User manual

WiFly GSX
www.rovingnetworks.com WiFlyGSX-um 7/16/2010
809 University Avenue • Los Gatos, CA 95032 • Tel [phone] • [e-mail]
~ 27 ~
the sensor header. To wake on UART CTS place a jumper from pin 10 on the Evaluation board header to
pin 3 on the sensor header.
To enable wake on RXD, use set sys trig 1.
It should be noted that the first (or possibly multiple) byte sent into the module will likely be lost, so the
designer should take care to send a preamble byte to wake up the module before sending valid data bytes. A
better way to do this is to use the CTS input to wake the module, and wait until it is ready to accept data.
To enable this, use set sys trig 2.
10.4. UART Receiver, RTS/CTS Hardware Flow Control
The UART receive buffer is approx. 1500 bytes, and at lower baudrates (less than 115K) the system can p
send data over TCP/IP without the need for flow control.
Depending on the frequency and quantity of data begin sent comm parameters will optimize Wi-Fi
performance by specifying when the system sends IP packets. To minimize latency and TCP/IP overhead
use the flush size or match character to send data in a single IP packet. In most cases you will want to set
the flush timer to a large number to avoid fragmentation. For high throughput cases increase the UART
baudrate, set the flush size to 1460 and flush timer to a large value so full IP packets are sent.
You can control the packet forwarding 3 ways:
set comm match <value> sets the value of the packet terminator. Each time the match character is seen
an IP packet will be sent. "set comm match 0xd" for example forwards once a 0xd hex character is seen..
set comm size <value> sets the flush size, the size is the number of bytes received before forwarding.
maximum value = 1460 bytes which is the size of a single Ethernet frame.
comm time <value> sets the flush timer, this is used to make sure that any partial data sitting the RX buffer
if no additional data is seen for “value” milliseconds. For example "set comm time 1000" would wait for 1
second after no data was sent.
When sending more than a few hundred thousand bytes in a single transaction you should enable hardware
flow control. Your hardware will need to actively monitor CTS.
Flow control is not enabled by default. Flow control is set using with the following command.
set uart flow 1
It is possible to operate higher baudrates (greater than 115K) without flow control if packets are uniform
and an application protocol is used to ensure that each packet data is delivered on the remote side before the
next packet is sent.