The main problem that I encountered with the development of the PCB was being able to allow for another board to slot on top, while retaining the current functionality and adding more with the extra board. My first design incorporated a set of headers for the transfer of signals and to stabilise the upper board and a single, two pin male header for power transfer. From my second design onwards I proposed to use a pair of 6 pin Arduino stackable headers, this meant that I could plug multiple boards directly on top of each other (e.g. Photovore, Edgebot, H-bridge) As only 4 pins are used for the Photovore-Edgebot signals (Excluding the two/three power pins) It leaves 5 pins for other signal transfers of future boards.
Another dilemma I faced was how to keep the feature of modularity when it came to inputs/outputs, the first through to fourth designs used screw terminals to connect the external switch input pins and the motor outputs. However, this meant that you could have to use a screwdriver every time you added or took off a board, which would both time consuming and tiresome, especially if you do not have a fine screwdriver to hand. Screw terminals are relatively large, therefore taking up unnecessary space on the PCB and thus increasing the cost. So I replaced them with right angle headers so that you can simply slot the sensors in and out, if you wanted a more permanent solution, you could also solder the sensor directly into the header PCB holes.
The latest version of the board also uses a trim-pot so that you can change the reverse time delay of one of the motors, the capacitor values were changed accordingly.
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| The schematic |
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| The PCB |
The latest Edgebot design files (v0.5) can be downloaded from Dropbox.
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