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wiki:v2:hooking_up_pixy_to_a_microcontroller_-28like_an_arduino-29

Hooking up Pixy to a Microcontroller (like an Arduino)

Pixy is meant to talk to a microcontroller.

Out of the box, Pixy2 is ready to talk to an Arduino. It sends block information to Arduino at 1 Mbits/second, which means Pixy can send more than 6000 detected objects per second or 100 detected objects per frame (Pixy can process 60 frames per second.)

OK, to get Pixy and Arduino talking to each other, use the supplied Arduino cable to connect Pixy to your Arduino.

Note: if you're using Arduino Nano, the ribbon cable faces the interior of the Nano, it doesn't exit off the side like on the Uno (pictured).
If the cable is plugged in backwards, you won't be able to upload to the Nano, or have serial communication with it.

ce5166e65a245cce097741efef288fe09b08da8a.jpg

Next, download the latest Arduino library “arduino_pixy2-x.y.z.zip” here. Bring up the Arduino IDE and import the Pixy library by selecting Sketch➜Include Library➜Add .ZIP Library… (or if you're using an older version Sketch➜Import Library) in the Arduino IDE, and then browsing to the Arduino zip file that you just downloaded.

Next, load the “ccc_hello_world” example by selecting it in File➜Examples➜Pixy2. Upload it and bring up the Serial Monitor. You should see messages printed that look similar to this:

Detected 1
  block 0: sig: 1 x: 160 y: 111 width: 140 height: 135 index: 38 age: 42
Detected 1
  block 0: sig: 1 x: 160 y: 112 width: 140 height: 136 index: 38 age: 43
Detected 1
  block 0: sig: 1 x: 160 y: 111 width: 140 height: 136 index: 38 age: 44
Detected 1
  block 0: sig: 1 x: 160 y: 111 width: 140 height: 135 index: 38 age: 45
Detected 1
  block 0: sig: 1 x: 162 y: 109 width: 140 height: 133 index: 38 age: 46
Detected 1
  block 0: sig: 1 x: 162 y: 109 width: 140 height: 135 index: 38 age: 47
...

Note, this example will only print messages if Pixy is running the “color_connected_components” program and an object that matches one of its color signatures is visible. This is what PixyMon looks like when Pixy is running the color_connected_components program and it has detected objects:

Arduino API

Using Pixy with Arduino is really simple. You simply include the SPI and Pixy headers:

#include <Pixy2.h>

And make a global instance of Pixy by putting this little guy outside your setup() and loop() functions:

Pixy2 pixy;

The most important method in the Arduino library is getBlocks(), which returns the number of objects Pixy has detected. You can then look in the pixy.ccc.blocks[] array for information about each detected object (one array member for each detected object.) Each array member (i) contains the following fields:

  • pixy.ccc.blocks[i].m_signature The signature number of the detected object (1-7 for normal signatures)
  • pixy.ccc.blocks[i].m_x The x location of the center of the detected object (0 to 316)
  • pixy.ccc.blocks[i].m_y The y location of the center of the detected object (0 to 208)
  • pixy.ccc.blocks[i].m_width The width of the detected object (1 to 316)
  • pixy.ccc.blocks[i].m_height The height of the detected object (1 to 208)
  • pixy.ccc.blocks[i].m_angle The angle of the object detected object if the detected object is a color code (-180 to 180).
  • pixy.ccc.blocks[i].m_index The tracking index of the block
  • pixy.ccc.blocks[i].m_age The number of frames the block has been tracked.
  • pixy.ccc.blocks[i].print() A member function that prints the detected object information to the serial port

So it's simple to talk to Pixy2 with your Arduino! For more information on the Arduino Library and API, go here.

Updating Pixy Library for Arduino

Before installing a new version of the Arduino Library, it's recommended that you delete the existing library. To do this, you can go into your C:\Users\<yourname>\Documents\Arduino\libraries (or similar directory, <yourname>/Documents/Arduino in OSX and Linux) and remove the Pixy2 directory. Then re-run the Arduino IDE.

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wiki/v2/hooking_up_pixy_to_a_microcontroller_-28like_an_arduino-29.txt · Last modified: 2018/06/18 19:20 by jfrench