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RANSCEIVER
2
Operation
RF650
The Host Data Rate pins are read when the PD pin goes high. The RF650 must be put into standby mode by
taking the PD pin low in order to change the selection.
The size of RF data packets are set during configuration. If fewer bytes are received by the RF650 than the
preset size, then after 10ms from the last byte received from the host, the RF packet will be processed
(expanded to meet the preset packet size) and transmitted. The RF data packet size must be set the same for
transmitter and receiver, otherwise the received packets will be discarded.
In order to optimise data rate , in a point-to-point configuration where data is mostly being sent in one
direction, the packet size for one data direction can be set to the maximum size, however the reverse direction
may be set to a smaller packet size, to implement an acknowledge reply for example.
The RTS pin overrides the timeout value. If a short data packet is sent, RF transmission will start as soon as
the RTS pin is taken ‘high’ after the last byte is sent to the module.
The RF650 contains an on-board data buffer equal to two data packets. Therefore if RTS is asserted (then the
host is unable to receive data) the RF650 will store a max of two data packets, all further data packets
received will be discarded.
No RF packets will be received by the module when it is in power down standby mode.
Each RF650 has its own preset address. This is set during configuration. Any data received is examined and
the address header embedded within the data packet is compared with the RF60 address. Only data received
with matching address will be processed and output to the host, all other data will be discarded.
All RF650 modules are shipped with a default address of 7E7E7E7E.
2.1 Operation Modes
The addressing protocol employed enables many different configurations such including:
one-to-one operation;
for point to point data communication
broadcast operation;
where a single master address many RF650 modules concurrently. (using many
RF650 modules set to the same address),
one-to-many;
A network consisting a master and many slaves (the receivers all have the same address)
many-to-one;
where the transmitters all send to a single receiver address.
Because each RF650 can contain a unique address, multiple RF650 networks can co-exist in the same area.
2.2 Serial Data Format
The RF650 serial format settings are:
Baud Rate: Defined by DR1 and DR2 Pins
Data Bits:
8
Parity:
None
Stop Bits:
1
Flow Control: Hardware
2.3 CTS timing
With a standard buffer size of 30 bytes, CTS is asserted 41uS after the buffer is full. In cases where less
than 20 bytes are sent CTS is asserted after a timeout of 10mS.
DS650-6 June ‘06
©2006 RF Solutions Ltd, www.rfsolutions.co.uk
Tel 01273 898000 Fax 01273 480661
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