MC68HC705P9 Datasheet, PDF (123/156 Pages) Motorola, Inc – HCMOS Microcontroller Unit

ADC
Operation
Table 1. ADC I/O Register Summary
Addr.
Name
$001D ADC Data Register (ADDR)
R/W Bit 7 6
Read: Bit 7 6
Write:
Reset:
5
4
3
2
5
4
3
2
Unaffected by reset
1 Bit 0
1 Bit 0
$001E
ADC Status/Control Register (ADSCR)
Read:
Write:
CCF
ADRC ADON
0
Reset: 0
0
0
0
0
CH2 CH1 CH0
0
0
0
0
= Unimplemented
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.
Pin Functions
PC7/V_RH
The ADC uses five pins and shares them with port C:
• PC7/V_RH
• PC6/AN0, PC5/AN1, PC4/AN2, and PC3/AN3
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.
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MOTOROLA
ADC
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