How to interface PING sensor to AVR (ATmega168)?

XNOR

Hi,

How do I use the Parallax PING sensor with an AVR?
Specifically, the ATmega 168 using WinAVR (a gcc C-compiler and library).

The Parallax code uses the Serial commands of the Basic Stamp,
but I don't know how to implement this for the ATmega168.

I'm guessing this has been done before, but I couldn't find
a link that was simple enough for me to understand.
(It seems that many people did "bit-banging" using assembly language.)

Thanks for any help!

allanlane5

You send a PING sensor a pulse on the data pin, from 2 uSec to 5 uSec wide. You then 'listen' to the data pin (turn that pin to an input) and measure the size of the pulse that is returned on that pin. There's a 750 uSec delay from the end of the 5 uSec pulse to give your program time to 'set up' for the "size indication" pulse.

I assume the AVR has library code to generate a fixed size pulse, and another library call to measure a pulse-width on an input pin.

XNOR

Hi,··

Thanks for the reply, but I made a stupid mistake.····

I meant to ask about the Sharp IR distance sensor:··

http://www.parallax.com/dl/docs/prod/acc/SharpGP2D12Snrs.pdf

The code I'm having trouble with is the SHIFTIN command below:··

Read_GP2D12: 
   volts = 0                  'Reset Sensor Value 
   FOR index = 0 TO 2         'Read 3 Times 
      LOW Adc0831             'Enable ADC0831 
      [b][u]SHIFTIN[/u][/b] AdcData,AdcClock,MSBPOST,[noparse][[/noparse]result\9]  'Read The Voltage 
      HIGH Adc0831            'Disable ADC0831 
      volts = volts+result    'Add The Values 
      PAUSE 30 
   NEXT 
   volts = volts/3            'Average The Readings 
   RETURN 
 

How do I convert the SHIFTIN into C?·· ··

Thanks again for any help!· ··

··

Mike Green

That's a more complicated problem and one that doesn't involve any Parallax products, so it's really inappropriate for these support forums.

The ADC involved uses a protocol called SPI which is very common. Check the ADC manufacturer's website for datasheets and application notes. You may find a ready-to-go driver in C. Also check Atmel's website and support documents and you will probably find drivers in C for the ATmega168. The ADC datasheets usually include a detailed description of the signals necessary for doing an analog to digital conversion including diagrams of the signals involved.

Post Edited (Mike Green) : 7/2/2008 4:35:45 PM GMT

Franklin

Go here to start. The Arduino uses a atHega168 www.arduino.cc/playground/Main/ReadGp2d12Range

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