Sherline 2000 CNC - Part 3
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2-21-2002
Another day, yet another breakout board! This is a "smart" board with an onboard CPU (PIC 16F628). that disables current to axii that aren't moving. It keeps watch on the 'step' signal--no change for 1/4 second, and the current to that motor is cut off. When a step is received, it immediately re-enable the axis.
I designed it to use the 'standard' EMC pinout:
|
DB25 Pin
|
Signal Name
|
Function
|
|
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2
|
D0
|
X Direction
|
|
|
3
|
D1
|
X Step
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|
|
4
|
D2
|
Y Direction
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|
|
5
|
D3
|
Y Step
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|
|
6
|
D4
|
Z Direction
|
|
|
7
|
D5
|
Z Step
|
Here is the source code for the Microchip 16f628.
I made another pair of driver boards, for the z-axis and x-axis.
These have two power supply connectors, for more voltage. The z-axis is now driven by a 17V supply and a 24V supply, the x-axis has two 12V supplies. But why not just have one power input and use one power supply, you ask?
Two reasons. First, the 5V regulator is supplied by just one power input, so it doesn't overheat. Also, 12V power supplies are very cheap, 24V power supplies are available, but voltages above that are not so readily available surplus.
The increased voltage now allows the Z-axis to zip up and down at almost 20ipm -- twice the speed as before.
I've started using a g-code interpreter called TurboCNC. It has just about every feature I would consider adding to Stepster! It's only $20, and you get to see the source code!
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