mc68hc908kx8 Freescale Semiconductor, Inc, mc68hc908kx8 Datasheet - Page 43

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

3.6 I/O Signals
The ADC module has four channels that are shared with port B pins. Refer to
the Internal Clock Generator
3.6.1 ADC Analog Power and ADC Voltage Reference Pins
The ADC analog portion uses V
Due to pin limitations, the V
MC68HC908KX8, the V
3.6.2 ADC Voltage In (ADCVIN)
ADCVIN is the input voltage signal from one of the four ADC channels to the ADC module.
3.7 I/O Registers
These I/O registers control and monitor ADC operation:
3.7.1 ADC Status and Control Register
The following paragraphs describe the function of the ADC status and control register (ADSCR).
COCO — Conversions Complete Bit
Freescale Semiconductor
•
•
•
When the AIEN bit is a 0, the COCO is a read-only bit which is set each time a conversion is completed.
This bit is cleared whenever the ADC status and control register is written or whenever the ADC data
register is read.
When the AIEN bit is a 1, the ADC module is capable of generating a CPU interrupt after each ADC
conversion. A CPU interrupt is generated if the COCO bit (ADC status control register, $003C) is at 0.
If the COCO bit is at 1, a DMA interrupt is generated. Reset clears this bit.
1 = Conversion completed (AIEN = 0)
0 = Conversion not completed (AIEN = 0)
ADC status and control register, ADSCR
ADC data register, ADR
ADC clock register, ADICLK
or CPU interrupts enabled (AIEN = 1)
Address:
Because the MC68HC908KX8 does not have a DMA module, the COCO
bit should not be set while interrupts are enabled (AIEN = 1).
Reset:
Read:
Write:
MC68HC908KX8 • MC68HC908KX2 • MC68HC08KX8 Data Sheet, Rev. 2.1
$003C
COCO
Figure 3-3. ADC Status and Control Register (ADSCR)
Bit 7
REFH
R
R
0
REFL
for voltages referenced here.
signal is internally connected to V
= Reserved
DD
AIEN
signal is internally connected to V
6
0
as its power pin and V
ADCO
5
0
NOTE
ADCH4
4
1
SS
ADCH3
as its ground pin.
3
1
DD
.
SS
ADCH2
2
1
on the MC68HC908KX8. On the
ADCH1
17.9 Trimmed Accuracy of
1
1
ADCH0
Bit 0
1
I/O Signals
43