ST75951 datasheet(10/21 Pages) STMICROELECTRONICS

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GPIO3

REG 2 - BIT4

SETTING

Figure 12 : GPIO3 When bit10 = ’1’ in REG2

FUNCTIONAL DESCRIPTION (continued)

F0/N

GPIO0

REG 2 - BIT1

SETTING

Figure 11 : GPIO0 When bit6 = ’1’ in REG2

GPIO1 and GPIO2 are dedicated input and control

CLID and OFF-HOOK function respectively if the

control input Pin HM is set to ’1’.

Table 2

GPIO1

GPIO2

Function

ON-HOOK

OFF-HOOK

CLID

SPECIAL

Function

ON-HOOK

OFF-HOOK

CLID

SPECIAL

CL, OH : Bit 2, 3 Reg 3.

Depending of the setting of the Mask bit in control

generate an interrupt to the processor thanks to

GPI (General purpose Interrupt).

7 - Operating Modes

Three operating modes controlled either by the

GPIO1 and 2 or by the control register 3 are imple-

mented :

- ON-HOOK,

- OFF-HOOK,

- CLID (Caller ID).

Figure 13

Figure 14

7.1 - ON-HOOK

During ON-HOOK state no signal is sent by D5, D6.

D5 = D6 = VDD.

Ring

When in ON-HOOK state, the ST952 sends a

1MHz differential signal on D3, D4 when it re-

ceives an incoming ringing signal from Tip/Ring.

ST75951 will output on RING Pin the image of the

ring signal (RING Pin is also duplicated in the read

7.2 - OFF-HOOK

Depending on Pin HM status (see Table 2), 2 pos-

sibilities are offered to control the device to go in

OFF-HOOK state.

D5 and D6 send F0 clock in opposite phase to

ST952.

ST75951

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