Renesas M16C/60 Series Hardware Manual page 210

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M16C/6N5 Group
(a) Resolution Select Function
The desired resolution can be selected using the ADCON1 register's BITS bit. If the BITS bit is set to "1"
(10-bit conversion accuracy), the A-D conversion result is stored in the ADi register (i = 0 to 7)'s bit 0 to bit 9.
If the BITS bit is set to "0" (8-bit conversion accuracy), the A-D conversion result is stored in the ADi
register's bit 0 to bit 7.
(b) Sample and Hold
If the ADCON2 register's SMP bit is set to "1" (with sample-and-hold), the conversion speed per pin is
increased to 28 φ
AD
effective in all operation modes. Select whether or not to use the sample-and-hold function before starting
A-D conversion.
(c) Extended Analog Input Pins
In one-shot and repeat modes, the ANEX0 and ANEX1 pins can be used as analog input pins. Use the
ADCON1 register's OPA1 to OPA0 bits to select whether or not use ANEX0 and ANEX1.
The A-D conversion results of ANEX0 and ANEX1 inputs are stored in the AD0 and AD1 registers,
respectively.
(d) External Operation Amp Connection Mode
Multiple analog inputs can be amplified using a single external op-amp via the ANXE0 and ANEX1 pins.
Set the ADCON1 register's OPA1 to OPA0 bits to "11
from ANi (i = 0 to 7) (Note) are output from the ANEX0 pin. Amplify this output with an external op-amp
before sending it back to the ANEX1 pin. The A-D conversion result is stored in the corresponding ADi
register. The A-D conversion speed depends on the response characteristics of the external op-amp.
Note that the ANXE0 and ANEX1 pins cannot be directly connected to each other. Figure 1.16.9 shows
an example of how to connect the pins in external operation amp.
Note: AN and AN
0i
Figure 1.16.9 External Op-amp Connection
Rev.1.00 2003.05.30 page 196
cycles for 8-bit resolution or 33 φ
can be used the same as AN
2i
ADCON2 register's ADGSEL1 to ADGSEL0 bits=00
AN
0
AN
1
AN
2
AN
3
AN
4
AN
5
AN
6
AN
7
ADGSEL1 to ADGSEL0 bits=10
AN
00
AN
01
AN
02
AN
03
AN
04
AN
05
AN
06
AN
07
ADGSEL1 to ADGSEL0 bits=11
AN
20
AN
21
AN
22
AN
23
AN
24
AN
25
AN
26
AN
27
ANEX0
ANEX1
External op-amp
cycles for 10-bit resolution. Sample-and-hold is
AD
" (external op-amp connection mode). The inputs
2
.
i
Microcomputer
2
Resistor ladder
Successive conversion
register
2
2
Comparator
A-D Converter