CHAPTER 10 A/D CONVERTER
Preliminary User’s Manual U16846EJ1V0UD
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(2) Analog input channel specification register (ADS)
This register specifies the analog voltage input port to be A/D converted.
ADS can be set by a 1-bit or 8-bit memory manipulation instruction.
RESET input clears this register to 00H.
Figure 10-5. Format of Analog Input Channel Specification Register (ADS)
ADS0
ADS1
0
0
0
0
0
0
Analog input channel specification
ANI0
ANI1
ANI2
ANI3
ADS0
0
1
0
1
ADS1
0
0
1
1
0
1
2
3
4
5
6
7
ADS
Address: FF29H After reset: 00H R/W
Symbol
Cautions 1. Be sure to clear bits 2 to 7 of ADS to 0.
2. If data is written to ADS, a wait cycle is generated. For details, see CHAPTER 25
CAUTIONS FOR WAIT.
(3) A/D conversion result register (ADCR)
This register is a 16-bit register that stores the A/D conversion result. The lower six bits are fixed to 0. Each time
A/D conversion ends, the conversion result is loaded from the successive approximation register, and is stored in
ADCR in order starting from the most significant bit (MSB). FF09H indicates the higher 8 bits of the conversion
result, and FF08H indicates the lower 2 bits of the conversion result.
ADCR can be read by a 16-bit memory manipulation instruction.
RESET input makes ADCR undefined.
Figure 10-6. Format of A/D Conversion Result Register (ADCR)
Symbol
Address: FF08H, FF09H After reset: Undefined R
FF09H
FF08H
0
0
0
0
0
0
ADCR
Cautions 1. When writing to the A/D converter mode register (ADM) and analog input channel
specification register (ADS), the contents of ADCR may become undefined. Read the
conversion result following conversion completion before writing to ADM and ADS. Using
timing other than the above may cause an incorrect conversion result to be read.
2. If data is read from ADCR, a wait cycle is generated. For details, see CHAPTER 25
CAUTIONS FOR WAIT.