M32CSLASH86 datasheet(274/505 Pages) RENESAS

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18. A/D Converter

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18.2.5 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

Set the APS1 and APS0 bits in the AD0CON2 register to "002" (AN0 to AN7, ANEX0, ANEX1) and the

MSS bit in the AD0CON3 register to "0" (multi-port sweep mode disabled).

18.2.6 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.

Set the APS1 and APS0 bits in the AD0CON2 register to "002" (AN0 to AN7, ANEX0, ANEX1).

Figure 18.7 shows an example of an external op-amp connection.

Table 18.10 Extended Analog Input Pin Settings

AD0CON1 Register

ANEX0 Function

ANEX1 Function

OPA1 Bit

OPA0 Bit

Not used

P95 as an analog input

Not used

P96 as an analog input

Output to an external op-amp

Input from an external op-amp

AN0

AN7

AN1

AN2

AN3

AN4

AN5

AN6

ANEX1

ANEX0

Resistor ladder

Successive conversion register

Analog

input

External op-amp

Comparator 0

002

APS1 and APS0 bits

in AD0CON2 register

Figure 18.7 External Op-Amp Connection

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