We are trying to make a line tracking robot. However, the route we are trying to follow is not so perfect with only black and white. I am wondering if we can adjust the sensitivity of the QTI sensor. Can anyone give me some advice? Please.
If you take a slightly different approach and place a 10K resistor across the RED and WHITE wire, you can use an external ADC as opposed to using the RCTIME function to detect the sensors response to the LED. The additional resistor basically bypasses the .01uF capacitor within the QTI sensor forming a voltage divider across QTI's sensor. Initially it might benefit to make this resistor adjustable to find the optimal setting, and then you can replace it with a fixed value.
Attached is modification that should work with RCTIME.... Allow twice as long for the Capacitor(s) to discharge, and expect higher returned values from the RCTIME command.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔ Beau Schwabe
IC Layout Engineer
Parallax, Inc.
Post Edited (Beau Schwabe (Parallax)) : 9/24/2008 5:11:33 PM GMT
Comments
If you take a slightly different approach and place a 10K resistor across the RED and WHITE wire, you can use an external ADC as opposed to using the RCTIME function to detect the sensors response to the LED. The additional resistor basically bypasses the .01uF capacitor within the QTI sensor forming a voltage divider across QTI's sensor. Initially it might benefit to make this resistor adjustable to find the optimal setting, and then you can replace it with a fixed value.
ADC:
http://www.parallax.com/Store/Components/IntegratedCircuits/InterfacingChips/tabid/613/CategoryID/78/List/0/SortField/0/Level/a/ProductID/232/Default.aspx
http://www.parallax.com/Portals/0/Downloads/docs/prod/appkit/ltc1298.pdf
Attached is modification that should work with RCTIME.... Allow twice as long for the Capacitor(s) to discharge, and expect higher returned values from the RCTIME command.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Beau Schwabe
IC Layout Engineer
Parallax, Inc.
Post Edited (Beau Schwabe (Parallax)) : 9/24/2008 5:11:33 PM GMT