Смотри@Slem X, если функция объявлена как void это значит она не возвращает никаких значений. Стало быть надо писать просто return; А если функция ,к примеру, int , то тогда уже пишем return {тут целое число};
Это то, что я разглядел
Вот еще увидел. char - это код символа, всегда положительное число. пишет что преобразовать к int8_t можно, но возможны нюансы.
		
		
	 
F:\PROGreIN\Arduino\Alko\GyverDrink-master\GyverDrink-master\firmware\GyverDrink_v1.2\a_setup.ino:63:0: warning: "COLOR_DEBTH" redefined
In file included from C:\Program Files (x86)\Arduino\libraries\microLED/microLED.h:25:0,
                 from F:\PROGreIN\Arduino\Alko\GyverDrink-master\GyverDrink-master\firmware\GyverDrink_v1.2\a_setup.ino:56:
C:\Program Files (x86)\Arduino\libraries\microLED/ws2812_send.h:79:0: note: this is the location of the previous definition
 #define COLOR_DEBTH 3 // по умолчанию 24 бита
 ^
In file included from F:\PROGreIN\Arduino\Alko\GyverDrink-master\GyverDrink-master\firmware\GyverDrink_v1.2\a_setup.ino:56:0:
C:\Program Files (x86)\Arduino\libraries\microLED/microLED.h:62:2: warning: 'typedef' was ignored in this declaration
 };
  ^
F:\PROGreIN\Arduino\Alko\GyverDrink-master\GyverDrink-master\firmware\GyverDrink_v1.2\c_func.ino: In function 'void serviceMode()':
F:\PROGreIN\Arduino\Alko\GyverDrink-master\GyverDrink-master\firmware\GyverDrink_v1.2\c_func.ino:6:61: warning: invalid conversion from 'byte* {aka unsigned char*}' to 'int8_t* {aka signed char*}' [-fpermissive]
     disp.runningString(serviceText, sizeof(serviceText), 150);
                                                             ^
In file included from F:\PROGreIN\Arduino\Alko\GyverDrink-master\GyverDrink-master\firmware\GyverDrink_v1.2\a_setup.ino:54:0:
C:\Program Files (x86)\Arduino\libraries\GyverTM1637/GyverTM1637.h:46:7: note: initializing argument 1 of 'void GyverTM1637::runningString(int8_t*, byte, int)'
  void runningString(int8_t DispData[], byte amount, int delayMs);    // бегущая строка (array, sizeof(array), задержка в мс)
       ^
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp: In member function 'void GyverTM1637::display(uint8_t*)':
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp:79:19: warning: invalid conversion from 'uint8_t* {aka unsigned char*}' to 'int8_t* {aka signed char*}' [-fpermissive]
  sendArray(SegData);
                   ^
In file included from C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp:1:0:
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.h:76:7: note: initializing argument 1 of 'void GyverTM1637::sendArray(int8_t*)'
  void sendArray(int8_t sendData[]);
       ^
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp: In member function 'void GyverTM1637::displayByte(uint8_t*)':
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp:92:19: warning: invalid conversion from 'uint8_t* {aka unsigned char*}' to 'int8_t* {aka signed char*}' [-fpermissive]
  sendArray(SegData);
                   ^
In file included from C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp:1:0:
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.h:76:7: note: initializing argument 1 of 'void GyverTM1637::sendArray(int8_t*)'
  void sendArray(int8_t sendData[]);
       ^
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp: In member function 'void GyverTM1637::displayClock(uint8_t, uint8_t)':
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp:191:36: warning: return-statement with a value, in function returning 'void' [-fpermissive]
  if (hrs > 99 || mins > 99) return 0;
                                    ^
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp: In member function 'void GyverTM1637::displayClockScroll(uint8_t, uint8_t, int)':
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp:201:36: warning: return-statement with a value, in function returning 'void' [-fpermissive]
  if (hrs > 99 || mins > 99) return 0;
                                    ^
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp:208:27: warning: invalid conversion from 'uint8_t* {aka unsigned char*}' to 'int8_t* {aka signed char*}' [-fpermissive]
  scroll(disp_time, delayms);
                           ^
In file included from C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp:1:0:
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.h:55:7: note: initializing argument 1 of 'void GyverTM1637::scroll(int8_t*, int)'
  void scroll(int8_t DispData[], int delayms);       // обновить значение прокруткой (массив Р¦Р?ФР, задержка РІ РјСЃ)
