Putting SportVFR all together

I found a renewed interest in this SportVFR in the purchase of a Pietenpol AirCamper.

Yup... that's me the Yeller-Barron 

The plane came with a full set of your traditional steam gauges they work well enough and I see no reason to replace them (yet).  But, I want to instruct some in the plane.  The front seat has a full set of controls except brakes and any instrumentation.

Period appropriate gauges in the back... Airworthiness/Registration in the front.  No instruments, front seat flying is tricky

 Yup... you get where this is going.  I need a cheap non-certified yet perfectly functional front seat instrument set.  Enter SportVFR.

I spent this weekend wrapping up the project and I think I'm getting very close.  First, I swapped out the MCU.  The prior post suggested a Spark Electron.  I have plans to try that later, but I didn't want my v1.0 to have issues with the EMF the cell transmitter would produce.  I'll have enough problems getting working what I have.

I chose the SparkFun Pro Micro, which is probably the best micro-sized Arduino compatible proto board out there.  It has built in USB Support via the ATMEGA32U4 programming is plug and pray easy.  To be compact, it purposely doesn't pin-out all the GPIO; the 17 provided are more than enough for this modest project. Best of all, they can be had for $5 in small quantity.

So I'm pulling the project together around the Pro-Micro.  Here's the final BOM (drop the test into ebay to find any parts, they all come cheapest or at all from China)

Pro Micr ATMega32U4 5V 16mhz	$4.99
HMC5983 BMP180 Magnetometer / Pressure Module	$3.50
MPXV7008DP Airspeed sensor	$14.98
1602 16x2 Character Display LCD I2C	$3.22
12mm Shaft Rotary Encoder with knob	$3.51
Oil Pressure Sensor 80PSI	$13.98
Oil Temperature Sensor 1/8 NPT	$9.79
HAL Effect sensor NPN	$3.49
Project enclosure with proto board	$5.23
Total	$62.69

At just over $60 with all sensors, this is perhaps an order of magnitude less than anything else out there.

So I assembled it all. I will make a post soon with the full schematic including all the voltage divider resistance values and layout. There was a trick on the Oil Pressure as it has a very low resistance at static pressure. 

Ok, so what does it look like?  It's in an enclosure, it has screw terminals for power and external sensors. I haven't drilled any wholes in the enclosure yet, but I'm just about ready to do that.








Pinout:

I2C - HMC5983, BMP180, 1602 Display (SDA /SCL / VCC / GND

Oil Pressure - Uses multiple resistors to A0
MPXV7002DP Airspeed - A1 direct
Oil Temperature - Uses a Voltage Divider to A2
System Voltage - Voltage divider to A3
Encoder - TBD, I haven't installed it just yet

That's really it! Hard to believe.  The rest is just programming... see the git repository.  The version posted is still in draft form, I will finalize all this soon and post the corrected updates.