Surveyor Robotics Journal
Surveyor Corporation home page
Subscribe to a syndicated RSS feed.
Archives
November 2008
October 2008
September 2008
August 2008
September 2008
August 2008
July 2008
June 2008
May 2008
April 2008
March 2008
February 2008
January 2008
December 2007
November 2007
October 2007
September 2007
August 2007
July 2007
June 2007
May 2007
April 2007
March 2007
February 2007
January 2007
December 2006
November 2006
October 2006
September 2006
August 2006
July 2006
June 2006
May 2006
April 2006
March 2006
Februray 2006
January 2006
Sat, 02 Sep 2006
update on SRV-1 + WiFi ...
An SRV-1 is now running with an on-board WiFi module (the Lantronix WiPort). It's not pretty, but it actually works quite well.
It was actually a simple installation. After removing the Zigbee radio, 2 hex spacers (3/4") were added in place of the SRV-1 controller mounting screws on the left side of the circuit board. (3/4"). After acquiring a small circuit board (1.8" x 2.8" or 47mm x 72mm) from Radio Shack, the WiPort module and antenna were removed from the WiPort evaluation kit, added a 3.3V regulator (LD1117) to the circuit board, some holes were drilled, and the WiPort was mounted on the new circuit board.
Because the spacers are grounded, it was only necessary to attach the WiPort ground to the rear spacer through the screw. A WiPort PCB connector was available from www.gridconnect.com for $10, though it's likely possible run wires directly into the WiPort connector. In any case, only 3 wires had to be attached from the WiPort - the 3.3V supply (WiPort pin 1), which came from the center pin of the voltage regulator, the RXD0 receive data signal (WiPort pin 5), which went to Pin 3 of the XBee radio connector, and the TXD0 send data signal (WiPort pin 4) which went to Pin 2 of the Zigbee radio connector. Finally, a wire was run from the battery input connector on the edge of the SRV-1 controller to the rightmost pin on the voltage regulator.
The WiPort module was first fired up with just the 3.3V and ground lines connected first just to make certain it was happy with the voltage regulator, testing that it was accessible via the WLAN, and then we connected the serial lines. Once the serial lines were connected to the Zigbee radio socket, the robot fired up and ran without problem.
A few notes about operation - it was possible to run SRV1Console and LPC21ISP without modification on Windows, using a "com port redirector" that maps a virtual com port to a telnet connection, and data flowed transparently. It is even possible to run LPC21ISP this way to program new versions of firmware to the ARM7. However, there were limitations in the WiPort such that LPC21ISP couldn't run at data rates higher than 230kbps, and SRV1Console couldn't run faster than 460kbps (the data is pretty badly scrambled at 921kbps). This has been reported to Lantronix tech support, as the module is spec'd to handle 921k, but in any case, the robot runs well at the lower data rates.
The WiFi connectivity is good with a couple of Belkin54g 802.11b/g router/access points, and handoff seems to be seamless as the robot drives around. We haven't tried to measure power consumption, but it's clearly higher than the XBee radios. Also, while the frame rate was probably 4x faster with the 460kbps connection that connections via Zigbee, it seems that the frame rate could be higher, so another look at timing in the camera interface code will be on the to-do list.
We're waiting on another WiFi module to integrate in approx 2 weeks, though it won't be in production for a few months. The Lantronix WiPort is certainly promising, and we'll be happy to share our results with others who wish to experiment with adding WiFi to the SRV-1.
Posted Sat, 02 Sep 2006 23:00 | HTML Link | see additional stories ...
Surveyor Robotics Forum now exists ...
Please visit http://www.surveyor.com/robot_forum.html, and let us know if there are any issues in setting up accounts or generating posts.
Posted Sat, 02 Sep 2006 23:00 | HTML Link | see additional stories ...