Roku Remote With Battery Gauge

#include <Arduino.h>
#include <Wire.h>
#include <ESP8266WiFi.h>
#include <ESP8266WebServer.h>
#include <ESP8266HTTPClient.h>
#include <EEPROM.h>
ESP8266WebServer server(80);
struct Settings {uint32_t magic; char ssid[33],pass[65],ip[16];} cfg;
const char* commands[]={"Up","Down","Left","Right","Select","Home","Back","Play"};
String last0,last1,status="Listo"; float voltage=0; bool hardware=true; uint8_t stable=255,previous=255; unsigned long changed=0,tick=0,net=0;
bool put(uint8_t addr,uint8_t v){Wire.beginTransmission(addr);Wire.write(v);return Wire.endTransmission()==0;}
bool reg8(uint8_t addr,uint8_t r,uint8_t v){Wire.beginTransmission(addr);Wire.write(r);Wire.write(v);return Wire.endTransmission()==0;}
void nibble(uint8_t n,bool rs){uint8_t v=(n<<4)|(rs?1:0);put(0x27,v);put(0x27,v|4);delayMicroseconds(2);put(0x27,v);delayMicroseconds(50);}
void lcdByte(uint8_t v,bool rs=false){nibble(v>>4,rs);nibble(v&15,rs);}
void screen(String a,String b){a=a.substring(0,16);b=b.substring(0,16);if(a==last0&&b==last1)return;last0=a;last1=b;while(a.length()<16)a+=' ';while(b.length()<16)b+=' ';lcdByte(0x80);for(char c:a)lcdByte(c,true);lcdByte(0xc0);for(char c:b)lcdByte(c,true);}
void initLCD(){delay(50);nibble(3,0);delay(5);nibble(3,0);delay(5);nibble(3,0);nibble(2,0);lcdByte(0x28);lcdByte(0x0c);lcdByte(6);lcdByte(1);delay(3);}
void page(){server.send(200,"text/html; charset=utf-8","<meta name='viewport' content='width=device-width'><h2>Control Roku</h2><form method='POST' action='/save'>Red Wi-Fi 2.4 GHz:<input name='ssid' maxlength='32' required><br>Clave Wi-Fi:<input name='pass' type='password' maxlength='64'><br>IP del Roku (Ajustes/Red/Acerca de):<input name='ip' maxlength='15' required><br><button>Guardar y reiniciar</button></form>");}
void setup(){
 Serial.begin(115200);Wire.begin(4,5);Wire.setClock(100000);Wire.setClockStretchLimit(1500);EEPROM.begin(256);EEPROM.get(0,cfg);if(cfg.magic!=0x524f4b55)memset(&cfg,0,sizeof(cfg));cfg.ssid[32]=0;cfg.pass[64]=0;cfg.ip[15]=0;
 hardware=reg8(0x20,0,0xff)&&reg8(0x20,1,0xff);reg8(0x20,0x14,0xff);reg8(0x20,0x15,0xff);reg8(0x20,0,0);reg8(0x20,1,0xfc);hardware=put(0x21,255)&&hardware;
 initLCD();screen("Control Roku","Configurando...");
 WiFi.mode(WIFI_AP_STA);WiFi.softAP("Control-Roku","RokuConfig26");if(cfg.ssid[0])WiFi.begin(cfg.ssid,cfg.pass);
 server.on("/",page);server.on("/save",HTTP_POST,[]{IPAddress ip;if(!ip.fromString(server.arg("ip"))||server.arg("ssid").isEmpty()){server.send(400,"text/plain","IP o red invalida");return;}memset(&cfg,0,sizeof(cfg));cfg.magic=0x524f4b55;server.arg("ssid").toCharArray(cfg.ssid,sizeof(cfg.ssid));server.arg("pass").toCharArray(cfg.pass,sizeof(cfg.pass));server.arg("ip").toCharArray(cfg.ip,sizeof(cfg.ip));EEPROM.put(0,cfg);EEPROM.commit();server.send(200,"text/plain","Guardado. Reiniciando.");delay(700);ESP.restart();});server.begin();
}
void sampleBattery(){
 // ADS1115: AIN0-GND, +/-4.096V, single-shot, 128 SPS.
 Wire.beginTransmission(0x48);Wire.write(1);Wire.write(0xc3);Wire.write(0x83);if(Wire.endTransmission()!=0){hardware=false;return;}delay(10);Wire.beginTransmission(0x48);Wire.write(0);Wire.endTransmission();if(Wire.requestFrom(0x48,2)!=2){hardware=false;return;}int16_t raw=(Wire.read()<<8)|Wire.read();float v=raw*0.000125f*2;voltage=voltage==0?v:voltage*0.8f+v*0.2f;
 // Indicador aproximado por tension, no contador de carga.
 const float thresholds[]={3.3,3.5,3.6,3.68,3.74,3.8,3.87,3.95,4.05,4.15};int n=0;for(float t:thresholds)if(voltage>=t)n++;uint16_t bits=(1<<n)-1;reg8(0x20,0x14,(~bits)&255);reg8(0x20,0x15,((~bits)>>8)&255);
}
void loop(){server.handleClient();unsigned long now=millis();if(now-tick>2000){tick=now;sampleBattery();String line=!hardware?"Revisar I2C":(WiFi.status()!=WL_CONNECTED?"192.168.4.1":status);screen("Bat "+String(voltage,2)+"V aprox",line);}
 if(now-net>20){net=now;if(Wire.requestFrom(0x21,1)!=1){hardware=false;return;}uint8_t v=Wire.read();if(v!=previous){previous=v;changed=now;}if(now-changed>35&&v!=stable){uint8_t pressed=stable&~v;stable=v;for(int i=0;i<8;i++)if(pressed&(1<<i)){if(voltage>0&&voltage<3.3){status="Cargar bateria";continue;}if(WiFi.status()!=WL_CONNECTED){status="Sin Wi-Fi";continue;}WiFiClient client;HTTPClient http;http.setTimeout(700);http.begin(client,String("http://")+cfg.ip+":8060/keypress/"+commands[i]);int code=http.POST("");http.end();status=code==200?String(commands[i]):"Error "+String(code);}}}delay(1);}

// Wiring verified: LCD D7 is PCF8574 P7, not a NodeMCU GPIO.
// LCD data names DB4..DB7 match the same PCF pins 4..7.