User's Manual

MaxStream 9XStream™ Wireless OEM Module Manual v2.8

Confidential and Proprietary, ©MaxStream, Inc. 2001

DO (Data Out) – Pin 3 (Output)

Data received from over-the-air transmissions is checked for errors and then

sent to the DO pin.

CTS – Pin 1 (Output)

The CTS pin (clear to send) informs the host device whether or not serial data

can be sent to the 9XStream module. When CTS registers as low, serial data

can be sent to the 9XStream module. All incoming serial data is stored in a

data buffer until the next data packet is transmitted (over-the-air). The data

buffer can hold up to 132 bytes of data. At 115 bytes, the 9XStream module

de-asserts the CTS signal (sets it high) to alert the host device to stop sending

serial data. The CTS remains de-asserted until the number of bytes in the

buffer drops below 98.

There are three cases in which the data buffer may become full:

1. When the 9600 and 19200-baud modules are configured at a higher serial

data rate than the module’s over-the-air baud rate causing the data buffer

to become momentarily full and CTS to de-assert.

2. The 9XStream module is a half-duplex transmitter/receiver. If the module

is receiving a long, continuous string of over-the-air data, any serial data

that arrives at the buffer will not be transmitted until the module no longer

detects over-the-air data.

3. If any module in a network (see Networking and Addressing) is

transmitting data, all other modules in the network will not transmit until

they finish receiving data. If the network modules receive lengthy serial

data, their data buffers may become full.

Note: In applications where none of these conditions occur, the

CTS signal need not be monitored.