W78E516B

- 6 -

to clear the B7 bit of security register. Once B7 is set to 0, a half of gain will be decreased. Care must

be taken if user attempts to diminish the gain of oscillator amplifier, reducing a half of gain may affect

the external crystal operating improperly at high frequency above 24 MHz. The value of R and C1, C2

may need some adjustment while running at lower gain.

Reset

The external RESET signal is sampled at S5P2. To take effect, it must be held high for at least two

machine cycles while the oscillator is running. An internal trigger circuit in the reset line is used to

deglitch the reset line when the W78E516B is used with an external RC network. The reset logic also

has a special glitch removal circuit that ignores glitches on the reset line. During reset, the ports are

initialized to FFH, the stack pointer to 07H, PCON (with the exception of bit 4) to 00H, and all of the

other SFR registers except SBUF to 00H. SBUF is not reset.

W78E516B Special Function Registers (SFRs) and Reset Values

F8

FF

F0

+B

00000000

CHPENR

00000000

F7

E8

EF

E0

+ACC

00000000

E7

D8

+P4

xxxx1111

DF

D0

+PSW

00000000

D7

C8

+T2CON

00000000

RCAP2L

00000000

RCAP2H

00000000

TL2

00000000

TH2

00000000

CF

C0

XICON

00000000

SFRAL

00000000

SFRAH

00000000

SFRFD

00000000

SFRCN

00000000

C7

B8

+IP

00000000

CHPCON

0xx00000

BF

B0

+P3

00000000

B7

A8

+IE

00000000

AF

A0

+P2

11111111

A7

98

+SCON

00000000

SBUF

xxxxxxxx

9F

90

+P1

11111111

97

88

+TCON

00000000

TMOD

00000000

TL0

00000000

TL1

00000000

TH0

00000000

TH1

00000000

8F

80

+P0

11111111

SP

00000111

DPL

00000000

DPH

00000000

PCON

00110000

87

Notes:

1.The SFRs marked with a plus sign(+) are both byte- and bit-addressable.

2. The text of SFR with bold type characters are extension function registers.