35
Interface Signals
The Modem will communicate with the host through an interface with the following
signals:
Bus
Pin
Interface Function
Signal
direction
µC*
µC Function
1 RTS
Or Data Out SPI (
1
)
O RTS
!
Request To Send
Data Out SPI
!
Data out during the programming of the Flash
Program.
2 Ack_Tx
Or Clock In SPI (
1
)
I/O Ack_Tx
!
Transmission Ok
Clock In SPI
!
Clock In during the programming of the Flash
Program.
3 N.U.
-
-
4
RXD
I
RxD UART - Serial Data Reception
5 CTS
Or Data In SPI (
1
)
I CTS
!
Clear To Send
Data In SPI
!
Data In during the programming of the Flash
Program.
6
TXD
O
TxD UART - Serial Data Transmission
7
VDD
-
5 volts power for digital ("noisy").
8
LOCK
O
Network Synchronization Ok.
9
RESET
I
External Reset. Also used during the programming of the Flash
Program.
10 GND
-
Ground
11 N.U.
I
-
12 N.U.
I
-
13 N.U.
I
-
14 N.U.
I
-
((
1
): SPI hardware only in slave. The user is connected to this bus only in Flash/EEPROM
Programming: In this case, the RESET signal has to be on.
*I = Input O = Output
NOTE: The connector used is the 14FMS-1.0SP-TF 14-pin manufactured and distributed by
JST.
