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// vim: tabstop=4 shiftwidth=4 noexpandtab
/*
Documentation is in ws2812.h
*/
#include "ws2812.h"
#define NUMBER_NOPS_RESET 1080 // > 50 µs --> 60 µs (to be sure) = 4320 cycles @ 72 MHz = 1080 nops
#define NUMBER_NOPS_LONG 16 // 0.9 µs = 64.8 cycles @ 72 MHz = 16.2 nops --> 11.1 ns timing error
#define NUMBER_NOPS_SHORT 6 // 0.35 µs = 25.2 cycles @ 72 MHz = 6.3 nops --> 16.7 ns timing error
// public API functions:
void ws2812_init(WS2812_ARRAY *control_struct, uint32_t port, uint16_t pin, uint8_t *buffer_ptr, uint32_t array_length)
{
control_struct->gpio_port = port;
control_struct->gpio_pin = pin;
control_struct->array_buffer = buffer_ptr;
control_struct->array_length = array_length;
ws2812_clear_buffer(control_struct);
ws2812_send_reset(control_struct);
ws2812_write_buffer_to_leds(control_struct);
}
void ws2812_clear_buffer(WS2812_ARRAY *control_struct)
{
for (uint32_t i=0; i<(control_struct->array_length*3); i++){
control_struct->array_buffer[i] = 0x00;
}
}
void ws2812_write_buffer_to_leds(WS2812_ARRAY *control_struct)
{
for (uint32_t i=0; i<(control_struct->array_length); i++)
{
ws2812_send_byte(control_struct, control_struct->array_buffer[i*3+1]); // green first
ws2812_send_byte(control_struct, control_struct->array_buffer[i*3+0]); // red second
ws2812_send_byte(control_struct, control_struct->array_buffer[i*3+2]); // blue third
}
ws2812_send_reset(control_struct);
}
// internal functions:
void ws2812_send_reset(WS2812_ARRAY *control_struct)
{
gpio_clear(control_struct->gpio_port, control_struct->gpio_pin);
for (uint16_t i = 0; i < NUMBER_NOPS_RESET; i++) {
__asm__("nop");
}
}
void ws2812_send_zero(WS2812_ARRAY *control_struct)
{
gpio_set(control_struct->gpio_port, control_struct->gpio_pin);
for (uint8_t i = 0; i < NUMBER_NOPS_SHORT; i++) {
__asm__("nop");
}
gpio_clear(control_struct->gpio_port, control_struct->gpio_pin);
for (uint8_t i = 0; i < NUMBER_NOPS_LONG; i++) {
__asm__("nop");
}
}
void ws2812_send_one(WS2812_ARRAY *control_struct)
{
gpio_set(control_struct->gpio_port, control_struct->gpio_pin);
for (uint8_t i = 0; i < NUMBER_NOPS_LONG; i++) {
__asm__("nop");
}
gpio_clear(control_struct->gpio_port, control_struct->gpio_pin);
for (uint8_t i = 0; i < NUMBER_NOPS_SHORT; i++) {
__asm__("nop");
}
}
void ws2812_send_byte(WS2812_ARRAY *control_struct, uint8_t data)
{
for (int8_t i=7; i>=0; i--){
if ( (data >> i) & 0x01 ){
ws2812_send_one(control_struct);
}
else {
ws2812_send_zero(control_struct);
}
}
}
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