as2578 austriamicrosystems, as2578 Datasheet - Page 4

• Manufacturer Part Number: as2578
• Description: Telephone Controller With 13 Memories And 2-wire Bus
• Manufacturer: austriamicrosystems

Data Sheet
Valid Keys
The keyscanning is enabled when CE or HS are high.
During setup the keyboard is disabled. A valid key is
detected from the keyboard by connecting the appropriate
row to the column. This can be done using an n x m
keyboard matrix with single contacts. Positive and
negative edges of each contact are debounced. The
debounce time is 15 ms.
Mute Key
The mute key is only enabled when off-hook. Depressing
the mute key activates and deactivates (toggle switch)
the MUTE output, when internal mute is inactive, i.e. in
speech mode.
Any key entry overwrites a mute activated by the mute
key, and mute will be deactivated.
Centrex Keys (AS2578B only)
The alphameric keys accommodate easy use of centrex
services. The A, B, C and D keys are only valid in MF
mode and are not storable. Pressing one of these keys
will invoke the appropriate MF tones to be transmitted.
The centrex keys are not stored in the RAM, but are
buffered in the FIFO, and subsequently entered digits
are also buffered in the FIFO.
Pressing the recall key after a sequence including centrex
keys will reset the RAM counter, and subsequently
entered digits will be stored in the RAM. If MF select (Set,
* , Set) has been invoked once, then all susequently
digits/data will be buffered in the FIFO.
Memory Keys
The keys M1 to M3 are direct memory access keys and
the MEM key is used for abbreviated dialling.
13 numbers can be stored in on chip RAM. Each number
can contain up to 20 digits (including pauses).
If an EEPROM is connected to the serial bus, the content
of the RAM is written into the EEPROM when CE is
turned low indicating a power loss.
During programming multible pauses can be inserted by
pressing the LNR key.
Memory dialling is cascadable.
Mode Selection
The default mode (LD or MF) can be selected by the
MODE pin.
Rev. 3
4
Furthermore, the mode can be selected by setting the
LM code (see setup menu). If no LM code is set, the
mode will be determined by the MODE pin.
When default LD mode is selected, a temporary change
to MF mode can be invoked by pressing * (AP = high,
AS2578 only) or Set, * , Set.
When the circuit is in temporary MF mode, each of the
following procedures revert it to default LD mode:
- pressing Set, * , Set ,
- pressing recall key (by further entries of the recall key
- by next On-hook.
Last Number Redial
LNR is a facility that allows resignalling of the last
manually dialled number without keying in all the digits
again. The LNR is repeatable.
The current contents of the RAM are overwritten by new
entries.
A manually entered number is automatically stored in the
LNR RAM. The capacity of the RAM is 30 digits. If a
number greater than 30 digits is entered, the LNR facility
will be inhibited (until new entries < 31 digits) and further
entries will be buffered in FIFO.
Postdialled digits, i.e. digits manually entered after LNR
has been invoked, are not stored in RAM but buffered in
FIFO.
Recall Function
A recall activation will invoke a flash (timed loop break)
or a ground loop (GL) depending on the selected LM
code, which is stored in the external EEPROM (see
setup menu).
If no LM code is set, depressing the recall key will invoke
both a flash and a GL, however, in LD mode a Flash is
never executed.
If recall is the first entry in a digit string, it will be stored
If the recall key is depressed after a digit string has been
entered or dialled out, the recall will not be stored, and
subsequently entered digits will be stored in the LNR
RAM as the new number.
If pressing the recall key is not followed by digit entries,
the LNR RAM remains intact.
in LNR RAM when digit(s) are entered after the recall.
the signalling mode will toggle between MF and LD,
AS2578 /B
March 1997