Chapter 20 8/10-Bit A/D Converter; Overview Of The 8/10-Bit A/D Converter - Fujitsu MB90460 Series Hardware Manual

CHAPTER 20 8/10-BIT A/D CONVERTER

20.1

Overview 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 eight channels for analog input pins. The conversion
can be activated by software, an internal clock, and 16-bit free-run timer zero detection.
■ 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 6.13 µs (for a machine clock of 16 MHz; includes the sampling time).
• The minimum sampling time is 3.75 µs (for a machine clock of 16 MHz).
• The converter uses the RC-type successive approximation conversion method with a sample and hold
circuit.
• A resolution of 10 bits or 8 bits can be selected.
• Up to eight 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 16-bit free-run
timer zero detection edge.
Table 20.1-1 lists three types of conversion modes.
Table 20.1-1 8/10-bit A/D Converter Conversion Modes
Single conversion mode
Continuous conversion mode
Stop conversion mode
542
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
OS can be activated.
Scan conversion
Converts the inputs of two or more consecutive
channels (up to eight channels) just once.
Converts the inputs of two or more consecutive
channels (up to eight channels) repeatedly.
Converts the inputs of two or more consecutive
channels (up to eight channels).
When a channel has been converted, the
converter is put on standby for the next
activation.