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The 3D flame in a vase

I was at an antique store recently, just browsing, not looking for anything in particular when I spied a lovely crystal vase - a steal at AUD$15.

Straight away I thought of the reflective and refractive possibilities should I shoehorn in a small solar panel and the stable joule thief (padauk version) together with the new "3D" LED PCB.

After soldering it all up and blasting the code onto the PFS154, I glued the lot into the vase and I'm happy to report that the light provided at night is quite lovely!

/*
  Candle with Three PWM

  Pseudo-random flickering to simulate a candle. Output is
  via 3xPWM channels, variables can be changed to
  alter the simulation

  Tue 17 Jan 2023 13:50:35 AEDT

*/

#include <stdint.h>
#include <stdlib.h>
#include "../device.h"
#include "../easy-pdk/calibrate.h"
#include "../auto_sysclock.h"
#include "../delay.h"
#include <stdbool.h>

#define LED4_BIT 4
#define LED0_BIT 0
#define LED3_BIT 3

uint16_t myrand = 2901;  // happy birthday

uint8_t slowcounter = 0;
uint8_t medcounter = 0;
uint8_t fastcounter = 0;
uint8_t slowstart = 0;
uint8_t slowend = 0;
uint8_t medstart = 0;
uint8_t medend = 0;
uint8_t faststart = 0;
uint8_t fastend = 0;
uint8_t faster = 0;

uint8_t waveslow[] = {20, 30, 70, 100};
uint8_t wavemed[] = {25, 40, 100, 120};
uint8_t wavefast[] = {20, 30, 120, 140};

bool fastup = true;
bool slowup = true;
bool medup = true;

void mydelay(uint8_t counter) {

  for (uint8_t thiscount = 0; thiscount <= counter; thiscount++) {
    _delay_us(1);
  }
}

uint16_t gimmerand(uint16_t small, uint16_t big) {
  myrand ^= (myrand << 13);
  myrand ^= (myrand >> 9);
  myrand ^= (myrand << 7);
  if (abs(myrand) % 13 == 0) {
    myrand = myrand - 23;
  }
  if (abs(myrand) % 17 == 0) {
    myrand = myrand + 11;
  }
  return abs(myrand) % 23 * (big - small) / 23 + small;
}

void getnewslow() {
  slowstart = gimmerand(waveslow[0], waveslow[1]);
  slowend = gimmerand(waveslow[2], waveslow[3]);
}

void getnewmed() {
  medstart = gimmerand(wavemed[0], wavemed[1]);
  medend = gimmerand(wavemed[2], wavemed[3]);
}

void getnewfast() {
  faststart = gimmerand(wavefast[0], wavefast[1]);
  fastend = gimmerand(wavefast[2], wavefast[3]);
  faster = gimmerand(2, 6);
}

// Main program
void main() {

  PAC |= (1 << LED4_BIT) | (1 << LED0_BIT) | (1 << LED3_BIT);

  // see datasheet
  PWMG1DTL = 0x00;
  PWMG1DTH = 0x00;
  PWMG1CUBL = 0xff;
  PWMG1CUBH = 0xff;
  PWMG1C = 0b10100111;
  PWMG1S = 0b00000000;

  PWMG0DTL = 0x00;
  PWMG0DTH = 0x00;
  PWMG0CUBL = 0xff;
  PWMG0CUBH = 0xff;
  PWMG0C = 0b10100111;
  PWMG0S = 0b00000000;

  PWMG2DTL = 0x00;
  PWMG2DTH = 0x00;
  PWMG2CUBL = 0xff;
  PWMG2CUBH = 0xff;
  PWMG2C = 0b10100111;
  PWMG2S = 0b00000000;

  getnewfast();
  getnewslow();
  getnewmed();
  slowcounter = slowstart;
  fastcounter = faststart;
  medcounter = medstart;

  // Main processing loop
  while (1) {

    // ramp up slow
    if (slowup) {
      slowcounter++;
      if (slowcounter > slowend) { // ramp finished so switch boolean
        slowup = !slowup;
      }
    }
    else {
      // ramp down slow
      slowcounter--;
      if (slowcounter < slowstart) { // ramp finished so switch boolean
        slowup = !slowup;
        getnewslow();
      }
    }

    // ramp up med
    if (medup) {
      medcounter++;
      if (medcounter > medend) { // ramp finished so switch boolean
        medup = !medup;
      }
    }
    else {
      // ramp down med
      medcounter--;
      if (medcounter < medstart) { // ramp finished so switch boolean
        medup = !medup;
        getnewmed();
      }
    }

    // ramp up fast
    if (fastup) {
      fastcounter = fastcounter + faster;
      if (fastcounter > fastend) { // ramp finished so switch boolean
        fastup = !fastup;
      }
    }
    else {
      // ramp down fast
      fastcounter = fastcounter - faster;
      if (fastcounter < faststart) { // ramp finished so switch boolean
        fastup = !fastup;
        getnewfast();
      }
    }
    // delay + a re-purposed random for ramp speeds
    mydelay(15 + faster);

    PWMG1DTL = slowcounter & 255;
    PWMG1DTH = slowcounter;
    PWMG0DTL = fastcounter & 255;
    PWMG0DTH = fastcounter;
    PWMG2DTL = medcounter & 255;
    PWMG2DTH = medcounter;

  }
}

// Startup code - Setup/calibrate system clock
unsigned char _sdcc_external_startup(void) {

  CLKMD = CLKMD_ILRC | CLKMD_ENABLE_ILRC | CLKMD_ENABLE_IHRC;
  CLKMD = CLKMD_ILRC | CLKMD_ENABLE_ILRC;
  PDK_SET_SYSCLOCK(SYSCLOCK_ILRC);
  EASY_PDK_CALIBRATE_ILRC(50000, 4000);

  return 0;
}

Judge the result for yourself - but this one has been chugging away at night time for a few weeks now and is a bit of a hit with the executive!