Pixy2 line following, no arduino

Burg · November 8, 2020, 11:58am

Hello,

Please help me understand the received data and determine the position of the line vector. My device uses the UART interface to communicate with pixy2. I am sending a getMainFeatures query for pixy: 0xc1ae, 0x30, 0x02, 0x00, 0x01.
Receives the answer as in the pictures below (according to the position of the lines in the picture):

According to the Line Tracking - Packet Reference:

For a more recent example, I understand it like this:
0xc1af - sync
0x31 - type of packet
0x08 - lenght of packet
0x9300 - sum of payloads bytes

the next data is a mystery…
Probably the data of x0, x1, y0, y1 - but I can’t calculate the vector’s position from this.

Can someone explain it to me? I need to calculate the position of the line vector from this data.

BR
Burg

edge · November 10, 2020, 1:04am

Hello,
Byte 6 is either a 1, 2, or a 4 depending on whether it’s Vector, Intersection or Barcode.

If it’s a 1, it’s a Vector and has the format like you’re guessing:
uint8_t m_x0
uint8_t m_y0
uint8_t m_x1
uint8_t m_y1
uint8_t m_index
uint8_t m_flags

The Arduino code might help also:

github.com

charmedlabs/pixy2/blob/master/src/host/arduino/libraries/Pixy2/Pixy2Line.h

//
// begin license header
//
// This file is part of Pixy CMUcam5 or "Pixy" for short
//
// All Pixy source code is provided under the terms of the
// GNU General Public License v2 (http://www.gnu.org/licenses/gpl-2.0.html).
// Those wishing to use Pixy source code, software and/or
// technologies under different licensing terms should contact us at
// [email protected]. Such licensing terms are available for
// all portions of the Pixy codebase presented here.
//
// end license header
//
// This file is for defining the Block struct and the Pixy template class version 2.
// (TPixy2).  TPixy takes a communication link as a template parameter so that 
// all communication modes (SPI, I2C and UART) can share the same code.  
//

#ifndef _PIXY2LINE_H

This file has been truncated. show original

Hope this helps!

Edward

Burg · November 11, 2020, 4:06pm

Hi Edward,

thank you for the information. I managed to get all the data and my robot follows the line

BR
Burg