M32C80 Datasheet, PDF (252/352 Pages) Renesas Technology Corp – 16/32-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M32C/80 SERIES

M32C/80 Group
17. A/D Converter
17.2.5 Extended Analog Input Pins
In one-shot mode and repeat mode, the ANEX0 and ANEX1 pins can be used as analog input pins. The
OPA1 and OPA0 bits in the AD0CON1 register select which pins to use as analog input pins. An A/D
conversion result for the ANEX0 pin is stored into the AD00 register. The result for the ANEX1 pin is
stored into the AD01 register, but is stored into the AD00 register when the DUS bit in the AD0CON3
register is set to "1" (DMAC operating mode enabled).
17.2.6 External Operating Amplifier (Op-Amp) Connection Mode
In external op-amp connection mode, multiple analog voltage can be amplified by one external op-amp
using extended analog input pins ANEX0 and ANEX1.
When the OPA1 and OPA0 bits in the AD0CON1 register are set to "112" (external op-amp connection),
voltage applied to the AN0 to AN7 pins are output from ANEX0. Amplify this output signal by an external
op-amp and apply it to ANEX1.
Analog voltage applied to ANEX1 is converted to a digital code and the A/D conversion result is stored
into the corresponding AD0j register (j=0 to 7). A/D conversion rate varies depending on the response of
the external op-amp. The ANEX0 pin cannot be connected to the ANEX1 pin directly.
Figure 17.7 shows an example of an external op-amp connection.
Table 17.10 Extended Analog Input Pin Settings
AD0CON1 Register
ANEX0 Function
OPA1 Bit OPA0 Bit
0
0
Not used
0
1
P95 as an analog input
1
0
Not used
1
1
Output to an external op-amp
ANEX1 Function
Not used
Not used
P96 as an analog input
Input from an external op-amp
Analog
input
AN0
AN1
AN2
AN3
AN4
AN5
AN6
AN7
ANEX0
External op-amp
ANEX1
Figure 17.7 External Op-Amp Connection
Resistor ladder
Successive conversion register
Comparator 0
Rev. 1.00 Nov. 01, 2005 Page 233 of 330
REJ09B0271-0100