ADC help
johnsrobotics
Posts: 26
Hello all. I have an ADC0831 chip (the one found in the Basic Analog and Digital text), and an OPT101 sensor from TI.
The datasheet for the OPT101 is here
http://wwww.ges.cz/sheet/o/opt101.pdf
I have wired the·OPT101 as seen in Figure 1
I have wired pin 5 to the ADC pin 2·as in the BAAD schematic instead of the pot.
I am using the sample code in the book. When connected with the pot, I see the changes. (I am Debugging the Binary and Decimal values)
When I remove the POT and wire the ADC pin2 to pin 5 (and 4) of the OPT101, I get nothing but zeros.
Do I need an additional op-amp before the ADC? Should I use a different ADC?
I am supplying the OPT101 with 5v from my Board of Education's VDD.
I am using a plain BS2.
The BAAD text can be seen here:
http://www.parallax.com/dl/docs/books/edu/baad.pdf
I have used a TSL230 from Parallax in the past, but I just got these OPT101's from TI, and would like to see them work.
Thank you for your time,
John Baker
The datasheet for the OPT101 is here
http://wwww.ges.cz/sheet/o/opt101.pdf
I have wired the·OPT101 as seen in Figure 1
I have wired pin 5 to the ADC pin 2·as in the BAAD schematic instead of the pot.
I am using the sample code in the book. When connected with the pot, I see the changes. (I am Debugging the Binary and Decimal values)
When I remove the POT and wire the ADC pin2 to pin 5 (and 4) of the OPT101, I get nothing but zeros.
Do I need an additional op-amp before the ADC? Should I use a different ADC?
I am supplying the OPT101 with 5v from my Board of Education's VDD.
I am using a plain BS2.
The BAAD text can be seen here:
http://www.parallax.com/dl/docs/books/edu/baad.pdf
I have used a TSL230 from Parallax in the past, but I just got these OPT101's from TI, and would like to see them work.
Thank you for your time,
John Baker
Comments
The part contains an op-amp, so you should not have to add one externally. The feedback pins are available so that you can incorporate feedback components suited to the light level you want to detect. Pin 4 provides a default 1 megaohm gain resistor.
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Tracy Allen
www.emesystems.com