Aug.2007

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Special Function Register (SFR)

Special function register area is during the addresses from $00H to $22H. These special function

registers control all I/O and timer function setting. Some of memory addresses are not defined and

un-used. It is unnecessary for the users to read or write data from these undefined areas. User should

follow the default value or do not access these undefined area. All its functions are listed in next

sections.

Interrupt and Timers

Address

00H

Bit7

Bit6

Bit5

Bit4

Bit3

Bit2

Bit1

Bit0

NAME INTEN

ADINT

#

#

T1INT

T0INT

PBINT

TBINT

RTCINT

Read or Write

R/W

#

#

R/W

R/W

R/W

R/W

R/W

Default Value

0

#

#

0

0

0

0

0

The EU101x builds in 8 interrupt sources: Real Time Clock interrupt, Time Base interrupt, PB input ports

falling edge interrupt, Timer0 underflow interrupt, Timer1 underflow interrupt, A/D converter interrupt and

RESET interrupt. By setting control register INTEN (00H) that can enable or disable corresponding

interrupt sources. Interrupt source, interrupt vector address mapping and its priority are shown in the

following table.

Address

Interrupt Source

Priority

3FFF0H/3FF1H

ADC interrupt

7

3FF2H/3FF3H

Timer1 interrupt

6

3FF4H/3FF5H

Timer0 interrupt

5

3FF6H/3FF7H

PB port interrupt

4

3FF8H/3FF9H

Time base interrupt

3

3FFAH/3FFBH

RTC interrupt

2

3FFCH/3FFDH

Reset

1

3FFEH/3FFFH

Reserved

0

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