Andy

Question

First time using this so hoping someone can help and I'm explaining it well enough but I'm wanting to make a project for work - the idea being to easily locate an item on a shelf using LED lights. I will be using a standard keypad input that converts that input to a single 8 digit number, using a SIPO shift register. I'm struggling on the next part, which is then trying to match that number with some sort of modifiable database list that is numbered 1 to 100 (it has to be modifiable due to the fact I need to update the number manually myself as it will/can change everyday). The plan would be, if the keypad matches to one of these numbers it would turn on the corresponding LED that is located on the shelf. 
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fmilburn · Answer

Hi Andy,

Another method that might work for you is to use individually addressable LED strings (not strips) sometimes called Neopixels. See for example: https://hackaday.com/2020/01/26/light-the-way-to-every-component/

beacon_dave · Answer

So basically you have 100 locations on the shelf each lit with a LED, and each item placed on the shelf has been tagged with a 8 digit code ? You could create a 100 element array which holds your 8 digit codes for the day. Loop through the array to see if the current number entered matches any value in the array and if so use the array index number to light the LED. https://www.arduino.cc/reference/en/language/variables/data-types/array/ Note that the arrays are zero-indexed so it would be 0-99 and not 1-100, so you need to subtract / add 1 accordingly or may want to create a 101 element array (0-100) and ignore the first element. Or renumber your shelf 0-99. Updating the 'database' would be just a case of selecting the index position in the array and storing a new 8-digit value. Need to consider if you can ever have two or more 8-digit numbers at the same time and how you want to handle that. Also need to consider if you want to store this data to EEPROM or SD card so as you don't lose it after a power cycle.

shabaz · Answer

Hi Andy, You could (if desired) split this project into two pieces (or more). Once piece is the mapping from your source number to your destination number. The second piece is using the destination number to light up an LED. The reason it could be interesting to split it, is so that you could focus on the first piece which is usable standalone anyway, if (say) the shelves or locations already have written labels 1-100. Piece 1 immediately provides usable functionality if people can read the destination location once they enter the source number. (It could be read from a computer screen or LCD screen or an LED display for instance, it's up to you). If you're going to have to update things daily, then it could be worth spending the effort streamlining or really making this first piece easy-to-use so that yourself or any delegate you assign can do this task daily. For example, you may choose to do it via a web browser page,so that anyone that you want to, can log in and update the hundred entries daily. Once people are pleased with that portion of the system working well, then you could consider how to convert the output into LED indication, e.g. using Arduino and Neopixel etc. Or people may want you to expand it to cover more shelves or a different location too, etc. Anyway, this is just an idea.

Andy

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