upd70f3017ay Renesas Electronics Corporation., upd70f3017ay Datasheet - Page 316

• Manufacturer Part Number: upd70f3017ay
• Description: V850/sa1tm 32-/16-bit Single-chip Microcontroller
• Manufacturer: Renesas Electronics Corporation.

11.4 Operation
11.4.1 Basic operation
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<1> Select one channel whose analog signal is to be converted into a digital signal by using the analog input
<2> The sample & hold circuit samples the voltage input to the selected analog input channel.
<3> After sampling for a specific time, the sample & hold circuit enters the hold status, and holds the input analog
<4> Set bit 9 of the successive approximation register (SAR). The tap selector sets the voltage tap of the series
<5> The voltage difference between the voltage tap of the series resistor string and the analog input voltage is
<6> Next, bit 8 of the SAR is automatically set, and the analog input voltage is compared again. Depending on
<7> The above steps are repeated until bit 0 of the SAR has been manipulated.
<8> When comparison of all 10 bits of the SAR has been completed, the valid digital value remains in the SAR,
Caution The first conversion value immediately after setting ADCS = 0 → 1 may not satisfy the ratings.
channel specification register (ADS).
voltage until it has been converted into a digital signal.
resistor string to (1/2) AV
compared by the voltage comparator. If the analog input voltage is greater than (1/2) AV
SAR remains set. If the analog input voltage is less than (1/2) AV
the value of bit 9 to which the result of the preceding comparison has been set, the voltage tap of the series
resistor string is selected as follows:
•
•
The analog input voltage is compared with one of these voltage taps, and bit 8 of the SAR is manipulated as
follows depending on the result of the comparison.
•
•
and the value of the SAR is transferred and latched to the A/D conversion result register (ADCR).
At the same time, an A/D conversion end interrupt request (INTAD) can be generated.
Bit 9 = 1: (3/4) AV
Bit 9 = 0: (1/4) AV
Analog input voltage ≥ voltage tap: Bit 8 = 1
Analog input voltage ≤ voltage tap: Bit 8 = 0
REF
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REF
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CHAPTER 11 A/D CONVERTER
User’s Manual U12768EJ4V1UD
REF
, the MSB is reset.
REF
, the MSB of the