M16CSLASH29 datasheet(262/499 Pages) RENESAS

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15. A/D Converter

page 238

Item

Specification

Function

Bits SCAN1 and SCAN0 in the ADCON1 register and bits ADGSEL1 and

ADGSEL0 in the ADCON2 register select pins. Analog voltage applied

to the selected pins is converted one-by-one to a digital code. At this time,

the input voltage of AN0 and AN1 are sampled simultaneously.

A/D Conversion Start Condition

When the TRG bit in the ADCON0 register is 0 (software trigger)

Set the ADST bit in the ADCON0 register to 1 (A/D conversion started)

When the TRG bit in the ADCON0 register is 1 (hardware trigger)

The trigger is selected by bits TRG1 and HPTRG0 (See Table 15.9)

The ADTRG pin input changes state from “H” to “L” after setting the ADST

bit to 1 (A/D conversion started)

Timer B0, B2 or Timer B2 interrupt generation frequency setting counter

underflow after setting the ADST bit to 1 (A/D conversion started)

A/D Conversion Stop Condition

A/D conversion completed (If selecting software trigger, the ADST bit is

automatically set to 0 ).

Set the ADST bit to 0 (A/D conversion halted)

Interrupt Generation Timing A/D conversion completed

Analog Input Pin

Select from AN0 to AN1 (2 pins), AN0 to AN3 (4 pins), AN0 to AN5 (6 pins),

or AN0 to AN7 (8 pins) (1)

Readout of A/D conversion result Readout one of registers AN0 to AN7 that corresponds to the selected pin

NOTE:

1. AN00 to AN07, AN 20 to AN27, and AN30 to AN32 can be used in the same way as AN0 to AN7. However, all input

pins need to belong to the same group.

15.1.6 Simultaneous Sample Sweep Mode

In simultaneous sample sweep mode, analog voltages applied to the selected pins are converted one-by-

one to a digital code. The input voltages of AN0 and AN1 are sampled simultaneously using two circuits

of sample and hold circuit. Table 15.8 shows the simultaneous sample sweep mode specifications.

Figure 15.16

shows the operation example in simultaneous sample sweep mode. Figure 15.17 shows

registers ADCON0 to ADCON2 and Figure 15.18 shows ADTRGCON registers in simultaneous sample

sweep mode. Table 15.9 shows the trigger select bit setting in simultaneous sample sweep mode. In

simultaneous sample sweep mode, Timer B0 underflow can be selected as a trigger by combining soft-

___________

ware trigger, ADTRG trigger, Timer B2 underflow, Timer B2 interrupt generation frequency setting counter

underflow or A/D trigger mode of Timer B.

Figure 15.16 Operation Example in Simultaneous Sample Sweep Mode

Table 15.8 Simultaneous Sample Sweep Mode Specifications

•Example when selecting AN0 to AN3 to A/D pins for sweep (SCAN1 to SCAN0 = 012)

A/D conversion started

A/D interrupt request generated

AN0

AN1

AN2

AN3

AN4

AN5

AN6

AN7

A/D pin input voltage

sampling

A/D pin conversion

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