236
AT90PWM216/316 [DATASHEET]
7710H–AVR–07/2013
If these bits are changed during a conversion, the change will not take effect until this conversion is complete (it
means while the ADIF bit in ADCSRA register is set).
20.8.2
ADC Control and Status Register A – ADCSRA
Bit 7 – ADEN: ADC Enable Bit
Set this bit to enable the ADC.
Clear this bit to disable the ADC.
Clearing this bit while a conversion is running will take effect at the end of the conversion.
Bit 6– ADSC: ADC Start Conversion Bit
Set this bit to start a conversion in single conversion mode or to start the first conversion in free running mode.
Cleared by hardware when the conversion is complete. Writing this bit to zero has no effect.
The first conversion performs the initialization of the ADC.
Bit 5 – ADATE: ADC Auto trigger Enable Bit
Set this bit to enable the auto triggering mode of the ADC.
Clear it to return in single conversion mode.
In auto trigger mode the trigger source is selected by the ADTS bits in the ADCSRB register. See
Table 20-6 on Bit 4– ADIF: ADC Interrupt Flag
Set by hardware as soon as a conversion is complete and the Data register are updated with the conversion result.
Cleared by hardware when executing the corresponding interrupt handling vector.
Alternatively, ADIF can be cleared by writing it to logical one.
Bit 3– ADIE: ADC Interrupt Enable Bit
Set this bit to activate the ADC end of conversion interrupt.
Clear it to disable the ADC end of conversion interrupt.
Bit 2, 1, 0– ADPS2, ADPS1, ADPS0: ADC Prescaler Selection Bits
These 3 bits determine the division factor between the system clock frequency and input clock of the ADC.
1011AMP0
1100AMP1 (- is ADC8, + is ADC9)
1101Reserved
1110Bandgap
1111GND
Table 20-4.
ADC Input Channel Selection
MUX3
MUX2
MUX1
MUX0
Description
Bit
7
654
3
2
1
0
ADEN
ADSC
ADATE
ADIF
ADIE
ADPS2
ADPS1
ADPS0
ADCSRA
Read/Write
R/W
R
R/W
Initial Value
0