MC68HC08AZ32A Datasheet, PDF (58/312 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Analog-to-Digital Converter (ADC) Module
In interrupt mode (AIEN = 1), COCO is a read-only bit that is not set at the end of a conversion. It
always reads as a 0.
1 = Conversion completed (AIEN = 0)
0 = Conversion not completed (AIEN = 0) or CPU interrupt enabled
(AIEN = 1)
NOTE
The write function of the COCO bit is reserved. When writing to the ADSCR
register, always have a 0 in the COCO bit position.
AIEN — ADC Interrupt Enable Bit
When this bit is set, an interrupt is generated at the end of an ADC conversion. The interrupt signal is
cleared when the data register is read or the status/control register is written. Reset clears the AIEN bit.
1 = ADC interrupt enabled
0 = ADC interrupt disabled
ADCO — ADC Continuous Conversion Bit
When set, the ADC will convert samples continuously and update the ADR register at the end of each
conversion. Only one conversion is allowed when this bit is cleared. Reset clears the ADCO bit.
1 = Continuous ADC conversion
0 = One ADC conversion
ADCH[4:0] — ADC Channel Select Bits
ADCH4, ADCH3, ADCH2, ADCH1, and ADCH0 form a 5-bit field which is used to select one of 15 ADC
channels. Channel selection is detailed in Table 3-1. Care should be taken when using a port pin as
both an analog and a digital input simultaneously to prevent switching noise from corrupting the analog
signal.
The ADC subsystem is turned off when the channel select bits are all set to one. This feature allows
for reduced power consumption for the MCU when the ADC is not used. Reset sets these bits.
NOTE
Recovery from the disabled state requires one conversion cycle to stabilize.
Table 3-1. Mux Channel Select
ADCH4
0
0
0
0
0
0
0
0
0
0
0
ADCH3
0
0
0
0
0
0
0
0
1
1
1
ADCH2
0
0
0
0
1
1
1
1
0
0
0
ADCH1
0
0
1
1
0
0
1
1
0
0
1
ADCH0
0
1
0
1
0
1
0
1
0
1
0
Input Select
PTB0/ATD0
PTB1/ATD1
PTB2/ATD2
PTB3/ATD3
PTB4/ATD4
PTB5/ATD5
PTB6/ATD6
PTB7/ATD7
PTD0/ATD8
PTD1/ATD9
PTD2/ATD10
— Continued on next page
MC68HC08AZ32A Data Sheet, Rev. 2
58
Freescale Semiconductor