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be full, resulting in loss of data. (The EZL-80c serial port has a 1-kbytes reception buffer
and 512 bytes transmission buffer.)
The serial port hardware flow control of EZL-80c is implemented RTR(ready to
receive)/CTS (clear to send) protocol. The RTS port (RTR is called RTS in EZL-80c for
convenience) is an output port that becomes „active low‟ if storage space is available in
the reception buffer of EZL-80c. Meanwhile, the CTS port is an input port, which takes
the active or inactive state of the RTS pin on the communication counterpart to which
the CTS pin is connected.
The interconnection between the user‟s processor and EZL-80c should be done as
follows.
3.3.2.
Flow Control Scenario
The following is a flow control scenario.
(It is assumed to be measured at the pins of EZL-80c.)
Initially, EZL-80c is ready to receive and transmit data, since RTS and CTS are both
low.
At position „A‟ the counterpart processor sends a signal that it is not ready to receive
data. Then, EZL-80c stops sending data.
At position „B‟ EZL-80c sends a signal that it is not ready to receive data. Then,
