Society of Robots - Robot Forum
Electronics => Electronics => Topic started by: gizzerd91 on August 17, 2008, 11:12:21 AM
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I've been using this sensor: http://www.trossenrobotics.com/5i-Force-Sensing-Resistor-Kit.aspx, but I can only get a binary response out of it. I need it so thin, so I cant have thicker sensors. On the page is a video of a guy using it with a 256 level response. Maybe its my board. Ive been using a really simple kit board that's programmed with BASIC. What should I buy so that I can get multiple levels of response and have 30 I/O pins (I know, its super complicated). Specifically I need 18 Digital input ports, and 9 servo control ports. Maybe I just use a couple chips, but that would be tricky.
Anyways, that's kindof a long explanation. What does everyone else think?
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Please provide us with the code you used and a link to the board you are using
Welcome to the Forum!
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I'd have to go out to my gradpa's house to get that computer, but the board was one I took from a Boe-Bot kit, and the code was super simple. It just checked both the sensors, subtracted one from the other, and multiplied that by some number (I forget exacley what it was, but it was so I could get the correct voltages for servo control) and then sent that right to a servo. I have another question now. Would the Axon be good for what I'm trying to do here?
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it's an analog output, or so it seems from my scanning of the page.
are you sure you have the the output hooked up to an ADC? or do you have ADC software that you're using?
You may be getting a binary response because the pin is set as digital and thus can't tell the difference between 2.1v and 2.2v but can only tell if it's above 2.5v or below 2.5v. thus only giving you a 1 or a 0
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Do you have a multimeter around? Can you check on the output voltages your sensor gives? And what are ideally the voltages you'd like from the sensor?
Would the Axon be good for what I'm trying to do here?
the board was one I took from a Boe-Bot kit
What should I buy so that I can get multiple levels of response and have 30 I/O pins
I assume you are looking for 30 ADC (analog to digital converters). The Boe-Bot kit doesn't have real ADC, so it fakes it through some hardware tricks. You won't find 30 ADC in any microcontroller on the market that I'm aware of, only in the expensive professional DAQ boxes you can buy. The Axon [only] has 16 ADC . . . but you could buy two of them (cough :P) to get 32 ADC, and have them communicate to each other over a UART.
Specifically I need 18 Digital input ports, and 9 servo control ports
Digital sensors are off/on. It is possible to use your touch sensors with a digital input, however you'd need external hardware to get the output voltages to the required values. That Voltage Divider device in that link can probably do it, but if you need 18 of them that'll get a bit expensive too. Making your own will be like $5/each, but will take you a long time. If you just need digital inputs, the Axon has like 50+ of them.