       ^
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp: In member function 'void GyverTM1637::displayClockTwist(uint8_t, uint8_t, int)':
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp:211:36: warning: return-statement with a value, in function returning 'void' [-fpermissive]
  if (hrs > 99 || mins > 99) return 0;
                                    ^
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp:218:26: warning: invalid conversion from 'uint8_t* {aka unsigned char*}' to 'int8_t* {aka signed char*}' [-fpermissive]
  twist(disp_time, delayms); 
                          ^
In file included from C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp:1:0:
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.h:62:7: note: initializing argument 1 of 'void GyverTM1637::twist(int8_t*, int)'
  void twist(int8_t DispData[], int delayms);        // обновить значение скручиванием (массив Р¦Р?ФР, задержка РІ РјСЃ)
       ^
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp: In member function 'void GyverTM1637::scroll(int8_t*, int)':
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp:279:34: warning: invalid conversion from 'byte* {aka unsigned char*}' to 'int8_t* {aka signed char*}' [-fpermissive]
  scrollByte(DispDataByte, delayms);
                                  ^
In file included from C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp:1:0:
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.h:58:7: note: initializing argument 1 of 'void GyverTM1637::scrollByte(int8_t*, int)'
  void scrollByte(int8_t DispData[], int delayms);      // обновить значение прокруткой (массив БАЙТ, задержка в мс)
       ^
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp: In member function 'void GyverTM1637::scroll(uint8_t, uint8_t, uint8_t, uint8_t, int)':
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp:284:43: warning: invalid conversion from 'byte* {aka unsigned char*}' to 'int8_t* {aka signed char*}' [-fpermissive]
  GyverTM1637::scrollByte(DispData, delayms);
                                           ^
In file included from C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp:1:0:
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.h:58:7: note: initializing argument 1 of 'void GyverTM1637::scrollByte(int8_t*, int)'
  void scrollByte(int8_t DispData[], int delayms);      // обновить значение прокруткой (массив БАЙТ, задержка в мс)
       ^
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp: In member function 'void GyverTM1637::scrollByte(uint8_t, uint8_t, uint8_t, uint8_t, int)':
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp:294:43: warning: invalid conversion from 'byte* {aka unsigned char*}' to 'int8_t* {aka signed char*}' [-fpermissive]
  GyverTM1637::scrollByte(DispData, delayms);
                                           ^
In file included from C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp:1:0:
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.h:58:7: note: initializing argument 1 of 'void GyverTM1637::scrollByte(int8_t*, int)'
  void scrollByte(int8_t DispData[], int delayms);      // обновить значение прокруткой (массив БАЙТ, задержка в мс)
       ^
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp: In member function 'void GyverTM1637::scrollByte(int8_t*, int)':
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp:376:23: warning: invalid conversion from 'int8_t* {aka signed char*}' to 'uint8_t* {aka unsigned char*}' [-fpermissive]
   displayByte(DispData);
                       ^
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp:81:6: note: initializing argument 1 of 'void GyverTM1637::displayByte(uint8_t*)'
 void GyverTM1637::displayByte(uint8_t DispData[])
      ^
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp: In member function 'void GyverTM1637::twist(int8_t*, int)':
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp:426:28: warning: invalid conversion from 'byte* {aka unsigned char*}' to 'int8_t* {aka signed char*}' [-fpermissive]
  twistByte(newData, delayms);
                            ^
In file included from C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.cpp:1:0:
C:\Program Files (x86)\Arduino\libraries\GyverTM1637\GyverTM1637.h:65:7: note: initializing argument 1 of 'void GyverTM1637::twistByte(int8_t*, int)'
  void twistByte(int8_t DispData[], int delayms);       // обновить значение скручиванием (массив БАЙТ, задержка в мс)