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A-D CONVERTER

7906 Group User’s Manual Rev.2.0

12-31

[Precautions for A-D converter]

1. Be sure to clear the VREF connection select bit to “0.”

2. Writing to the following must be performed before a trigger is generated (in other words, while the A-D

converter halts); this must be done independent of the operation mode of the A-D converter.

• Each bit of the A-D control register 0, except bit 6

• Each bit of the A-D control register 1

• A-D register i (when the comparator function is selected)

• Comparator function select register 0

• Comparator result register 0

Especially, when any instruction which clears the VREF connection select bit from “1” to “0” has been

executed (in other words, the resistor ladder network is connected with pin VREF by this instruction), an

interval of 1

µs or more must be elapsed before occurrence of a trigger.

3. Reading from A-D register i (when the comparator function is selected) must be performed before occurrence

of a trigger (in other words, while the A-D converter halts.). The value undefined at reading.

4. When using pin AN3, be sure that the D-A0 output enable bit (bit 0 at address 9616) = “0” (output disabled).

When using pin AN4, be sure that the D-A1 output enable bit (bit 1 at address 9616) = “0” (output disabled).

5. Note that the operation time for pins AN0 to AN4 is equivalent to the time for 6 pins when the A-D sweep

pin select bits (bits 1, 0 at address 1F16) = “102” in the single sweep mode and repeat sweep mode 0.

6. Refer to section “Appendix. 7 Countermeasures against noise” when using the A-D converter.

7906 Datasheet(PDF) 326 Page - Renesas Technology Corp