Configuration - NEC V850ES/F 3-L Series User Manual

A/D Converter (ADC)

19.2 Configuration

Table 19-1
Item Configuration
Analog inputs ANI0 to ANIm
Registers Successive approximation register (SAR)
A/D conversion result registers ADAnCRm, ADAnCRmH
AVREF A/D conversion diagnostic registers ADAnCRDD, ADAnCRDDH
AVSS A/D conversion diagnostic registers ADAnCRSS, ADAnCRSSH
ADC power-fail compare mode register ADAnPFM
ADC power-fail compare threshold value register ADAnPFT
Control registers A/D Converter mode registers 0 to 2 (ADAnM0 to ADAnM2)
A/D Converter channel specification register 0 (ADAnS)
(1)
(2)
Caution
(3)
The A/D Converter includes the following hardware.
Configuration of A/D Converter
SAR - Successive approximation register
The SAR register compares the voltage value of the analog input signal with
the voltage tap (compare voltage) value from the series resistor string, and
holds the comparison result starting from the most significant bit (MSB).
When the comparison result has been held down to the least significant bit
(LSB) (i.e., when A/D conversion is complete), the contents of the SAR register
are transferred to the ADAnCRm register.
A/D conversion result register n (ADAnCRm), A/D conversion result
register nH (ADAnCRmH)
The ADAnCRm register is a 16-bit register that stores the A/D conversion
result. ADAnCRm consist of m registers and the A/D conversion result is
stored in the 10 higher bits of the ADAnCRm register corresponding to analog
input. (The lower 6 bits are fixed to 0.)
The ADAnCRm register is read-only, in 16-bit units.
When using only the higher 8 bits of the A/D conversion result, the
ADAnCRmH register is read-only, in 8-bit units.
A write operation to the ADAnM0 and ADAnS registers may cause the contents
of the ADAnCRm register to become undefined. After the conversion, read the
conversion result before writing to the ADAnM0 and ADAnS registers. Correct
conversion results may not be read if a sequence other than the above is used.
Power-fail compare threshold value register (ADAnPFT)
The ADAnPFT register sets a threshold value that is compared with the value
of A/D conversion result register nH (ADAnCRmH). The 8-bit data set to the
ADAnPFT register is compared with the higher 8 bits of the A/D conversion
result register (ADAnCRmH).
This register can be read or written in 8-bit or 1-bit units.
Reset input clears this register to 00H.
User's Manual U18743EE1V2UM00
Chapter 19
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