CL4490 Hardware Integration Guide
Version 1.0
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Can I implement a design using just Txd, Rxd and Gnd (Three-wire Interface)?
Yes. However, Laird strongly recommends that your hardware monitor the CTS pin of the
radio. CTS transitions logic High by the radio when its interface buffer is getting full. Your
hardware should stop sending data over the serial interface at this point to avoid a buffer
overrun (and subsequent loss of data).
You can perform a successful design without monitoring CTS. However, you need to take
into account the amount of latency the radio adds to the system, any additional latency
caused by Transmit Retries or Broadcast Attempts, how often you send data, non-delivery
network timeouts, and interface data rate. Polled type networks, where a centralized host
requests data from the surrounding hosts and the surrounding hosts respond, are good
candidates for avoiding the use of CTS. This is because no one transceiver can monopolize
the RF link. Asynchronous type networks, where any radio can send to another radio at any
point in time, are much more difficult to implement without the use of CTS.
