3886 datasheet(243/380 Pages) RENESAS

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3886 Group User’s Manual

APPLICATION

2.8 D-A Converter

2-126

When the registers are set as shown in Figure 2.8.7, the speaker output volume is modulated by the

D-A output value. Figure 2.8.8 shows the control procedure.

Fig. 2.8.8 Control procedure

RESET

Initialization

SEI

CLT (Note 1)

CLD (Note 2)

ICON1

P5D

ADCON

PREX

WORK flag (Note 3)

IREQ1

ICON1

DA1

CLI

2 – 1

D616 – 1

Main processing

Value of WORK flag ?

“1”

“0”

RTI

(address 3E16), bit4

(address 0B16), bit6

(address 3416)

(address 2316)

(address 2416)

(address 2516)

(address 3C16), bit4

(address 3E16), bit4

(address 3616)

(address 2316)

Timer X interrupt process routine

Pop registers

X1XXXXXX2

•All interrupts disabled

•Timer X interrupt disabled

•Set port P56 to input mode

•DA1 output enabled

•Timer Y: Timer mode, Timer X count: Stop

•Set “division ratio – 1” to Prescaler X

•Set “division ratio – 1” to Timer X

•Timer X interrupt request bit cleared

•Timer X interrupt: Enabled

•D-A converter start

•All interrupts enabled

•Timer X count start

Notes 1: When using Index X mode flag

2: When using Decimal mode flag

3: The WORK flag is a user flag for work. When this flag is

“1”, a value other than Vss is output from the DA output

pin. When this flag is “0”, Vss is output from the DA output

pin.

•Push registers used in interrupt process routine

•Pop registers pushed to stack

q x: This bit is not used here. Set it to “0” or “1” arbitrarily.

XX001XXX2

Set output value (volume)

XX000XXX2

Push registers to stack

Set value except Vss to D-A1 conversion

Set “0” to WORK flag.

Set value of Vss to D-A1 conversion register.

Set “1” to WORK flag.

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