Parallax GPS

MegaSpin

does the Parallax GPS work with the Propeller Proto board? Also, how does it compute the heading? Does it actually have to be movig?

I'm new to this stuff! Help is much appreciated.

Chris Savage

Hello,

Yes, the GPS Module is compatible with the Propeller Proto Board. It calculates heading based on the current coordinates in relation to the previous reading. Because of this it needs to be moving to calculate the heading accurately. More expensive GPS units use a separate compass for this purpose.

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Chris Savage
Parallax Engineering

Timothy D. Swieter

MegaSpin -

I think the Parallax GPS module is 5V compatiable. So, you need to be sure to supply it with the 5V DC power supply. Also on the serial output you may want to put a 1K resistor to limit the current into the Propeller pin. I haven't set this up myself with the GPS module, but I know in general this should be done on 5V devices.

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Timothy D. Swieter, E.I.

www.brilldea.com·- Prop Blade, LED Painter, RGB LEDs, uOLED-IOC, eProto fo SunSPOT, BitScope
www.sxmicro.com - a blog·exploring the SX micro
www.tdswieter.com

sylvie369

I did have a setup with the Parallax GPS going into the Propeller, and yes, I did use a 1K resistor going into the Propeller pin.

MegaSpin

Thanks for that info, it really helps for a noob like me

In general, should a resistor be used for serial outs to the propeller?

Timothy D. Swieter

Well....not exactly. The reason we are using it here because a 5V system is talking to a 3.3V system and we want to drop the voltage (or limit the current) from the 5V system to the 3.3V system. A 3.3V serout out on a device is OK to connect directly to a Prop.

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Timothy D. Swieter, E.I.

www.brilldea.com·- Prop Blade, LED Painter, RGB LEDs, uOLED-IOC, eProto fo SunSPOT, BitScope
www.sxmicro.com - a blog·exploring the SX micro
www.tdswieter.com

Paul Baker

Generally anything that uses the _exact_ same source doesn't need a resistor, but if the sources are different use a resistor when going from Higher source to lower source. This can is true even if the voltages are the same (but gotten from different sources). Say your operating the Propeller off a 3.3V regulator and you plug a sensor board that operates at 3.3V but you feed 5V to the board (IOW it has it's own regulator on it's board), then resistors should be placed on all signal lines between the Propeller and the sensor. This is because the two 3.3V sources may not actually be the same, one might be at 3.2V while the other is 3.4V, so the resistors are needed to limit any current flowing due to supply mismatch.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.