Chapter 16
A/D Converter (ADC)
XVI - 8 Operation
16.3 Operation
The following shows the procedures for setting ADC circuit.
1. Set the analog input terminal.
Set the analog input terminal by ANEN0.
* Be sure to set Analog input control register before applying analog voltage to the terminals.
2. Select the analog input terminal.
Select the analog input pin from AN7 to AN0 by setting the ANCTR1.ANCHS2 to 0.
3. Select the A/D conversion clock.
Select the A/D conversion clock by setting the ANCTR0.ANCK2-0. Set the conversion clock (T
ADCLK
)
between 750 ns and 100
µs depending on the resonator to be used.
4. Set the sample hold time.
Set the sample hold time by the ANCTR0.ANSH1-0.
Select the appropriate value based on the analog impedance.
* The steps of (2) to (4) can be performed in random order. The steps of (3) and (4) can be
operated simultaneously.
5. Set the A/D resistor ladder.
Set the ANCTR0.ANLADE to "1" to apply current to the resistor ladder so that ADC will be in standby condi-
tion.
6. Select the ADC activation factor, then start A/D conversion.
Set the ANCTR2.ANST to "1" to enable the ADC or set the ANCTR2.ANSTSEL1-0 to "01" or "10" to enable
the ADC by external trigger factor.
7. A/D conversion.
A/D conversion is compared and determined sequentially by MSB after the sampling in the sample hold time
(which is set in the step (4)).
8. Complete A/D conversion.
After A/D conversion is completed, the result of the conversion is stored in ANBUF0 and ANBUF1, A/D con-
version interrupt is generated and the ANCTR2.ANST is cleared to "0".
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