/* Fumot Digital Box 12000 vape charlieplex led display driver, 22.12.2024
    --- i do not use vapes, and do not suggest anyone to buy or try ---

how does it work?
a timer regulary calls a interrupt routine, lighting up one of 24 segments every cycle.
the displaybuffer is a 32bit int as binary (24 bit used), containing following (from LSB):
7 bits of second 7 segment digit (ones)
7 bits of first  7 segment digit (tens)
1 bit for flash symbol
1 bit for percent symbol
5 bits for level container
4 bits for rgb level segments
FPS can be set between ca. 50Hz (flicker when shaken) up to 8kHz.
brightness is good with 100Ohms on each of the 6 lanes, independend from speed.
everything is controlled by precalculated and direct register manipulation,
while the slower digits calculation is only done once per change. */

#include "Arduino.h"                          // esp32c3, ACM-native usb, usb_cdc enabled
uint8_t seg[10]={0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,0x7F,0x6F};  // 7 segment font
uint8_t clo[25]={0,1,0,2,0,3,4,1,2,3,3,4,4,4,2,1,3,4,0,1,2,3,2,1,0};  // charlieplex lowpin
uint8_t chi[25]={1,0,2,0,3,0,0,2,1,2,1,1,2,3,3,3,5,5,5,5,5,4,4,4,4};  //      .. and highpin
hw_timer_t *t=NULL;int32_t b,port;                                    // buffers nstuff
uint8_t i,s,pin[6]={4,5,6,7,20,21};    //  *** CHANGE THIS ***        // display io pins

void set(uint8_t n){b=seg[n%10]|seg[n/10]<<7|0x1FFC000;}     // generate display buffer

void IRAM_ATTR isr(){
  REG_WRITE(GPIO_ENABLE_W1TC_REG,port);                      // set display ports to input
  if(bitRead(b,s)){                                          // if segment should be lit..
    REG_WRITE(GPIO_ENABLE_W1TS_REG,1<<clo[s]|1<<chi[s]);     // set its plexpins as output
    REG_WRITE(GPIO_OUT_W1TC_REG,1<<clo[s]);                  // set lowpin
    REG_WRITE(GPIO_OUT_W1TS_REG,1<<chi[s]);}                 // and highpin
  if(++s>25)s=0;}                                            // iterate through segments

void setup(){
  for(i=0;i< 6;i++){pinMode(pin[i],INPUT);port|=1<<pin[i];}  // configure pins & generate portmask
  for(i=0;i<25;i++){clo[i]=pin[clo[i]];chi[i]=pin[chi[i]];}  // align plex to userpins
  t=timerBegin(200000);timerAttachInterrupt(t,&isr);timerAlarm(t,1,true,0);} // 1kHz-200kHz

void loop(){
  if(++i>99)i=0;set(i);
  delay(100);}