Adruino updates: APC w/ESP8266 and OLED LCD


So my little aeroponics project is growing beyond its real needs, but once you start assembling legos it's hard to stop.  I've added an ESP8266 for wireless connectivity and a really small OLED LCD display.  The latter will let me monitor the system without either serial (ftdi Basic) or wireless connected.

breadboard

The breadboard really isn't necessary at this point. The only thing it holds are the LED and its resistor plus Vcc and GND busses.

Fritzing made it easy to layout the prototype on a breadboard, though after working through cleanup of the schematic and the pcb I found some problems.  First, I intended to use a USB breakout board from SparkFun connected to some headers on the PCB.  But if you try to wire this in Fritzing the circuits are not closed at the headers and Fritzing gets confused.  Instead, I found a USB part (from SparkFun) in the Fritzing parts libraries that had through holes.   Through holes are important because I need to place some traces on the PCB on the bottom side of the board.  The USB  part had connectors that were labeled Vcc and Ground which allowed Fritzing to close circuits and allowed me to create traces the way I needed them.

pcb

The layout is about 8″ x 5″ which could be a bit pricey, not to mention difficult to fit in a decent sized enclosure. It will have to be scaled down.

The next problem came after the PCB was fully routed.  The size of the PCB makes it prohibitive to get made.  OSH Park charges about $5 per square inch.  With my PCB at 8.8 x 5.3 inches that cost for a small production run (3 boards) would have been around $200.  Not horrible but really, this is such a simple project why waste the money?

So now the plan is this:

  1. Remove the ftdi basic. The Pro Mini just needs headers to connect the FTDI Basic.
  2. The OLED LCD doesn't need to be on the PCB. It can be connected with wires. This will allow the display to be freely placed in the most appropriate location without respect to the positioning of the PCB.
  3. With these changes I should be able to mount the ESP8266 on the back of the PCB and
  4. move the TinyRTC and USB power to a second PCB, mounted vertically with spacers. That will reduce the costs of the PCBs significantly. In fact, I should be able to do the whole thing with perfboard.

So my cost goes next to nothing.  In the end I should have two perfboards mounted together with spacers with the LCD mounted on a third perfboard (or without possibly) on some user-facing wall of the enclosure.

I still haven't gotten to the enclosure but that will come after I find out how big this thing will be.  I still have to add in the 4 channel relay board too, plus the wires connecting all the boards and the power outlets together.

Duh

Just posted this, then went back to review the layout in Fritzing.  I realized that the ruler part I used to measure the PCB had two sides: inches and cm.  Guess what idiot was reading the cm side?  Yeah.  That's the guy.  So it looks like the whole design may fit completely on the perfboards.  The PCB would only be 3.3″ x 2″.  Much more affordable.

Just goes to show:  there is always one more thing to review….

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