M16C30L Datasheet, PDF(136/166 Page) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

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M16C30L Datasheet, PDF (136/166 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

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A-D Converter

Mitsubishi microcomputers

M16C / 30L Group

SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

(a) Sample and hold

Sample and hold is selected by setting bit 0 of the A-D control register 2 (address 03D416) to â1â. When

sample and hold is selected, the rate of conversion of each pin increases. As a result, a 28 ÏAD cycle is

achieved with 8-bit resolution and 33 ÏAD with 10-bit resolution. Sample and hold can be selected in all

modes. However, in all modes, be sure to specify before starting A-D conversion whether sample and

hold is to be used.

(b) Extended analog input pins

In one-shot mode and repeat mode, the input via the extended analog input pins ANEX0 and ANEX1 can

also be converted from analog to digital.

When bit 6 of the A-D control register 1 (address 03D716) is â1â and bit 7 is â0â, input via ANEX0 is

converted from analog to digital. The result of conversion is stored in A-D register 0.

When bit 6 of the A-D control register 1 (address 03D716) is â0â and bit 7 is â1â, input via ANEX1 is

converted from analog to digital. The result of conversion is stored in A-D register 1.

In this mode, multiple external analog inputs via the extended analog input pins, ANEX0 and ANEX1, can

be amplified together by just one operation amp and used as the input for A-D conversion.

When bit 6 of the A-D control register 1 (address 03D716) is â1â and bit 7 is â1â, input via AN0 to AN7 is

output from ANEX0. The input from ANEX1 is converted from analog to digital and the result stored in the

corresponding A-D register. The speed of A-D conversion depends on the response of the external op-

eration amp. Do not connect the ANEX0 and ANEX1 pins directly. Figure 1.17.5 is an example of how to

connect the pins in external operation amp mode.

Resistor ladder

Analog

input

AN0

AN1

AN2

AN3

AN4

AN5

AN6

AN7

Successive conversion register

ANEX0

ANEX1

External op-amp

Comparator

Figure 1.17.5. Example of external op-amp connection mode

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