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This chapter explains the 8-/10-bit A/D converter functions and operation.
19.1 Overview of 8-/10-bit A/D Converter
The 8-/10-bit A/D converter converts the analog input voltage to a 10- or 8-bit digital value by using the RC
sequential-comparison converter system. An input signal can be selected from the input signals of the
analog input pins for 8 channels, and a conversion start can be selected from the trigger input starts made by
the software, 16-bit reload timer 1, and external pins.
n Function of 8-/10-bit A/D converter
The 8-/10-bit A/D converter converts the analog voltage (input voltage) input to the analog input pin to a
digital value. It has the following features:
• Conversion time: 6.13 µs min. per channel (at 16 MHz machine clock; including sampling time)
• Sampling time: 3.75 µs min. (at 16 MHz machine clock)
• RC sequential-conversion converter system with sample hold circuit
• 8-bit or 10-bit resolution selection enabled
• Analog input pin can be selected from 8 channels by program.
• At termination of A/D conversion, interrupt request can be issued and EI
• With interrupt enabled, converted data is protected, so data is not lost even at continuous conversion.
• Conversion start factor can be selected from software, external trigger input (falling edge) and 16-bit reload
timer 1 (rising edge), and zero detect edge of 16-bit free-run timer.
There are three conversion modes as shown in Table 19-1.
Conversion Mode
Single-shot
The specified channel (only one channel) is
conversion mode
converted once and terminated.
Continuous
The specified channel (only one channel) is
conversion mode
converted repeatedly.
Convert-stop mode
When the specified channel (only one channel)
is converted once and suspended to wait for the
next conversion to be started.
Interrupt No.
Register Name
#32 (20
)
H
m: Can be used
8-/10-BIT A/D CONVERTER
Table 19-1 Conversion Modes of 8-/10-bit A/D Converter
Single Conversion
Table 19-2 8-/10-bit A/D Converter Interrupt and EI
Interrupt control Register
Address
ICR10
0000BA
Sequential two or more channels (up to 8
channels) are converted once and terminated.
Sequential two or more channels (up to 8
channels) are converted repeatedly.
Sequential two or more channels (up to 8
channels) are converted.
However, every time each channel is
converted, operation is suspended to wait for
the next conversion to be started.
Address of Vector Table
Lower
FFFF7C
H
H
19-3
2
OS can be also started.
Scan Conversion
2
OS
Upper
Bank
FFFF7D
FFFF7E
H
2
EI
OS
m
H
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