mc68hc05jb4p Freescale Semiconductor, Inc, mc68hc05jb4p Datasheet - Page 101

• Manufacturer Part Number: mc68hc05jb4p
• Description: Mc68hc705jb4 Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

11.2
MC68HC05JB4
REV 2
ADC STATUS AND CONTROL REGISTER (ADSCR)
The ADSCR is a read/write register containing status and control bits for the ADC.
COCO — COnversion COmplete
ADRC — ADC RC Oscillator Control
ADON — ADC On
CH3:CH0 — Channel Select Bits
ADSCR
$000E
This read-only status bit is set when a conversion is completed, indicating that
the ADC Data Register contains a valid result. This COCO bit is cleared either
by a write to the ADSCR or a read of the ADC Data Register. Once the COCO
bit is cleared, a new conversion automatically starts. If the COCO bit is not
cleared, conversions are initiated every 32 cycles. In this continuous conver-
sion mode the ADC Data Register is refreshed with new data, every 32 cycles,
and the COCO bit remains set.
The RC oscillator option must be used if the internal processor is running below
1MHz. A stabilization time of typically 1ms is required when switching to the RC
oscillator option.
When the ADC is turned from OFF to ON, it requires a time t
rent sources to stabilize. During this time ADC conversion results may be inac-
curate. Switching the ADC off disables the internal charge pump and RC
oscillator (if selected by ADRC=1), and hence saving power.
These four bits selects one of ten ADC channels for the conversion. Channels 0
to 5 correspond to inputs AD0-AD5 on port pins PC0-PC3, PB3 and PB4
respectively. Channels 12 and 13 are the ADC reference inputs V
on port pins PC4 and PC5 respectively. Channels 14 and 15 are used for inter-
nal reference points. Table 11-1 shows the signals selected by the channel
select bits.
reset:
1 = An ADC conversion has completed; ADC Data Register ($0F)
0 = ADC conversion not completed.
1 = ADC uses RC oscillator as clock source.
0 = ADC uses internal processor clock as clock source.
1 = ADC is switched ON.
0 = ADC is switched OFF.
W
R
contains valid conversion result.
COCO
BIT 7
Figure 11-2. A/D Status and Control Register
0
Freescale Semiconductor, Inc.
For More Information On This Product,
ANALOG TO DIGITAL CONVERTER
ADRC
BIT 6
0
Go to: www.freescale.com
February 24, 1999
ADON
BIT 5
0
BIT 4
0
0
GENERAL RELEASE SPECIFICATION
BIT 3
CH3
0
BIT 2
CH2
0
ADON
BIT 1
CH1
0
RH
for the cur-
and V
BIT 0
CH0
0
RL
,