Chapter 10 Analog-to-Digital Converter (S08ADC12V1)
MC9S08DZ128 Series Data Sheet, Rev. 1
Freescale Semiconductor
221
10.4
Functional Description
The ADC module is disabled during reset or when the ADCH bits are all high. The module is idle when a
conversion has completed and another conversion has not been initiated. When idle, the module is in its
lowest power state.
The ADC can perform an analog-to-digital conversion on any of the software selectable channels. In 12-bit
and 10-bit mode, the selected channel voltage is converted by a successive approximation algorithm into
a 12-bit digital result. In 8-bit mode, the selected channel voltage is converted by a successive
approximation algorithm into a 9-bit digital result.
When the conversion is completed, the result is placed in the data registers (ADCRH and ADCRL). In
10-bit mode, the result is rounded to 10 bits and placed in the data registers (ADCRH and ADCRL). In
8-bit mode, the result is rounded to 8 bits and placed in ADCRL. The conversion complete ag (COCO)
is then set and an interrupt is generated if the conversion complete interrupt has been enabled (AIEN = 1).
The ADC module has the capability of automatically comparing the result of a conversion with the
contents of its compare registers. The compare function is enabled by setting the ACFE bit and operates
with any of the conversion modes and congurations.
Table 10-12. APCTL3 Register Field Descriptions
Field
Description
7
ADPC23
ADC Pin Control 23. ADPC23 controls the pin associated with channel AD23.
0 AD23 pin I/O control enabled
1 AD23 pin I/O control disabled
6
ADPC22
ADC Pin Control 22. ADPC22 controls the pin associated with channel AD22.
0 AD22 pin I/O control enabled
1 AD22 pin I/O control disabled
5
ADPC21
ADC Pin Control 21. ADPC21 controls the pin associated with channel AD21.
0 AD21 pin I/O control enabled
1 AD21 pin I/O control disabled
4
ADPC20
ADC Pin Control 20. ADPC20 controls the pin associated with channel AD20.
0 AD20 pin I/O control enabled
1 AD20 pin I/O control disabled
3
ADPC19
ADC Pin Control 19. ADPC19 controls the pin associated with channel AD19.
0 AD19 pin I/O control enabled
1 AD19 pin I/O control disabled
2
ADPC18
ADC Pin Control 18. ADPC18 controls the pin associated with channel AD18.
0 AD18 pin I/O control enabled
1 AD18 pin I/O control disabled
1
ADPC17
ADC Pin Control 17. ADPC17 controls the pin associated with channel AD17.
0 AD17 pin I/O control enabled
1 AD17 pin I/O control disabled
0
ADPC16
ADC Pin Control 16. ADPC16 controls the pin associated with channel AD16.
0 AD16 pin I/O control enabled
1 AD16 pin I/O control disabled