Sunday, February 04, 2007

Building the new Tommelise controller board

I'm having to stay up fitting neural nets this evening. That leaves me a bit of free time while these things grind on my dual Xeon workstation. I've been slowly building up the new microcontroller board for Tommelise. I've taken a lot of pics for documentation but I've not the time to write that up this evening, so I'll just show you where I am at the moment.

You can see the PIC 18F4610 in the middle of the board and sockets for two 754410 dual Darlington motor controllers at the bottom. The power conditioning voltage regulators and capacitors are at the upper right of the board with a two pole connector for 12v power.

To the left of the PIC chip is a 20 MHz timing crystal that sets its speed.

The little 1K Ohms resistor connects 5v power to pin 1 of the PIC chip and the black and orange lines just to the right of the PIC chip supply grounding and 5v power respectively.

The other two, longer black and orange lines carry serial comms to the two, two pole connectors at the top of the board that are connected to that multicoloured flat cable at. That cable is connected to a comms card that turns PIC serial comms into something my workstation's serial port can understand.

This PIC chip allows for direct USB communications with a PC. I haven't got around to getting that working just yet. Right now I'm more interested in getting Tommelise to actually make something useful than I am on guilding lillies, so to speak, so USB is not near the top of my priorities just now.

Add one power transistor and five more of those blue two pole connectors to attach all the sensor input lines and carry power to the Mk 2.1 extruder and the board will be complete. It's not too complicated a line, even for newbies. It does take a bit of patience and care in order to get it going properly, though. I'll be taking you through all that step by step in the documentation in a few months.

BTW, I've tested the board and it responds to serial comms properly. Now to get the dual Darlington chips hooked up and running the gearmotors. I got tired of wasting dual Darlington chips so I bought some cheap sockets for this board. Tommelise doesn't draw a lot of amperage to run its motors, so I can get away with this, I think. Ordinarily, putting dual Darlington chips in sockets is not a very bright thing to do.

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