Arduino “Mega Shield”

The main purpose of this shield is the ability to test various circuits and sketches. On the back it carries an Arduino Mega or Due, and on the front my Monitor/Tester. On the board, all 16 analog pins and 35 digital/PWM pins are connected to the 64 pin male DIN-connector. The board is then inserted into Phönix carrier with screw-terminals for every 64 pins. The Phönix carrier came with a DIN-rail mounting flange, but I took it off and mounted it on a thick fluorescent acrylic plate, with some LED’s inside to make it glow in the dark.

On the board I have a couple of test circuits:

  • 16 channel multiplexer for 16 NTC temperature sensors, to test cheap temperature measuring techniques with software linearization.
  • One analog input op-amp with a simple R/C-filter for various feedback tests with servo motors.
  • Two analog output op-amps with R/C-filter to convert PWM to DC-level, primarily for testing envelope waveforms for analog synth.
  • Two RS485 circuits with termination resistors, for testing my new small-BMS project.
  • One pressure transmitter for HVAC test purposes.
  • A small Real-Time-Clock module communicating via SDA/SCL
  • 4-pin SDA/SCL connector with separate 3V regulator for testing remote sensors
  • A small ESP8266 WiFi module communicating via Rx1/Tx1
  • 6 dipswitches on digital inputs
  • Two PWM outputs via power MOSFET with 100 ohm resistors in series with the drain. The resistors are mounted so that they can heat up the two temperature sensors on my Monitor/Tester, to form a feedback loop for testing PID regulators.

This is how it looks without the Monitor/Tester:

And here on the back is an Arduino Due. I always buy these type boards without headers, and then I solder in the headers with the long pins. In this way I can put even more shields also on the backside:

I needed even more test facilities, so I made a “backside shield” to carry a TFT display and a LAN module. These are both controlled via MISO/MOSI port. The board also carries a voltage and current monitor (form Adafruit, on SDA/SCL) that can be coupled into the power supply for the Arduino.

Finally the board has a place for testing the little ProMini form RobotDyn, that I use a lot for simple tasks. Of cause I first have to take out the big Arduino and couple the whole ting together again. The ProMini then hooks up to the right pins for monitoring and testing. Here is the “TFT-LAN-ProMini-Power-Shield” shown without the TFT and ProMini:

I also mounted a little test stepper-motor with a connector, acrylic face-plate and a circular pointer. It sits on top of the Monitor/Tester. Here is everything put together in a maximum configuration, including the TFT and some cables to RS485 and I2C. It is almost like a heavily decorated Christmas Tree 🙂 :

PS. One smart feature of the shield is the ability to connect the 64-pin connector directly to a set of terminals on a breadboard (socket board). When the board is taken out of the Phönix carrier, I have a 64-lead ribbon cable with 64 pin female DIN-connectors in both ends. One end goes to the connector on my board, and the other end is placed alongside the breadboard.

You can see the schematics here:

Arduino Shield

Mega Shield Aux