Serial I/O - Motorola Symbol MS4404 Integration Manual

1 - 6 Symbol MS4404/MS4407 Integration Guide
Waking the Symbol MS4404
Table 1-2
Signal
AIM/WKUP*
TRIG*
CTS*
RXD
When the Symbol MS4404 wakes, it remains awake for at least 1 second (programmable time) before re-entering
Low Power mode. The host must perform its first action within this time period.

Serial I/O

Simple Serial Interface (SSI) Protocol is a half-duplex asynchronous serial interface with two hardware handshaking
lines. The four SSI-specific interface signals are:
•
TXD - Transmitted Data
•
RXD - Received Data
•
RTS* - Request to Send
CTS* - Clear to Send
•
Signal names with the "*" modifier are asserted when at the positive logic 0 state (active low).
Signal names without the "*" modifier are asserted when at the positive logic 1 state (active high).
The TXD line transmits asynchronous serial data from the Symbol MS440X to the host.
The Symbol MS440X uses the RXD line to receive asynchronous serial data from the host. The SSI protocol does
not support full-duplex data transfers. The Symbol MS440X either transmits or receives data, but never both
simultaneously.
The RTS* and CTS* signals help coordinate data transfers between the Symbol MS440X and the host.
State to Wake Up
Low
Low
Low
Send 0x00