© Microhard Systems Inc.
18
3.0 Hardware Description
3.2 High Speed Interface
The special high speed interface is used for the communication between the user device and the
Turbo version of the Nano Series (n920T). This interface is a high speed clocked synchronous
channel that supports serial data to and from a modem. The Nano acts as a slave and the user’s
device acts as the master, meaning the user’s device
must
supply the clock signal. The important
feature of this interface is the use of hardware handshaking.
Technical Specifications
Type of serial channel
Clocked synchronous
Modem’s serial mode
Slave
Type of data communication
Packets
Maximum data packet size
1558 bytes
Maximum serial link rate
Up to 3.2 Mbps*
Delay from bit transition to the rising edge of clock
Less than 1/2 clock period
Table 3-3: Nano Turbo High Speed Interface Technical Specifications
Pin Name
No. Description
In/
Out
Serial RxD
44
Serial data from modem to user device
O
Serial TxD
42
Serial data to modem from user device
I
USR_SCK
50
Clock signal from user device to modem
I
CTS
32
Clear To Send. Used for handshaking purposes.
O
RING
38
Signal used for the initiation of data transfer from modem to user device. O
Table 3-2: Nano Turbo High Speed Interface Signals
On the following pages, timing diagrams show examples of the flow of data between a users device
and the Nano Series.
User’s device
must
supply the
clock signal while RING is low.
