как исправить ADC_KEYPAD_PIN' was not declared in this scope

при компиляции выдает ошибку

sketch emperature.cpp: In static member function 'static void Temperature::isr()':

temperature.cpp:2009: error: 'ADC_KEYPAD_PIN' was not declared in this scope

START_ADC(ADC_KEYPAD_PIN);

^

sketch emperature.cpp:1919:32: note: in definition of macro 'START_ADC'

#define START_ADC(pin) if (pin > 7) ADCSRB = _BV(MUX5); else ADCSRB = 0; SET_ADMUX_ADCSRA(pin)

^

temperature.cpp:2009: error: 'ADC_KEYPAD_PIN' was not declared in this scope

START_ADC(ADC_KEYPAD_PIN);

^

sketch emperature.cpp:1917:55: note: in definition of macro 'SET_ADMUX_ADCSRA'

#define SET_ADMUX_ADCSRA(pin) ADMUX = _BV(REFS0) | (pin & 0x07); SBI(ADCSRA, ADSC)

^

sketch emperature.cpp:2009:9: note: in expansion of macro 'START_ADC'

START_ADC(ADC_KEYPAD_PIN);

^

exit status 1

'ADC_KEYPAD_PIN' was not declared in this scope

подскажите где и как исправить.