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Chapter 15
A/D Converter
Preliminary User’s Manual U15839EE1V0UM00
15.2 Configuration
The A/D converter, which employs a successive approximation technique, performs A/D conversion
operation using A/D converter mode register ADM, A/D converter register ADS and A/D conversion
result registers ADCRL/ADCRH.
The A/D converter consists of the following hardware.
Table 15-1:
A/D Converter Configuration
(1)
Input circuit
The input circuit selects an analog input channel (ANIm) according to the mode set in the ADM
register and sends it to the sample and hold circuit (m = 0 to 11).
(2)
Sample and hold circuit
The sample and hold circuit samples the analog input sent from the input circuit and sends it to the
comparator. It holds the sampled analog input during A/D conversion.
(3)
Voltage comparator
The voltage comparator compares the analog input voltage from the input with the output voltage
of the D/A converter.
(4)
D/A converter
The D/A converter is used to generate a voltage that matches an analog input.
The output voltage of the D/A converter is controlled by the successive approximation register
(SAR).
(5)
Successive approximation register (SAR)
The SAR is a 10-bit register that controls the output value of the D/A converter for comparing with
an analog input voltage value. When an A/D conversion terminates, the current contents of the
SAR (conversion result) are stored in the A/D conversion result register (ADCR/ADCRL/ADCRH).
When the specified A/D conversion terminates, there also is an A/D conversion termination inter-
rupt (INTAD).
Item
Configuration
Analog input
12 channels (ANI0 to ANI11)
Register
Successive approximation register (SAR)
A/D conversion result register (ADCR)
A/D conversion result register (ADCRL): only lower
2-bits of A/D conversion result can be read
A/D conversion result register (ADCRH): only higher
8-bits of A/D conversion result can be read
Control register
A/D converter mode register (ADM)
Analog input channel setting register (ADS)
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