EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: jayx on November 30, 2023, 10:13:22 pm
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I plan to build a sort of "inteligent storage" system. It supposed to detect if a small plastic container is in the slot or not. There will be about 100 containers in an array. I thought I can use an array of infrared proximity sensors on I2C bus for detection of the containers, but what I've found so far seems to be quite sophisticated with a distance measurement and over 100mm of range, or simple present/not present sensor, but without I2C. Maybe someone can suggest a specific component?
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I2C devices typically support a few addresses at most, often just 2, so 100 sensors isn't going to fly. This is probably an application for a multiplexed array of sensors.
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Or a few sensors pointing toward the front of the draws, with one IR LED per drawer. Turn on one LED at a time and the sensors can pickup where the object is base don time. Bit like how old light guns worked on Tube TV's.
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Old-skool would be microswitches with series diodes so they could be read individually, possibly in a 10x10 matrix, though for ease of coding it an 8x13 matrix would be preferable. Drive the 13 row line from two 74HC138 chips so only one goes low at a time, controlled by four output bits from a 16 bit I2C I/O expander (or direct from your MCU), and read out which switches are closed (low) from an eight bit input port with pullups on the same I/O expander( or your MCU).
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Thanks for the ideas. I thought about switches, but thought it wouldn't be very reliable solution. I've found some inexpensive sensor BROADCOM APDS-9930, but quickly found out that it has fixed I2C address! Then I've looked at other similar sensors, every one I've checked had fixed address :palm: I guess that's what MarkT meant, wondering what's the point of I2C then?
Anyway, today I've been printing some documents on a large office printer/scanner and noticed that the scanner has automatic paper size/orientation detector in the form of three sensors. I thought it's exactly what I was looking for, I'm tempted to take it appart to see how they are connected, would be surpriced if each one is on a separate I2C.