TP3420A National Semiconductor, TP3420A Datasheet - Page 30

• Manufacturer Part Number: TP3420A
• Description: ISDN S/T Interface Device
• Manufacturer: National Semiconductor

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0 (MFC INT)
5
10
15
20
25
0 (MFC INT)
5
10
15
20
25
0 (MFC INT)
5
10
15
20
25
0 (MFC INT)
5
10
15
20
25
0 (MFC INT)
SC1 Messaging Sequence
On the TE receive side, the LP, DTSE and FECV messages
are checked once, and for every occurrence an interrupt
is generated. The other messages are validated 3 times be-
fore an interrupt is generated. Subsequent repetitions of the
command do not cause an interrupt.
SC2 CHANNEL TRANSMITTER HANDLING
The software should keep a list of flags to indicate SC2 com-
mands as defined in the spec. At the 30 ms tick MFC INT, the
software should scan through the list of flags (top down) and,
Time
(ms)
I430 Frame Content
(IDLE)
(IDLE)
(IDLE)
(IDLE)
(IDLE)
(IDLE)
(IDLE)
(LB1I)
(LB1I)
(LB1I)
(LB1I)
(LB1I)
(LB1I)
(LB2I)
(LB2I)
(LB2I)
(LB2I)
(LB2I)
(LB2I)
(LRS)
(LRS)
(LRS)
(LRS)
(LRS)
(LRS)
SC1
(Continued)
if FL__EXT flag set, do not check for new flags on SC1L, but check for
SC2 channel. Reset FL__EXT. Send SC2 command as appropriate.
SC1L__NB (IDLE)
if FL__EXT flag not set, check for new flags on SC1L, assume LB1I.
Check for SC2 channel. Send SC2 command as appropriate.
SC1__NB(IDLE)
SC1__NB(LB1I)
if FL__EXT flag not set, Check for new flags on SC1L assume LB2I.
Check for SC2 channel. Send SC2 command as appropriate.
SC1__NB(LB1I)
SC1__NB(LB2I)
if FL__EXT flag not set, check for new flags on SC1L, assume IDLE.
Check for SC2 channel. Send SC2 command as appropriate.
SC1__NB(LB2I)
SC1__ NB(IDLE)
etc.
30
seeing the first flag, should write the appropriate command
in the MFT2 register and keep the value in SC2__NB (soft-
ware buffer).
On the TE receive side, the SC2 command is verified 3
times before an Interrupt is generated. Subsequent repeti-
tions of the command do not cause an interrupt.
>
>
>
>
>
>
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MFT1L.
SC1__PB, SC1 command(LB2I)
MFT1L
SC1__PB, SC1 command (IDLE)
SC1__PB, SC1 command (LBL1I)
MFT1L.
MFT1L
Actions Required
>
>
>
SC1__NB,
SC1__NB
SC1__NB,