mt9094apr1 Zarlink Semiconductor, mt9094apr1 Datasheet - Page 13

• Manufacturer Part Number: mt9094apr1
• Description: Fully Featured Digital Telephone Circuit With Embedded Dsp For Tone Generation And Hands Free Operation
• Manufacturer: Zarlink Semiconductor

Watchdog
To maintain program integrity an on-chip watchdog timer is provided for connection to the microcontroller reset pin.
The watchdog output WD (pin 17) goes high while the DPhone-II is held in reset via the PWRST (pin 6). Release of
PWRST will cause WD to return low immediately and will also start the watchdog timer. The watchdog timer is
clocked on the falling edge of F0i and requires only this input, along with V
If the watchdog reset word is written to the watchdog register (address 11h) after PWRST is released, but before
the timeout period (T=512mSec) expires, a reset of the timer results and WD will remain low. Thereafter, if the reset
word is loaded correctly at intervals less than 'T' then WD will continue low. The first break from this routine, in
which the watchdog register is not written to within the correct interval or it is written to with incorrect data, will result
in a high going WD output after the current interval 'T' expires. WD will then toggle at this rate until the watchdog
register is again written to correctly.
DPhone-II Register Map
F0i
DSTi,
DSTo
Address
17-1C
00-09
(Hex)
0A
0D
0B
0C
0E
0F
10
11
12
13
14
15
16
Used
Not
FCODEC GAIN CONTROL REGISTER 1
FCODEC GAIN CONTROL REGISTER 2
LCD SEGMENT ENABLE REGISTER 1
LCD SEGMENT ENABLE REGISTER 2
TRANSDUCER CONTROL REGISTER
C-CHANNEL REGISTER (to DSTo)
GENERAL CONTROL REGISTER
TIMING CONTROL REGISTER
CHANNEL 1
C-channel
LOOP-BACK REGISTER
WATCHDOG REGISTER
5-BIT WATCHDOG RESET WORD
x=don’t care
MSB first for C, B1 - & B2-
X
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
WRITE
Figure 6 - ST-BUS Channel Assignment
CHANNEL 2
B1-channel
Channels
X
Zarlink Semiconductor Inc.
X
MT9094
CHANNEL 3
B2-channel
W4
125 µs
0
13
W3
1
CHANNELS 4 - 31
W2
0
Not Used
C-CHANNEL REGISTER (from DSTi)
W1
1
DD
, for operation.
W0
0
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
NOT USED
VERIFY
VERIFY
VERIFY
VERIFY
VERIFY
VERIFY
VERIFY
VERIFY
READ
Data Sheet