MC908JL8CDWE Datasheet, PDF (145/212 Pages) Freescale Semiconductor, Inc – Microcontrollers

Chapter 10
Analog-to-Digital Converter (ADC)
10.1 Introduction
This section describes the 13-channel, 8-bit linear successive approximation analog-to-digital converter
(ADC).
10.2 Features
Features of the ADC module include:
• 13 channels with multiplexed input
• Linear successive approximation with monotonicity
• 8-bit resolution
• Single or continuous conversion
• Conversion complete flag or conversion complete interrupt
Addr.
$003C
$003D
$003E
Register Name
ADC Status and Control Read:
Register Write:
(ADSCR) _Reset:
Read:
ADC Data Register
(ADR)
Write:
Reset:
Read:
ADC Input Clock Register
(ADICLK)
Write:
Reset:
Bit 7
COCO
0
AD7
ADIV2
0
6
AIEN
0
AD6
ADIV1
0
5
ADCO
0
AD5
4
ADCH4
1
AD4
3
ADCH3
1
AD3
2
ADCH2
1
AD2
Indeterminate after reset
ADIV0
0
0
0
0
0
0
0
Figure 10-1. ADC I/O Register Summary
1
ADCH1
1
AD1
0
0
Bit 0
ADCH0
1
AD0
0
0
10.3 Functional Description
Thirteen ADC channels are available for sampling external sources at pins PTB0–PTB7, PTD0–PTD3,
and ADC12/T2CLK. An analog multiplexer allows the single ADC converter to select one of the 13 ADC
channels as ADC voltage input (ADCVIN). ADCVIN is converted by the successive approximation
register-based counters. The ADC resolution is 8 bits. When the conversion is completed, ADC puts the
result in the ADC data register and sets a flag or generates an interrupt.
Figure 10-2 shows a block diagram of the ADC.
MC68HC908JL8/JK8 • MC68HC08JL8/JK8 • MC68HC908KL8 Data Sheet, Rev. 3.1
Freescale Semiconductor
145