CH552-Macropad-mini

// ===================================================================================
// NeoPixel (Addressable LED) Functions for CH551, CH552 and CH554            * v1.1 *
// ===================================================================================
//
// Basic control functions for 800kHz addressable LEDs (NeoPixel). A simplified 
// protocol is used which should work with most LEDs.
//
// The following must be defined in config.h:
// PIN_NEO - pin connected to DATA-IN of the pixel strip (via a ~330 ohms resistor).
// NEO_GRB - type of pixel: NEO_GRB or NEO_RGB
// System clock frequency must be at least 6 MHz.
//
// Further information:     https://github.com/wagiminator/ATtiny13-NeoController
// 2023 by Stefan Wagner:   https://github.com/wagiminator

// ===================================================================================
// Libraries, Variables and Constants
// ===================================================================================
#include "neo.h"

#define NEOPIN PIN_asm(PIN_NEO)     // convert PIN_NEO for inline assembly

// ===================================================================================
// Protocol Delays
// ===================================================================================
// There are three essential conditions:
// - T0H (HIGH-time for "0"-bit) must be max.  500ns
// - T1H (HIGH-time for "1"-bit) must be min.  625ns
// - TCT (total clock time) must be      min. 1150ns
// The bit transmission loop takes 11 clock cycles.
#if F_CPU == 24000000       // 24 MHz system clock
  #define T1H_DELAY \
    nop             \
    nop             \
    nop             \
    nop             \
    nop             \
    nop             \
    nop             \
    nop             \
    nop             \
    nop             \
    nop                     // 15 - 4 = 11 clock cycles for min 625ns
  #define TCT_DELAY \
    nop             \
    nop             \
    nop             \
    nop             \
    nop             \
    nop                     // 28 - 11 - 11 = 6 clock cycles for min 1150ns
#elif F_CPU == 16000000     // 16 MHz system clock
  #define T1H_DELAY \
    nop             \
    nop             \
    nop             \
    nop             \
    nop             \
    nop                     // 10 - 4 = 6 clock cycles for min 625ns
  #define TCT_DELAY \
    nop             \
    nop                     // 19 - 6 - 11 = 2 clock cycles for min 1150ns
#elif F_CPU == 12000000     // 12 MHz system clock
  #define T1H_DELAY \
    nop             \
    nop             \
    nop             \
    nop                     // 8 - 4 = 4 clock cycles for min 625ns
  #define TCT_DELAY         // 14 - 4 - 11 < 0 clock cycles for min 1150ns
#elif F_CPU == 6000000      // 13 MHz system clock
  #define T1H_DELAY         // 4 - 4 = 0 clock cycles for min 625ns
  #define TCT_DELAY         // 7 - 0 - 11 < 0 clock cycles for min 1150ns
#else
  #error Unsupported system clock frequency for NeoPixels!
#endif

// ===================================================================================
// Send a Data Byte to the Pixels String
// ===================================================================================
// This is the most time sensitive part. Outside of the function, it must be 
// ensured that interrupts are disabled and that the time between the 
// transmission of the individual bytes is less than the pixel's latch time.
void NEO_sendByte(uint8_t data) { 
  data;                 // stop unreferenced argument warning
  __asm
    .even
    mov  r7, #8         ; 2 CLK - 8 bits to transfer
    xch  a, dpl         ; 2 CLK - data byte -> accu
    01$:
    rlc  a              ; 1 CLK - data bit -> carry (MSB first)
    setb NEOPIN         ; 2 CLK - NEO pin HIGH
    mov  NEOPIN, c      ; 2 CLK - "0"-bit? -> NEO pin LOW now
    T1H_DELAY           ; x CLK - TH1 delay
    clr  NEOPIN         ; 2 CLK - "1"-bit? -> NEO pin LOW a little later
    TCT_DELAY           ; y CLK - TCT delay
    djnz r7, 01$        ; 2/4|5|6 CLK - repeat for all bits
  __endasm;
}

// ===================================================================================
// Write Color to a Single Pixel
// ===================================================================================
void NEO_writeColor(uint8_t r, uint8_t g, uint8_t b) {
  #if defined (NEO_GRB)
    NEO_sendByte(g); NEO_sendByte(r); NEO_sendByte(b);
  #elif defined (NEO_RGB)
    NEO_sendByte(r); NEO_sendByte(g); NEO_sendByte(b);
  #else
    #error Wrong or missing NeoPixel type definition!
  #endif
}

// ===================================================================================
// Write Hue Value (0..191) and Brightness (0..2) to a Single Pixel
// ===================================================================================
void NEO_writeHue(uint8_t hue, uint8_t bright) {
  uint8_t phase = hue >> 6;
  uint8_t step  = (hue & 63) << bright;
  uint8_t nstep = (63 << bright) - step;
  switch(phase) {
    case 0:   NEO_writeColor(nstep,  step,     0); break;
    case 1:   NEO_writeColor(    0, nstep,  step); break;
    case 2:   NEO_writeColor( step,     0, nstep); break;
    default:  break;
  }
}