Rainbow-electronics ATmega163L Uživatelský manuál stáhnout pdf (Strana 94)

ATmega163(L)

Figure 61. ADC Timing Diagram, Free Run Conversion

ADC Noise Canceler Function

The ADC features a noise canceler that enables conversion during ADC Noise Reduction mode (see “Sleep Modes” on

page 31) to reduce noise induced from the CPU core and other I/O peripherals. If other I/O peripherals must be active dur-

ing conversion, this mode works equivalently for Idle mode. To make use of this feature, the following procedure should be

used:

1. Make sure that the ADC is enabled and is not busy converting. Single Conversion Mode must be selected and the

ADC conversion complete interrupt must be enabled.

ADEN = 1

ADSC = 0

ADFR = 0

ADIE = 1

2. Enter ADC Noise Reduction mode (or Idle mode). The ADC will start a conversion once the CPU has been halted.

3. If no other interrupts occur before the ADC conversion completes, the ADC interrupt will wake up the CPU and exe-

cute the ADC Conversion Complete interrupt routine.

11 12 13

Sign and MSB of result

LSB of result

ADC clock

ADSC

ADIF

ADCH

ADCL

Cycle number

One Conversion Next Conversion

Conversion

complete

Sample & hold

MUX and REFS

update

Table 39. ADC Conversion Time

Condition

Sample & Hold (cycles

from start of

conversion) Conversion Time (cycles) Conversion Time (µs)

Extended Conversion 13.5 25 125 - 500

Normal Conversions 1.5 13 65 - 260

1 2 ... 89 90 91 92 93 94 95 96 97 98 99 ... 155 156

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Rainbow-electronics ATmega163L Uživatelský manuál Strana 94