PDA

View Full Version : Questions about QTI Sensor ...



sealion99
12-14-2011, 04:13 AM
Does anyone have more information on the QTI sensor? Here's a few of the things I'd like to know:

1) What are the mounting options? Is the large hole in the board just a mounting hole or is that a ground connection?

2) What is the lowest voltage that can be used with this sensor? Would it work at 3.6V? I understand the timing characteristics would change (which is fine), but would it work?

3) What are the limits on measuring distance (i.e. how close/far must this be away from a surface to be measured)?

4) What is the shape of the IR beam? I need to mount this in some close quarters and am wondering about interference issues. Would it be possible to construct some type of Light shield to help focus the IR beam without interfering with its operation?

5) Could this be used to provide an incremental encoder for a motor?

6) Is it possible to extract any level of distance-to-target information from the output?

7) The write-up states that the sensor is capable of ANALOG and DIGITAL outputs. Since this appears to be working via a capacitor decay, which is ANALOG, where does the DIGITAL output come in?

If anyone has any experience with this sensor, please let me know.

Thanks,
Chris

SRLM
12-14-2011, 05:51 AM
1) The large hole is primarily for mounting. I do not know if it is grounded or not, but in any case one of the pins is ground.
2) I've used it just fine at 3.3v.
3) IIRC it must be used very close to the surface (up to maybe 1cm away)
4) You can add a tube around the sensor to prevent interference, but I've used them as is side by side with a surface about 5 mm away with no cross interference.
5) Yes, assuming you have a black and white encoder disk attached to a shaft to measure.
6) Not that I've seen.
7) The digital assumption comes from assuming that when a pin is sample for digital input, all analog values higher than some threshold voltage will be considered a 1, and the rest a 0. It depends on your microcontroller as well.

sealion99
12-14-2011, 02:45 PM
Couldn't have gotten a better set of answers!! Thank you very much for the information.