UPD78F9234MC-5A4-A Datasheet, PDF (168/419 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

CHAPTER 10 A/D CONVERTER
(5) Successive approximation register (SAR)
This register compares the sampled analog voltage and the voltage of the D/A converter, and converts the result,
starting from the most significant bit (MSB).
When the voltage value is converted into a digital value down to the least significant bit (LSB) (end of A/D
conversion), the contents of the SAR register are transferred to the A/D conversion result register (ADCR).
(6) 10-bit A/D conversion result register (ADCR)
The result of A/D conversion is loaded from the successive approximation register to this register each time A/D
conversion is completed, and the ADCR register holds the result of A/D conversion in its lower 10 bits (the higher
6 bits are fixed to 0).
(7) 8-bit A/D conversion result register (ADCRH)
The result of A/D conversion is loaded from the successive approximation register to this register each time A/D
conversion is completed, and the ADCRH register holds the result of A/D conversion in its higher 8 bits.
(8) Controller
When A/D conversion has been completed, INTAD is generated.
(9) AVREF pin
This pin inputs an analog power/reference voltage to the A/D converter. When the A/D converter is not used,
connect this pin to VDD.
The signal input to ANI0 to ANI3 is converted into a digital signal, based on the voltage applied across AVREF and
AVSS.
(10) AVSS pin
This is the ground potential pin of the A/D converter. Always use this pin at the same potential as that of the VSS
pin even when the A/D converter is not used.
(11) A/D converter mode register (ADM)
This register is used to set the conversion time of the analog input signal to be converted, and to start or stop the
conversion operation.
(12) Analog input channel specification register (ADS)
This register is used to specify the port that inputs the analog voltage to be converted into a digital signal.
(13) Port mode control register 2 (PMC2)
This register is used when the P20/ANI0 to P23/ANI3 pins are used as the analog input pins of the A/D converter.
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User’s Manual U17446EJ5V0UD