(r4) DevicesNeeded < AFNOG

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---+ 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:

<img alt="raspberry.png" height="351" src="%ATTACHURL%/raspberry.png" title="raspberry.png" width="494" />

It is better to use a plastic case for protection:

<img alt="case.png" height="181" src="%ATTACHURL%/case.png" title="case.png" width="254" />

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

<img alt="powerSupply.png" height="157" src="%ATTACHURL%/powerSupply.png" title="powerSupply.png" width="184" />

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

<img alt="sd.png" height="91" src="%ATTACHURL%/sd.png" title="sd.png" width="110" />

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 <i>cobbler </i>(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.

<img alt="cobbler.png" height="210" src="%ATTACHURL%/cobbler.png" title="cobbler.png" width="260" />

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

<table border="1" cellpadding="0" cellspacing="1" rules="none" style="height: 255px; width: 530px;"> <tbody> <tr> <td>

 <img alt="hc-sr04.png" height="176" src="%ATTACHURL%/hc-sr04.png" title="hc-sr04.png" width="246" />

 The HC-SR04 ultra-sonic distance sensor</td> <td>

 <img alt="" height="177" src="%ATTACHURL%/tcs3200.png" width="215" />

The TCS3200 colour sensor</td> </tr> </tbody> </table>

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.
| <p><img alt="" height="269" src="%ATTACHURL%/wires.png" width="227" /></p> <p>male-male bread board wires</p> | <p><img alt="" height="268" src="%ATTACHURL%/fm-wires.png" width="282" /></p> <p>male-female bread board wires</p> |

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.
| <p><img alt="" height="269" src="%ATTACHURL%/rgbLED.png" width="315" /></p> <p>simple rgb LED with common cathode<br />current limiting resistors on board</p> | <p><img alt="" height="273" src="%ATTACHURL%/lilyPad.png" width="290" /></p> <p>!LilyPad tri-color LED, common anode<br />current limiting resistors on board</p> |
 

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

<img alt="" height="250" src="%ATTACHURL%/levelConverter.png" width="355" />

-- %USERSIG{TWikiAdminUser - 2018-01-21}%

---++ Comments

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Attachments

Topic attachments
I	Attachment	History	Action	Size	Date	Who
png	GY-31.png	r1	manage	76.3 K	2018-03-07 - 17:05	UliRaich
png	case.png	r1	manage	42.1 K	2018-01-21 - 16:21	TWikiAdminUser
png	cobbler.png	r1	manage	42.4 K	2018-01-21 - 16:21	TWikiAdminUser
png	colorSensor.png	r1	manage	50.0 K	2018-01-21 - 16:15	TWikiAdminUser
png	fm-wires.png	r1	manage	196.1 K	2018-02-08 - 12:08	UliRaich
png	hc-sr04.png	r1	manage	50.9 K	2018-01-21 - 16:15	TWikiAdminUser
png	levelConverter.png	r1	manage	55.9 K	2018-02-08 - 11:50	UliRaich
png	lilyPad.png	r1	manage	152.8 K	2018-03-07 - 17:10	UliRaich
png	powerSupply.png	r1	manage	28.8 K	2018-01-21 - 16:21	TWikiAdminUser
png	raspberry.png	r1	manage	229.6 K	2018-01-21 - 16:15	TWikiAdminUser
png	rgbLED-1.png	r1	manage	128.6 K	2018-03-06 - 13:13	UliRaich
png	rgbLED.png	r1	manage	153.9 K	2018-02-08 - 11:50	UliRaich
png	rgbLED_smd.png	r1	manage	144.1 K	2018-03-06 - 13:13	UliRaich
png	sd.png	r1	manage	10.3 K	2018-01-21 - 16:21	TWikiAdminUser
png	tcs3200.png	r2 r1	manage	199.3 K	2018-03-06 - 13:13	UliRaich
png	wires.png	r1	manage	109.3 K	2018-01-21 - 16:21	TWikiAdminUser

Topic revision: r4 - 2018-03-07 - UliRaich