MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1
Freescale Semiconductor 45
Chapter 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:
10 channels with multiplexed input
Linear successive approximation
10-bit resolution, 8-bit accuracy
Single or continuous conversion
Conversion complete flag or conversion complete interrupt
Selectable ADC clock
Left or right justified result
Left justified sign data mode
High impedance buffered ADC input

3.3 Functional Description

Ten ADC channels are available for sampling external sources at pins PTC1/ATD9:PTC0/ATD8 and
PTB7/ATD7:PTB0/ATD0. To achieve the best possible accuracy, these pins are implemented as
input-only pins when the analog-to-digital (A/D) feature is enabled. An analog multiplexer allows the single
ADC to select one of the 10 ADC channels as ADC voltage IN (ADCVIN). ADCVIN is converted by the
successive approximation algorithm. When the conversion is completed, the ADC places the result in the
ADC data register (ADRH and ADRL) and sets a flag or generates an interrupt. See Figure 3-2.