MC68HC05P18A Datasheet, PDF (94/130 Pages) Freescale Semiconductor, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
Analog-to-Digital (A/D) Converter
11.5.3 Multi-Channel Operation
An input multiplexer allows the A/D converter to select from one of four
external analog signals. Port C pins PC3–PC6 are shared with the inputs
to the multiplexer.
11.6 A/D Status and Control Register
The A/D status and control register (ADSCR) reports the completion of
A/D conversion and provides control over:
• Oscillator selection
• Analog subsystem power
• Input channel selection
See Figure 11-1.
Address: $001E
Bit 7
6
5
4
3
2
1
Bit 0
Read: CC
Write:
0
R
ADON
0
CH2
CH1
CH0
Reset: 0
0
0
0
0
0
0
0
= Unimplemented
R = Reserved
Figure 11-1. A/D Status and Control Register (ADSCR)
CC — Conversion Complete Bit
This read-only status bit is set when a conversion sequence has
completed and data is ready to be read from the ADC register. CC is
cleared when a channel is selected for conversion, when data is read
from the ADC register, or when the A/D subsystem is turned off. Once
a conversion is started, conversions of the selected channel continue
every 32 PH2 clock cycles until the ADSC register is written to again.
During continuous conversion operation, the ADC register is updated
with new data, and the CC bit is set, every 32 PH2 clock cycles. Also,
data from the previous conversion is overwritten regardless of the
state of the CC bit.
Technical Data
Analog-to-Digital (A/D) Converter
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MC68HC05P18A