Open-Source Microcontrollers for Science - Open-Source Lab: How to Build Your Own Hardware and Reduce Research Costs - page 67

4. R s → Digital Pin 43
5. E → Digital Pin 45
6. D 4 → Digital Pin 49
7. D 5 → Digital Pin 51
8. D 6 → Digital Pin 53
9. D 7 → Digital Pin 52.
It should be noted that Figure 4.5 shows the schematic for an Arduino Uno, and the code we
used to interface with the LCD was originally writen for it. This again shows the ease of port-
ing and adapting previous open-source hardware investment and code to your own projects.
The wiring diagram for the keypad is shown in Figure 4.6 . For this subassembly, only the
Arduino and keypad are needed. As can be seen in Figure 4.6 , the pins to be connected are
Arduino Digital Pins 24, 26, 28, 30, 32, 34 and 36.
FIGURE 4.6 Wiring diagram for the keypad.
In order to obtain a good global temperature estimate inside the chamber, four thermistors
are used in the Polar Bear. The circuit diagram for the thermistors is shown in Figure 4.7 . The
circuit shown in Figure 4.7 must be made for each thermistor. Connect the thermistor to the
Arduino 5 V output and a 10 kΩ as a voltage divider and then connect the other resistor's side
to the ground pin. A wire must be connected between the 10 kΩ resistor and the thermistor;
this wire will be connected to the Arduino Analog Pins. Each thermistor must be connected to
a single-analog pin; the pins are A 12 -A 15 .