Hardware interfaces
Version 8 dated 15.03.00
20
Siemens Information and Communication Products
Table 4-3
Timing values of display interface
4.3.4
Keypad
10 Pins for 4*6 keypad matrix.
For activation of a key, connect a row signal to the appropriate column signal. The keypad address matrix implemented
in the MMI software can be found in Chapter
6.2 “Keypad address matrix” on page 142
Note
: maximum input speed: 1 key per 400ms
4.3.5
Serial Interface RS323 (V.24) Connections and signals
The Serial Interface can be used for:
• AT command interface
• Software download (SW update), see
8.5 “SW download (Version update)” on page 191
• serial interface for data/fax/SMS services.
Note
:
External level converter is necessary for V.24 level when using the M20.
The M20T has a direct 9 pin serial interface port.
Parameter
Comment
Min.
Typ.
Max.
Units
t
10
Write high byte to display enable high
152
ns
t
11
Display enable high width
462
ns
t
12
Display enable low width
462
ns
t
13
Display register select setup
10
ns
t
14
Display register select hold
5
ns
t
15
Display chipselect setup
10
ns
t
16
Display chipselect hold
5
ns
t
17
Data setup
68
ns
t
18
Data hold
15
ns
t
11a
Display enable high width read extension
538
ns
t
19
Display enable low to write high
10
ns
t
20
Display register select to display enable high
200
ns
t
21
Display chipselect to display enable high
200
ns
t
22
Display enable high to data valid
450
ns
t
23
Data hold
0
ns
Signal
Function
I/O
Level
Comments
KPR0...5
Keypad row
I
2.8 V
may be disconnected if unused
KPC0...3
Keypad column
O
2.8 V
may be disconnected if unused
