MC68HC705P9 Datasheet, PDF (131/160 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
Analog-to-Digital Converter (ADC)
Operation
Addr.
$001D
$001E
Name
Bit 7 6
5
4
3
2
ADC Data Register ^{Read: Bit 7}
6
(ADDR) Write:
See page 136. _Reset:
5
4
3
2
Unaffected by reset
ADC Status/Control Register ^{Read: CCF} _{ADRC ADON}
0
(ADSCR) Write:
See page 134. _{Reset: 0}
0
0
0
0
CH2
0
0
= Unimplemented
Figure 11-2. ADC I/O Register Summary
1 Bit 0
1
Bit 0
CH1 CH0
0
0
11.4 Operation
The A/D conversion process is ratiometric, using two reference voltages,
V_RH and V_SS. Conversion accuracy is guaranteed only if V_RH is equal to
V_DD.
11.4.1 Pin Functions
The ADC uses five pins and shares them with port C:
• PC7/V_RH
• PC6/AN0, PC5/AN1, PC4/AN2, and PC3/AN3
11.4.1.1 PC7/V_RH
The voltage reference high pin (PC7/V_RH) supplies the high reference
voltage for the ratiometric conversion process. For ratiometric
conversion, the supply voltage of the analog source should be the same
as V_RH and be referenced to V_SS.
MC68HC705P9 — Rev. 4.0
MOTOROLA
Analog-to-Digital Converter (ADC)
For More Information On This Product,
Go to: www.freescale.com
Technical Data
131