Stepper Control Question with DMX IO Board
I'm very new to this, so go easy on me! 
I've purchased the propeller board from gadget gangster and I've also purchased / built the DMX IO module here:
http://gadgetgangster.com/find-a-project/56?projectnum=201
I do Christmas and Halloween displays, and I'd like to start playing with props / movers for the show. I understand fundamentally how to control a stepper motor, and I've purchased a stepper motor as well as a stepper driver. The stepper driver requires 3 - 5v input on the direction and stepper pulse inputs. Here is my question / problem... In the documentation for the DMX IO board, I see where headers are available on the board for stepper motor control. It looks like a 3 pin header is provided - ground, 5v, and motor control. When I measure the voltage out on the stepper motor control, I'm only getting .7 volts - not enough to trigger a high pulse on the stepper motor. Ok, no problem I think to myself... Let me check the voltage on the "high power" terminals on the dmx io board... Nope. The output on those terminals is equal to Vin into the board. I can control that output by toggling the associated pin, however, it looks like the lowest input I can run the gadget gangster device with is 5.5 volts. The maximum input for the stepper driver is 5v.
I've setup a brief test with 4.5V input going into the gadget gangster board - it seems to run fine / without issue. When I do this, predictably, I seem to get usable voltages on the screw terminals. Do you see any issue running at 4.5 / 5 volts? I verified I can read the DMX values steaming in from my test computer, so it does seem fully functional. Is there a "better" solution for this? The transistors on the DMX IO board are TIP125s for the high voltage outputs and 2N3904 for the low voltage. I really expected the output from the 2N3904 (stepper motor header) to be 3.3 volts. I get 3.3 volts as expected at the output pin to the resistor just before the 2N3904...
The programming seems much easier than the electronics side! Thanks so much for any input you can provide. I must say, it's very fun creating code that directly interacts with a physical, tangible object. I've done some light computer programming in the past, but this is SO much more fun! I toggle a pin and a light comes on - read a photoresistor and trigger a totally different response from the gadget... Lots of fun!
I've purchased the propeller board from gadget gangster and I've also purchased / built the DMX IO module here:http://gadgetgangster.com/find-a-project/56?projectnum=201
I do Christmas and Halloween displays, and I'd like to start playing with props / movers for the show. I understand fundamentally how to control a stepper motor, and I've purchased a stepper motor as well as a stepper driver. The stepper driver requires 3 - 5v input on the direction and stepper pulse inputs. Here is my question / problem... In the documentation for the DMX IO board, I see where headers are available on the board for stepper motor control. It looks like a 3 pin header is provided - ground, 5v, and motor control. When I measure the voltage out on the stepper motor control, I'm only getting .7 volts - not enough to trigger a high pulse on the stepper motor. Ok, no problem I think to myself... Let me check the voltage on the "high power" terminals on the dmx io board... Nope. The output on those terminals is equal to Vin into the board. I can control that output by toggling the associated pin, however, it looks like the lowest input I can run the gadget gangster device with is 5.5 volts. The maximum input for the stepper driver is 5v.
I've setup a brief test with 4.5V input going into the gadget gangster board - it seems to run fine / without issue. When I do this, predictably, I seem to get usable voltages on the screw terminals. Do you see any issue running at 4.5 / 5 volts? I verified I can read the DMX values steaming in from my test computer, so it does seem fully functional. Is there a "better" solution for this? The transistors on the DMX IO board are TIP125s for the high voltage outputs and 2N3904 for the low voltage. I really expected the output from the 2N3904 (stepper motor header) to be 3.3 volts. I get 3.3 volts as expected at the output pin to the resistor just before the 2N3904...
The programming seems much easier than the electronics side! Thanks so much for any input you can provide. I must say, it's very fun creating code that directly interacts with a physical, tangible object. I've done some light computer programming in the past, but this is SO much more fun! I toggle a pin and a light comes on - read a photoresistor and trigger a totally different response from the gadget... Lots of fun!
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