Shop OBEX P1 Docs P2 Docs Learn Events
Can ColorPAL measure light intensities like the TSL230R Light to Frequency Chip? — Parallax Forums

Can ColorPAL measure light intensities like the TSL230R Light to Frequency Chip?

roboticsrobotics Posts: 90
edited 2010-12-31 21:43 in Accessories
Hi,

Can the ColorPAL with it's integrated TAOS TSL13T Light-To-Voltage sensor measure light intensities like the Parallax TAOS TSL230R Light-To-Frequency Converter chip?

I am more interested in overall light intensity measurement than color determination. If possible this would be very useful as the ColorPAL has the RGB LEDS integrated along with the sensor.

Many thanks!

Comments

  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2010-12-31 09:57
    The ColorPAL can certainly be used to measure light intensity. Just command it to take an ambient light reading (i.e. with the LED completely off). One significant difference between it and the TSL230, though, is that the TSL13T does not enjoy the '230's much higher dynamic range. So be sure to compare their datasheets before making a buy decision.

    -Phil
  • roboticsrobotics Posts: 90
    edited 2010-12-31 17:50
    Hi Phil,

    Many thanks for your answer. Two questions please:

    1) I noted that the TSL230 has a spectral response of 350-1000nm, while the TSL13T has a spectral response of 320-1050nm. Are these figures the "dynamic range" that you mentioned?

    2) I have been working with the Parallax TSL230 (which I believe is the TSL230RP-LF) and have noted that whenever I perform a light reading such as a simple red LED in a black box, that the intensity reading continuously (ie, every 0.10 second) decreases a digit. This occurs when operating the Parallax spin demo code for the TSL230. Do you think it is hardware, software? I have tried many different LEDs and the same result occurs. Any ideas greatly appreciated as this is a consistent problem in trying to obtain stable readings.

    In advance, thank you!
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2010-12-31 21:08
    1) No. Dynamic range refers to the chip's ability to respond to very weak light intensities without saturating at the high end.

    2) I don't really know about this one, but here's a guess: If your LED is current-limited using a simple resistor, the resistor could be warming up and slightly increasing in resistance as a consequence, thus reducing the current available for the LED. Try using an LM317L instead of a resistor to regulate the current going to the LED. Also make sure that the TSL230 has a very clean and constant Vdd supply.

    -Phil
  • roboticsrobotics Posts: 90
    edited 2010-12-31 21:43
    Phil,

    I appreciate you taking the time to assist, thank you!
Sign In or Register to comment.