t *)ledarray, leds)
39 void apa102_send_array(uint8_t *data, uint16_t leds) { // Data is struct of 3 bytes. RGB - leds is number of leds in data
42 apa102_send_frame(0xFF000000 | (data->b << 16) | (data->g << 8) | data->r);
45 apa102_end_frame(leds);
48 void apa102_send_frame(uint32_t frame) {
49 for (uint32_t i = 0xFF; i > 0;) {
50 apa102_send_byte(frame & i);
55 void apa102_start_frame() { apa102_send_frame(0); }
57 void apa102_end_frame(uint16_t leds) {
58 // This function has been taken from: https://github.com/pololu/apa102-arduino/blob/master/APA102.h
59 // and adapted. The code is MIT licensed. I think thats compatible?
61 // We need to send some more bytes to ensure that all the LEDs in the
62 // chain see their new color and start displaying it.
64 // The data stream seen by the last LED in the chain will be delayed by
65 // (count - 1) clock edges, because each LED before it inverts the clock
66 // line and delays the data by one clock edge. Therefore, to make sure
67 // the last LED actually receives the data we wrote, the number of extra
68 // edges we send at the end of the frame must be at least (count - 1).
69 // For the APA102C, that is sufficient.
71 // The SK9822 only updates after it sees 32 zero bits followed by one more
72 // rising edge. To avoid having the update time depend on the color of
73 // the last LED, we send a dummy 0xFF byte. (Unfortunately, this means
74 // that partial updates of the beginning of an LED strip are not possible;
75 // the LED after the last one you are trying to update will be black.)
76 // After that, to ensure that the last LED in the chain sees 32 zero bits
77 // and a rising edge, we need to send at least 65 + (count - 1) edges. It
78 // is sufficent and simpler to just send (5 + count/16) bytes of zeros.
80 // We are ignoring the specification for the end frame in the APA102/SK9822
81 // datasheets because it does not actually ensure that all the LEDs will
82 // start displaying their new colors right away.
84 apa102_send_byte(0xFF);
85 for (uint16_t i = 0; i < 5 + leds / 16; i++) {
90 void apa102_send_byte(uint8_t byte) {
92 for (i = 0; i < 8; i++) {
93 digitalWrite(RGB_DI_PIN, !!(byte & (1 << (7-i)));
94 digitalWrite(RGB_CLK_PIN, PinLevelHigh);