Connecting the GPS (#28146) to the BS2 HW board.

Vinator

Let me apologize in advance if this is somehow common knowledge or a commonly asked question that I missed the answer too.
I'm a newcomer to the world of the stamp, and a very amateur electrical hobbyist so bear with me please.

After having read the FAQ for the BS2 (http://www.parallax.com/Portals/0/Downloads/docs/prod/stamps/basicstampfaq.pdf) it appears as if it's on-board regulator is only meant to supply about 50ma across the vss/vdd pins.
According to the GPS doc it's (the gps's) typical load @ 5v is 115ma. This would seem to be drawing far more current than the BS2 was designed to handle.

I'm genuinely surprised that I haven't run across any tutorials with recommended wiring guides.
So either I'm missing something glaringly obvious to almost everyone but myself, or a lot of people are pulling more current from their chip than is recommended.

So am I missing something regarding the stamps regulator and ability to supply current?
Should I be using the vin pin with some inline resistors?

Thanks in advance for any helpful replies!

Post Edited (Vinator) : 10/15/2009 9:22:37 PM GMT

Chris Savage

Hello,

You are referring to the ratings for the on-board regulator on a BASIC Stamp Module. This is not typically how accessories are powered though. Most often the configuration is that the BASIC Stamp Module is on a Board of Education, Super Carrier Board or some other development board that is supplying power. The GPS then uses the 5V from that source. The only way you’d be required to use the BASIC Stamp modules on-board regulator is if you had the BASIC Stamp Module installed on a breadboard or using the original carrier board and your power supply was not 5V. Is your BASIC Stamp module installed on a development board? If so, which one?

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Chris Savage

Parallax Engineering
50 72 6F 6A 65 63 74 20 53 69 74 65
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Vinator

I have a Board of Education, and the chip is seated in the socket.
I was under the impression, and seemingly wrongly so, that vin ran to the BS2, and the vss/vdd sockets running along the top of the breadboard were connected to the vss/vdd pins of the stamp to provide regulated +5 voltage.

It seems you're saying that the vss/vdd sockets are hooked up to a separate regulator as part of the BoE's power circuitry.
This makes a lot of sense, it just didn't occur to me to check that before posting.

And now that it occurs to me to look... the BoE seems to provide 1amp of current.
Thanks Chris!

Chris Savage

Correct...the large 3-legged device with the heatsink on-board is the BOE regulator and can supply up to 1A (although practically it would be more like 500 mA in this configuration). So you should be all set using the V_DD pins on the board since they come from the BOE. Take care.

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Chris Savage

Parallax Engineering
50 72 6F 6A 65 63 74 20 53 69 74 65
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