I swapped this custom connector in place of the DB9.
The product is really quite good, so I'll be sending a check soon.
I ordered a pair and got them within a week or two. Incidentally, I discovered that the odd-ball Garmin GPS connector is available as a standalone part from this site. I soldered everything together on a Radio Shack copper-clad perfboard and added LEDs for power (green) and RX (red), then soldered the wires to a DB9 female connector so I could use the original Garmin cable. Leaving Q2, R3, R4, and R5.ĭitch the diode (D1) and capacitor (C1) and TX circuits The RX half of the circuit eliminates the D1 diode and C1 capacitor, and the TX circuit: Q1 transistor and R1, R2 resistors. Since the GPS only spits out data and doesn't take commands from the MCU, the receive (RX) side of the level shifter circuit is all that's required to interface the Legend GPS. Some time ago I made a level shifter device to interface various microcontrollers with my PC. One can use a MAX232 to shift levels to MCU-friendly 0-5V or 0-3.3V but why dink around with that when a transistor, a few resistors, a prototype perfboard, and a few minutes with a soldering iron will do the job. RS-232 uses +/-12V signals that will burn your average microcontroller's input pins to a crisp. Like most GPS units, the Legend outputs NMEA 0183 serial data using RS-232 protocol.
It so happens I have a Garmin eTrex Legend that I can use for prototyping until I buy a much better GPS module for the robot. If you missed prior posts, I have entered the 2011 Sparkfun Autonomous Vehicle Competition (AVC).įor reliable navigation around the Sparkfun building in Boulder, CO, I plan to equip the RC truck I purchased with a GPS, interfacing it to a microcontroller.
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