PCIF0 datasheet(216/294 Pages) ATMEL

216 / 294 page

216

9219A–RFID–01/11

Atmel ATA5505 [Preliminary]

18.11 Register Description

18.11.1

ADMUX – ADC Multiplexer Selection Register

• Bit 7:6 – REFS1:REFS0: Voltage Reference Selection Bits

These bits and AREFEN bit from the Analog Miscellaneous Control Register (AMISCR) select

the voltage reference for the ADC, as shown in Table 18-4. If these bits are changed during a

conversion, the change will not go in effect until this conversion is complete (ADIF in ADCSRA

cycles. If active channels are used, using AVCC or an external AREF higher than (AV

CC - 1V)

is not recommended, as this will affect ADC accuracy. The internal voltage reference options

may not be used if an external voltage is being applied to the AREF pin.

• Bit 5 – ADLAR: ADC Left Adjust Result

The ADLAR bit affects the presentation of the ADC conversion result in the ADC Data Regis-

ter. Write one to ADLAR to left adjust the result. Otherwise, the result is right adjusted.

Changing the ADLAR bit will affect the ADC Data Register immediately, regardless of any

ongoing conversions. For a complete description of this bit, see “ADCL and ADCH – The ADC

Data Register” on page 219.

• Bits 4:0 – MUX4:0: Analog Channel and Gain Selection Bits

These bits select which combination of analog inputs are connected to the ADC. In case of dif-

ferential input, gain selection is also made with these bits. Refer to Table 18-5 for details. If

these bits are changed during a conversion, the change will not go into effect until this

conversion is complete (ADIF in ADCSRA register is set).

Bit

6543210

REFS1

REFS0

ADLAR

MUX4

MUX3

MUX2

MUX1

MUX0

ADMUX

Read/Write

R/W

Initial Value

0000000

Table 18-4.

Voltage Reference Selections for ADC

REFS1

REFS0

AREFEN Voltage Reference (VREF) Selection

AVCC used as Voltage Reference, diconnected from AREF pin.

External Voltage Reference at AREF pin (AREF

≥ 2.0V)

Internal 1.1V Voltage Reference .

Internal 2.56V Voltage Reference .

PCIF0 Folha de dados(PDF) 216 Page - ATMEL Corporation

PCIF0 Folha de dados(HTML) 216 Page - ATMEL Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Folha de dados Download

Ligação URL