mc68hc908kx8 Freescale Semiconductor, Inc, mc68hc908kx8 Datasheet - Page 44

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

Analog-to-Digital Converter (ADC)
AIEN — ADC Interrupt Enable Bit
ADCO — ADC Continuous Conversion Bit
ADCH4–ADCH0 — ADC Channel Select Bits
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When this bit is set, an interrupt is generated at the end of an ADC conversion. The interrupt signal is
cleared when the ADR register is read or the ADSCR register is written. Reset clears the AIEN bit.
When set, the ADC will convert samples continuously and update the ADR register at the end of each
conversion. Only one conversion is allowed when this bit is cleared. Reset clears the ADCO bit.
ADCH4–ADCH0 form a 5-bit field which is used to select the input for the A/D measurement.
The choices are one of four ADC channels, as well as V
Table
simultaneously to prevent switching noise from corrupting the analog signal.
The ADC subsystem is turned off when the channel select bits are all set to 1. This feature allows for
reduced power consumption for the MCU when the ADC is not used. Reset sets these bits.
1 = ADC interrupt enabled
0 = ADC interrupt disabled
1 = Continuous ADC conversion
0 = One ADC conversion
3-1. Care should be taken when using a port pin as both an analog and a digital input
1. If any unused channels are selected, the resulting ADC conversion will be unknown.
2. The voltage levels supplied from internal reference nodes as specified in the table are used
Recovery from the disabled state requires one conversion cycle to stabilize.
ADCH4
to verify the operation of the ADC converter both in production test and for user applica-
tions.
—
0
0
0
0
0
1
1
1
1
MC68HC908KX8 • MC68HC908KX2 • MC68HC08KX8 Data Sheet, Rev. 2.1
ADCH3
—
0
0
0
0
0
1
1
1
1
Table 3-1. Mux Channel Select
ADCH2
—
0
0
0
0
1
1
1
1
1
NOTE
ADCH1
—
0
0
1
1
0
0
0
1
1
REFH
ADCH0
—
and V
0
1
0
1
0
0
1
0
1
SS
. Input selection is detailed in
ADC power off
Input Select
Unused
Unused
V
V
SSAD
PTB0
PTB1
PTB2
PTB3
REFH
—
(2)
(2)
Freescale Semiconductor
(1)
(1)