Digital Soldering Station Hardware Using Arduino Nano

Arduino Nano Digital Soldering Station Circuit Schematic Diagram

Arduino Nano Digital Soldering Station Circuit Schematic Diagram

Arduino Nano [reference 1] is chosen for the digital soldering station project since it has complete features to implements all functions. Other microcontroller can be used as long as it has the following features:

  • Eleven  digital outputs to drive three units of seven segment displays, 3 outputs for activating the common pins (the employed seven segment displays can be common cathodes or common anodes), 7 output to drive the segments, and 1 output to drive the opto-isolated powerline driver.
  • The digital outputs are able to drive at least 20 mA current both in sink and source modes, since the 7 segment display is driven directly (through a resistor) by microcontroller’s port.
  • Two digital inputs to read the up-down buttons/key-switches.
  • Two analog inputs to read the thermocouple sensor and the ambient temperature compensation sensor with at least 10 bit resolution.
  • Internal counter for timing, and this timer or counter should run independently without cpu control. An interrupt handler that process the timer/counter’s interrupt (for example to produce longer bit counting/timing) is acceptable.
  • Internal EEPROM or non-volatile memory for storing temperature setting.

The circuit schematic diagram shows no power supply circuitry, which should consist of a small adapter from 220V AC to 5V DC required by the Arduino microcontroller. We can easily built this small power supply using 100-350 mA 220VAC to 9-15VAC transformer, bridge diodes, capacitor, and 7805 linear voltage regulator.

The 7-segment displays are actually 3 independent units, which are connected in parallel except the common pins. The dot pins are not used, so only the 7 segments pins are paralleled. The digital inputs for the up-down button (S1 and S2) are A0 and A1, which are analog inputs by default of Arduino initialization, but here must be set to digital inputs by custom initialization.

Reference

  1. Arduino Nano Board, https://www.arduino.cc/en/Main/ArduinoBoardNano

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Digital Soldering Station: An Integrated Hardware and Software Designing Case Study

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