New SX Controller Board and SX-Key (USB) User needs power help

Bill Chennault

All--

I downloaded the latest SX-Key (USB) software (version 3.2.92h BETA), plugged in a center positive, 9vdc, 1000ma wall-wart and powered the SX Controller Board up, placing the power switch in position 1. The red LED nearest the power switch came on, as the documentation indicated. (Red kinda surprised me.)

Since I know nothing about SX/B, I copied the "High-Low.SXB" program into the IDE. I saved the program via the "Compile" function and moved the power switch to position 2 . . . the second LED, indicating that power had been routed to·the V+ terminal and hence to any external devices I may have connected (there were none) did not light.

Is the 9v wall-wart too small? Without a load, it supplies 13.38vdc. The SX Controller Board documentation states that anything between 9vdc and 24vdc is fine.

Will you please help?

Thanks!

--Bill

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You are what you write.

Bean

Bill,
I'm sure the supply is not at fault.

The outputs on the Prop-SX Controller are open-collector. They can only connect to ground or be open.

So you must connect the + side LED (or whatever you are controlling) to the V+, and the minus side to the screw terminal (don't forget a resistor too).

Bean.

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JonnyMac

If the V+ LED does not light when the power switch is in position 2 then the board may have a problem. As Terry points out, the ULNs used on the board for the terminal outputs are open-collector and can only switch ground, so V+ provides the positive side of the circuit for relays, etc. With the power switch in position 2 you should be able to read your power supply voltage between the V+ and GND terminals.

Bill Chennault

Bean and JohnnyMac--

You must have read my mind . . . er, BS2 experience! BOTH of you are correct.

I WOULD have hooked it up backwards, but I carefully examined the board first. I believe the problem is a slight manufacturing defect . . . the resistor on the second LED, the one that indicates the power switch is in position 2, appears to be unconnected . . .



What do you think?

When I IGNORED the lack of a second power·LED and hooked the test LED up to V+ and OUT0 the test LED blinked just as it should.

I MIGHT be able to "skootch" the resistor over its pad and it MIGHT connect. However, if it broke off then I would doubtless void the warranty.

Will you tell me what speed the SX Controller Board runs at when the SX-Key (USB) is attached and what speed it runs at when the SX-Key (USB) is not attached? (400KHz and 4MHz, respectively?)

If I want to speed the SX Controller Board up to 20MHz or 50MHz, do I simply buy the part from Parallax and plug it in the three pin female header between the SX Key connector and the DB9?

Thank you very much!

--Bill

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You are what you write.

Post Edited (Bill Chennault) : 5/14/2008 6:42:52 PM GMT