Archive for November, 2006

Modular Layout and Wiring

November 1, 2006

Over the last weekend, I received a few mailorder parts for PCB assembly for ALIBE.  For ALIBE, having the layout be modular will help for a few reasons. 1) For extensibility, 2) to be able to isolate a part, replace or fix, 3) easily debug a part in isolation, 4) for “readability” purposes – that is understanding how the parts and circuits are laid out, wired, etc., and 5) for me personally, it helps me think clearly as I build ALIBE.




dsc03759.JPGThe approach I took was to build things into modules A) Brain Module (made of Propeller and PropStick), 5V regulator, Main Power Switch, LED indicators, and various PCB connectors for signals and incoming and outgoing powers.



dsc03760.JPGdsc03761.JPGHere’s the picture of the right side up. I am happy with the way it turned out.



dsc03765.JPGHowever, I am not happy at all how I ended up soldering the underside. I should really be doing this via a well designed and frabricated PCB. (On a side note, I should spend some time next weekend learning some of that stuff).



dsc03766.JPGNow, assembled on ALIBE’s Platform.



dsc03770.JPGThe next step was to build a 5v and 3.3v power “outlet” – sort of an onboard “extension chord”. What I did was took a standard RadioShack 1.5″x1.5″ general purpose PCBs and laid out the connectors. One Half of the board supplies 5v and the other half supports 3.3V (Half = the black line marker).



dsc03773.JPGI then basically connected the power supply from the “Brain Module” to the “Extension chord”. Made sure I measure the Voltage. I then took the Parallax LCD 2 line display and hooked it up as in this picture. The power is drawn from the “Extension chord”‘s 5v half and the signal line is hooked up to the “Brain Module”. It is important to note that since this is a 5v device, the signal is treated with a 220R Resistor. Shown in this picture with a heatshrink.



dsc03774.JPGNext in line is hooking up my custom made “Communcation Module” (based on AeroComm AC4790). Here’s the picture. Note that the CB is 3.3V device and connects to the 3.3V half of the “Extension Chord”. ALIBE also needs 3 signal wires from CB to the “Brain Module”. Here’s a picture.





I am planning on getting the other devices done by end of this weekend – I’ll blog more on this soon

ciao

Nagi