MC68HC908GR16 Datasheet, PDF (47/310 Pages) Motorola, Inc – Microcontrollers

Freescale Semiconductor, Inc.
Data Sheet — MC68HC908GR16
Section 3. Analog-to-Digital Converter (ADC)
3.1 Introduction
This section describes the 10-bit analog-to-digital converter (ADC).
3.2 Features
Features of the ADC module include:
• Eight channels with multiplexed input
• Linear successive approximation with monotonicity
• 10-bit resolution
• Single or continuous conversion
• Conversion complete flag or conversion complete interrupt
• Selectable ADC clock
• Left or right justified result
• Left justified sign data mode
3.3 Functional Description
The ADC provides eight pins for sampling external sources at pins
PTB7/AD7–PTB0/AD0. An analog multiplexer allows the single ADC converter to
select one of eight ADC channels as ADC voltage in (V_ADIN). V_ADIN is converted
by the successive approximation register-based analog-to-digital converter. When
the conversion is completed, ADC places the result in the ADC data register and
sets a flag or generates an interrupt. See Figure 3-2.
3.3.1 ADC Port I/O Pins
PTB7/AD7–PTB0/AD0 are general-purpose I/O (input/output) pins that share 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 data direction register (DDR) will not have any affect on the port pin that is
selected by the ADC. Read of a port pin in use by the ADC will return a logic 0.
MC68HC908GR16 — Rev. 1.0
MOTOROLA
Analog-to-Digital Converter (ADC)
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Data Sheet
47