Mapping the Pinouts

There are two major issues with mapping a Raspberry Pi project to a Galileo (or any generic Arduino project): 1. Mapping the pinouts for consistency ; and 2. Software libraries for node.js or Arduino integration.

This post addresses the pinouts, software libraries will be detailed in a separate post.

For the AirGalileo project we performed an audit of the pinout requirements of the AirPi, then mapped them over to the Galileo platform.

ADC (MCP3008)

Used for analogue to digital conversion of: TGS2600 (AirQuality), MICS 2710 (NO2), MICS 5525 (CO), Light Detection Diode, and UVI-01 (UV Light detection).

ADC Pin Raspberry Pi Galileo Comment
1 3.3V 3.3V
2 3.3V 3.3V
3 GND GND
4 GPIO #18 GPIO #13 PCM Clock
5 GPIO #24 GPIO #3
6 GPIO #23 GPIO #4
7 GPIO #25 GPIO #5
8 GND GND
9-16 Used for sensor data input

Air Pressure / Temperature (BMP085)

BMP Pin Raspberry Pi Galileo Comment
SDA SDA0 SDA0
SCL SCL0 SCA0
VCC 3.3V 3.3V
GND GND GND

Temperature / Humidity (DHT22)

DHT22 Pin Raspberry Pi Galileo Comment
1 3.3V 3.3V
2 3.3V 3.3V via 10kΩ Resistor
2 GPIO #4 GPIO #2 Raspberry Pi GPIO #4 is a clock pinout.
3 Not used
4 GND GND

Light Detecting Diode

LDR Raspberry Pi Galileo Comment
. GND GND
. 3.3V 3.3V via 2.2kΩ Resistor to ADC Input #1

Ultraviolet Light Detection (UVI-01)

This uses the OpAmp one side of the UNI-01 component goes to GND. The resistors at pin 2 need to be a multiple of 470 from each other. No idea why.

OpAmp Raspberry Pi Galileo Comment
1 Not used
2 GND GND via 10k resistor
2 OpAmp Pin 6 via 4.7MΩ resistor
3 Not used
4 GND GND
5 Not used
6 To ADC Pin 4
7 5V 5V
8 Not used

AIR QUALITY (TGS2600)

TGS2600 Pin Raspberry Pi Galileo Comment
1 5V 5V
2 5V 5V
3 GND GND  via 22kΩ resistor
3 To ADC Pin 2

Carbon Monoxide (MiCS 5525)

MiCS 5525 Pin Raspberry Pi Galileo Comment
1 GND GND
2 GND GND  via 100Ω resistor
2  To ADC Pin 4
3 5V 5V via 3 resistors in series with total value of ~82Ω

Nitrogen DiOXIDE (MICS 2710)

MiCS 5525 Pin Raspberry Pi Galileo Comment
1 GND GND
2 GND GND  via 10kΩ resistor
3  To ADC Pin 3
3 3.3V 3.3V via 2 resistors in series with total value of ~66Ω
4 5V 5V

This results in a consolidated mapping of the following pins

Raspberry Pi Galileo Comments
3.3V 3.3V
5V 5V
GND GND We will ground the 3.3V and 5V circuits to different GND pins
SDA0 SDA
SCL0 SCL
GPIO #18 GPIO #13 This is the PCM Clock. Galileo #13 might not be correct.
GPIO #4 GPIO #2 This is the CPCLK0 on RPi. Does not appear to be used for clock function though, so can use any GPIO pin.
GPIO #23 GPIO #3 Not sure if this will make a difference, but GPIO #3, 5, & 6 on the Galileo are PWM pins.
GPIO #24 GPIO #5
GPIO #25 GPIO #6
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Mapping the Pinouts

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