User's Manual

User Manual
SM3000 OEM module
This is illustrated in the following diagram:
At the moment the RTS is pulled low the module is either sleeping or active. When active the module is most
probably busy with wireless communication during which it will not respond to the RTS event. Only after
finishing wireless communication will it acknowledge any pending communication requests. By this the
module's response time can be quite significant. Refer to Section Timing for T
A
(module response time) . If
the module does not respond within the given time the host should retry communication by generating a
new downward flank on the RTS line.
After the module lowered its CTS line it starts timing the reception of a full message. The host has
T
B
(module receive time) to complete sending the message after the CTS was lowered. Failure to do so will
make the module raise its CTS line before the end of the message and the host should retry communication
by generating a new downward flank on the RTS line
SM3000 to Host transmission
If the module has data to send it will pull down its DSR line. It then waits for the host to lower its DTR line.
When a low DTR is detected the module starts transmitting the message. As soon as the message is
completed the DSR line is raised. The host can raise the DTR as soon as it received the complete message or
detected the DSR being pulled high.
This is illustrated in the following diagram:
17/27 Ambient Systems B.V.