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CHAPTER 18 8/10-BIT A/D CONVERTER
18.1
Outline of the 8/10-Bit A/D Converter
Using the RC-type successive approximation conversion method, the 8/10-bit A/D
converter converts an analog input voltage into a 10-bit or 8-bit digital value. An input
signal is selected from fifteen channels for analog input pins. The conversion can be
activated by software, 16-bit reload timer 1 output, and external trigger.
■ Functions of the 8/10-bit A/D Converter
The converter converts the analog voltage input to an analog input pin (input voltage) to a digital value.
The converter has the following features:
• The minimum conversion time is 4.9 μs (only possible at certain machine clock frequencies; includes
the sampling time).
• The minimum sampling time is 1.6 μs (only possible at certain machine clock frequencies).
• The converter uses the RC-type successive approximation conversion method with a sample hold
circuit.
• A resolution of 10 bits or 8 bits can be selected.
• Up to 15 channels for analog input pins can be selected by a program.
• At the end of A/D conversion, an interrupt request can be generated and EI
• In the interrupt-enabled state, the conversion data protection function prevents any part of the data from
being lost through continuous conversion.
• The conversion can be activated by software, 16-bit reload timer 1 (rising edge), and external trigger
ADTG.
• The MB90390 series has 15 analog inputs, where from either channels 0 to 7 or channels 8 to 14 can be
selected as inputs for the A/D converter.
Table 18.1-1 8/10-bit A/D Converter Conversion Modes
Single conversion mode
Continuous conversion
mode
Stop conversion mode
280
Single conversion
Converts the input of a specified
channel (single channel) just once.
Converts the input of a specified
channel (single channel) repeatedly.
Converts the input of a specified
channel (single channel), after which
it is on standby for the next activation.
2
Scan conversion
Converts the inputs of two or more consecutive
channels (up to eight channels) just once. Either
channel 0 to channel 7 or channel 8 to channel 14
can be selected.
Converts the inputs of two or more consecutive
channels (up to eight channels) repeatedly.Either
channel 0 to channel 7 or channel 8 to channel 14
can be selected.
Converts the inputs of two or more consecutive
channels (up to eight channels). Either channel 0 to
channel 7 or channel 8 to channel 14 can be
selected.
When a channel has been converted, the converter is
put on standby for the next activation.
OS can be activated.
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