User's Manual

Modes of Operation

The 24XStream wireless module features several modes of operation that allow the module to be

responsive to data and yet utilize minimum power. The figure below shows these modes and is

followed by a comprehensive look into each mode and the necessary conditions for the

24XStream module to transition from one mode to another.

Idle Mode

The 24XStream module operates in Idle Mode when there is no data being transmitted or

received. The module will transition to Transmit Mode once data is presented on the DI pin. If

valid data is detected at the antenna, the module will switch from Idle Mode to Receive Mode.

When no longer transmitting or receiving, the module returns to Idle Mode.

Transmit Mode

When the first byte arrives in the data buffer through the DI pin, the module leaves Idle Mode and

transitions to Transmit Mode. This transition happens instantaneously from the moment the first

byte of data arrives in the data buffer. In Transmit Mode, a header is sent out and is then

followed by the first data packet, which has a CRC (cyclic redundancy check) attached (see “Data

Validity” section below for more information). The first data packet contains all bytes that

accumulated in the data buffer while the header was being sent. After the first data packet is sent,

if more data is available in the buffer, another header will be sent, followed by another data

packet. This second data packet (and all subsequent data packets) will consist of data that

accumulated in the buffer while the previous data packet and header were being sent out (see

Figure 5b below). The size of each data packet can vary up to 64 bytes. This progression is

shown in Figure 5a.