Rainbow-electronics ATmega64C1 Manuel d'utilisateur télécharger pdf (Page 251)

251

7647A–AVR–02/08

ATmega32/64/M1/C1

18.11 Amplifier Control Registers

The configuration of the amplifiers are controlled via two dedicated registers AMP0CSR and

AMP1CSR. Then the start of conversion is done via the ADC control and status registers.

The conversion result is stored on ADCH and ADCL register which contain respectively the most

significant bits and the less significant bits.

18.11.1 Amplifier 0 Control and Status register – AMP0CSR

• Bit 7 – AMP0EN: Amplifier 0 Enable Bit

Set this bit to enable the Amplifier 0.

Clear this bit to disable the Amplifier 0.

Clearing this bit while a conversion is running will take effect at the end of the conversion.

Warning: Always clear AMP0TS0:1 when clearing AMP0EN.

• Bit 6 – AMP0IS: Amplifier 0 Input Shunt

Set this bit to short-circuit the Amplifier 0 input.

Clear this bit to normally use the Amplifier 0.

• Bit 5, 4 – AMP0G1, 0: Amplifier 0 Gain Selection Bits

These 2 bits determine the gain of the amplifier 0.

The different setting are shown in Table 18-8.

To ensure an accurate result, after the gain value has been changed, the amplifier input needs

to have a quite stable input value during at least 4 Amplifier synchronization clock periods.

• Bit 3 – AMPCMP0: Amplifier 0 - Comparator 0 connection

Set this bit to connect the amplifier 0 to the comparator 0 positive input. In this configuration the

comparator clock is adapted to the amplifier clock and AMP0TS2,AMP0TS1, AMP0TS0 bits

have no effect.

Clear this bit to normally use the Amplifier 0.

• Bit 2:0 – AMP0TS2,AMP0TS1,AMP0TS0: Amplifier 0 Clock Source Selection Bits

Bit 76543210

AMP0EN AMP0IS AMP0G1 AMP0G0 AMPCMP0 AMP0TS2 AMP0TS1 AMP0TS0 AMP0CSR

Read/Write R/W R/W R/W R/W R/W R/W R/W R/W

Initial Value 0 0 0 0 0 0 0 0

Table 18-8. Amplifier 0 Gain Selection

AMP0G1 AMP0G0 Description

00Gain 5

01Gain 10

10Gain 20

11Gain 40

1 2 ... 246 247 248 249 250 251 252 253 254 255 256 ... 365 366

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Rainbow-electronics ATmega64C1 Manuel d'utilisateur Page 251