M16C62N Datasheet, PDF (137/213 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

A-D Converter
Mitsubishi microcomputers
M16C / 62N Group (80-pin)
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 “1”. When
sample and hold is selected, the rate of conversion of each pin increases. As a result, a 28 φAD cycle is
achieved with 8-bit resolution and 33 φAD 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 “1” and bit 7 is “0”, 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 “0” and bit 7 is “1”, input via ANEX1 is
converted from analog to digital. The result of conversion is stored in A-D register 1.
Furthermore, the input via 8 pins of the extended analog input pins AN00 to AN07 can be converted from
analog to digital. These pins can be used the same as AN0 to AN7.
Use the A-D control register 2 (address 03D416) bit 1 and bit 2 to select the pin group AN0 to AN7, AN00
to AN07.
(c) External operation amp connection mode
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 “1” and bit 7 is “1”, input via AN0 to AN7 (Note)
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
operation amp. Do not connect the ANEX0 and ANEX1 pins directly. Figure 1.15.9 is an example of how
to connect the pins in external operation amp mode.
Note : AN00 to AN07 can be used the same as AN0 to AN7.
Port P10 group
Analog input pins
AN0
AN1
AN2
AN3
AN4
AN5
AN6
AN7
Port P0 group
Analog input pins
AN00
AN01
AN02
AN03
AN04
AN05
AN06
AN07
ADGSEL1,ADGSEL0
= 0,0
Resistor ladder
Successive conversion register
ADGSEL1,ADGSEL0
= 1,0
ANEX0
ANEX1
External op-amp
Figure 1.15.9. Example of external op-amp connection mode
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Comparator