mc68hc908kx8 Freescale Semiconductor, Inc, mc68hc908kx8 Datasheet - Page 39

• Manufacturer Part Number: mc68hc908kx8
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Chapter 3
Analog-to-Digital Converter (ADC)
3.1 Introduction
This section describes the 8-bit analog-to-digital converter (ADC).
3.2 Features
Features of the ADC module include:
3.3 Functional Description
The ADC provides four pins for sampling external sources at pins PTB3
allows the single ADC converter to select one of four ADC channels as ADC voltage in (ADCVIN).
ADCVIN is converted by the successive approximation register-based counters. When the conversion is
completed, ADC places the result in the ADC data register and sets a flag or generates an interrupt. See
Figure
The MC68HC908KX8 uses V
3.3.1 ADC Port I/O Pins
PTB3–PTB0 are general-purpose input/output (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 I/O logic by forcing that pin as input to the ADC. The remaining ADC channels/port pins
are controlled by the port I/O logic and can be used as general-purpose I/O. Writes to the port register or
DDR will not have any effect on the port pin that is selected by the ADC. Read of a port pin which is in
use by the ADC will return a logic 0 if the corresponding DDR bit is at 0. If the DDR bit is at 1, the value
in the port data latch is read.
Freescale Semiconductor
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Four channels with multiplexed input
Linear successive approximation
8-bit resolution
Single or continuous conversion
Conversion complete flag or conversion complete interrupt
Selectable ADC clock
3-2.
MC68HC908KX8 • MC68HC908KX2 • MC68HC08KX8 Data Sheet, Rev. 2.1
DD
as the high voltage reference.
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PTB0. An analog multiplexer
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