DS601-4

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©2004 Reg. No. 227 4001, ENGLAND

Page 3

Smart Com Radio Transceiver IC

RF600T

(Confirmed). Note that confirmation is given when the data block is stored in the buffer of node ‘B’ and not when it

has been delivered to the host at node ‘B’.

All message transfers are tagged with the addresses of both the origin and destination, thus ensuring secure data

transfer at all times. Either node ‘A’ or node ‘B’ can initiate a transfer but only one direction of transfer can be

active at a given time. In the event that the originating node does not get confirmation of receipt of the data packet,

the software re-tries the transfer five times after which node ‘A’ will output an error message to the host in the form

of the ASCII character ‘F’ (Failed).

Correct reception (or otherwise) of a data packet is thus acknowledged and the host devices are relieved of most of

the workload of ensuring that data transfers occur as required.

System Operation – Broadcast Mode

If operation in the broadcast mode is required then on power up the MODE pin should be pulled low. If however a

device has been used in the point to point addressed mode or if its status is unknown then status erase must be

carried out using the following procedure. With the unit in addressed mode (power up with MODE low) the LEARN

pin is grounded for a period of 5 seconds and is then allowed to float. The status LED then flashes slowly for 3

seconds to indicate that the device is erased.

System Operation – Addressed Mode

Each RF600T is programmed at manufacture with a 24 bit serial number which uniquely identifies the device. In an

addressed point to point system, these serial numbers are used as the device address for the nodes in the system

and non-volatile eeprom memory in the device stores the address of the ‘other’ node in the system.

If operation in the addressed mode is required then the following procedure has to be followed to allow the two

nodes in the system to operate together.

The two nodes, ‘A’ and ‘B’ are placed within radio range of one another are powered up with the MODE

pin held high.

The LEARN pin on one device – say ‘B’ is briefly taken low, placing the node into learn mode. The

LEARN/ERASE status LED on ‘B’ comes on and remains on for 20 seconds. If within this period, no

‘learn’ data packet is received (see below) then the LED will be extinguished and the device will operate

normally.

At node ‘A’, the LEARN pin is briefly taken low. The LEARN/ERASE status LED will then come on and

node ‘A’ will transmit its address.

Node ‘B’ will receive and store the address of ’A’.

Node ‘B’ sends back to node ‘A’ both its address and that of node ‘A’.

Node ‘A’ receives and stores the address of ’B’ and confirms to ‘B’ that it has received the information.

Both node ‘A’ and ‘B’ LED's flash their status LED’s rapidly for 3 seconds to show that they have

learned each others addresses.

Note: Other nodes which may be active will ignore this transfer since they have not been placed into

learn mode.

If notification of correct reception (or otherwise) of data packets is required but it is not possible or desirable to

carry out the learn process then a modified addressed mode of operation may be implemented. In this mode, both

nodes have their eeprom memory erased using the erase process, thus placing null serial numbers ($000000) for

the ‘other’ node into both device eeproms. If the devices are now employed in addressed mode (power up with

MODE pin high) they will operate as if they had learned one another’s identity using the normal learn process. Note

that in this mode, only two device may be employed within range of one another since data transfer is effectively

carried out as a broadcast to all nodes with a null address.