Devices needed

The Raspberry Pi

The Raspberry Pi features

• SoC: Broadcom BCM2837
• CPU: Quad Core ARM Cortex-A53, 1.2 GHz
• RAM: 1GB LPDDR2 (900 MHz)
• Networking: 10/100 Ethernet, 2.4 GHz 802.11n WiFi
• Storage: micro SD
• Ports: HDMI, 4*USB2.0, Ethernet, Camera, Serial Interface, Display Interface

Here is a photo of the processor card:

It is better to use a plastic case for protection:

In addition to the processor board itself we need a 5V, 2.5 A power supply with micro USB connector

and a micro SD card for storage. This card will hold the operating system and all the user and system files.

In order to access external devices like our sensors a series of interfaces are available:

• general purpose I/O pins (GPIO)
• standard tx,rx serial interface
• I2C instrumentation bus
• SPI interface

These interface pins are available on a 40 pin flat cable connector and are made accessible to the experimenter on a bread board through the cobbler (the red PCB with the 40 pin flat cable connector). In contrast to the photo a longer breadboard must be used in order to have enough space for the sensors.

Now, all we need in addition are the sensors themselves and some connecting cables:

The HC-SR04 ultra-sonic distance sensor

The TCS3200 colour sensor

Most of the bread board wires will be male-male, however a few male-female wires are also needed to connect the TCS3200. I bent one row of pins such that they can easily be inserted into the bread board making the TCS3200 board stand vertically. In this case we need the male-female wires to connect the upper row of pins with the bread board.

male-male bread board wires

male-female bread board wires

Even though not strictly necessary for the final project we will also use an RGB LED. This will be used in an intermediate step where we will display the color read from the TCS3200 color sensor on this RGB LED.

simple rgb LED with common cathode current limiting resistors on board

!LilyPad tri-color LED, common anode current limiting resistors on board

Since the Raspberry Pi GPIOs all work on 3.3V, the HC-SR04 as well as the TCS3200 however work with TTL (5V) logic, we need a level converter to bring down the sensor signal levels from 5V to 3.3V. This can be done either with a voltage divider using 2 resistors or with this level converter

-- TWiki Admin User - 2018-01-21

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