Navibee GM720 connected to Arduino
Here is another quick demonstration of USB Host Shield 2.0 Library. This article describes how to communicate to Navibee GM720 GPS receiver based on SiRF Star III chipset and PL2303 USB to serial converter. This GPS device is available on eBay for around $25 new, used units can sometimes be found for $10 or even less. The receiver has waterproof case, magnet mount and comes with 6 foot cable. Another nice feature of this device is its 40mA current consumption. Here are some pictures of the unit – PCB, internal antenna, as well as front and back of the original packaging.
“Classic” GPS receiver sends and receives NMEA 0183 messages via serial port at 4800 bps. Modern GPS units often support faster speeds and vendor-specific messages. However, they mimic classic GPS unit behavior – at power-on they start sending basic navigation messages at 4800 bps. The following sketch outputs messages, received from Navibee GM720 GPS unit via its built-in PL2303 USB to serial converter connected to USB Host Shield. Full text of the sketch is available on gitHub, below is just a fragment where speed is set to 4800.
The OnInit() member function is called to change serial parameters after initialization. A lc structure of type LINE_CODING is declared on line 14. It is filled with baud rate (line 15) and number of data bits per byte (line 18) and then sent to Pl instance in line 20.
Compile the sketch, load and run. The output is depicted on a screenshot after the code fragment.
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