Analog-to-Digital Converter (ADC)
Functional Description
MC68HC908MR16/MC68HC908MR32 — Rev. 4.0 Advance Information
MOTOROLA Analog-to-Digital Converter (ADC) 343
Figure 19-1. ADC Block Diagram
19.4.1 ADC Port I/O Pins
PTC1/ATD9:PTC0/ATD8 and PTB7/ATD7:PTB0/ATD0 are
general-purpose I/O pins that are shared with the ADC channels.
The channel select bits define which ADC channel/port pin will be used
as the input signal. The ADC overrides the port logic when that port is
selected by the ADC multiplexer. The remaining ADC channels/port pins
are controlled by the port logic and can be used as general-purpose
input/output (I/O) pins. Writes to the port register or DDR will not have
any effect on the port pin that is selected by the ADC. Re ad of a port pin
which is in use by the ADC will return a logic 0.
INTERNAL
DATA BUS
READ PTB/PTC
PTB/Cx
INTERRUPT
LOGIC CHANNEL
SELECT
ADC
CLOCK
GENERATOR
CONVERSION
COMPLETE
ADC VOLTAGE IN
ADVIN
ADC CLOCK
CGMXCLK
BUS CLOCK
ADCH[4:0]
ADC DATA REGISTERS
ADIV[2:0] ADICLK
AIEN COCO/IDMAS
DISABLE
ADC CHANNEL x
PTx