Rainbow-electronics ATmega64M1 Manuel d'utilisateur télécharger pdf (Page 247)

247

8209A–AVR–08/09

ATmega16M1/32M1/64M1

• Bit 6 – ISRCEN: Current Source Enable

Set this bit to source a 100µA current to the AREF pin.

Clear this bit to use AREF pin as Analog Reference pin.

• Bit 5 – AREFEN: Analog Reference pin Enable

Set this bit to connect the internal AREF circuit to the AREF pin.

Clear this bit to disconnect the internal AREF circuit from the AREF pin.

• Bit 4 – Res: Reserved

This bit is reserved and will always read as zero.

• Bit 3:0– ADTS[3:0]: ADC Auto Trigger Source Selection Bits

These bits are only necessary in case the ADC works in auto trigger mode. It means if ADATE

bit in ADCSRA register is set.

In accordance with the Table 22-7, these 3 bits select the interrupt event which will generate the

trigger of the start of conversion. The start of conversion will be generated by the rising edge of

the selected interrupt flag whether the interrupt is enabled or not. In case of trig on PSCnASY

event, there is no flag. So in this case a conversion will start each time the trig event appears

and the previous conversion is completed..

22.10.5 ADCH and ADCL – ADC Result Data Registers

When an ADC conversion is complete, the conversion results are stored in these two result data

registers.

When the ADCL register is read, the two ADC result data registers can’t be updated until the

ADCH register has also been read.

Table 22-7. ADC Auto Trigger Source Selection

ADTS[3:0] Description

0000 Free Running Mode

0001 External Interrupt Request 0

0010 Timer/Counter0 Compare Match

0011 Timer/Counter0 Overflow

0100 Timer/Counter1 Compare Match B

0101 Timer/Counter1 Overflow

0110 Timer/Counter1 Capture Event

0111 PSC Module 0 Synchronization Signal

1000 PSC Module 1 Synchronization Signal

1001 PSC Module 2 Synchronization Signal

1010 Analog comparator 0

1011 Analog comparator 1

1100 Analog comparator 2

1101 Analog comparator 3

1110 Reserved

1111 Reserved

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Rainbow-electronics ATmega64M1 Manuel d'utilisateur Page 247