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I am designing 8*8 reed switch matrix which will be connected to Arduino. I am using Arduino Duemilanove. I have completed the matrix portion but don't know how to connect and where to connect the other elements. My Matrix circuit

I decided to use the following items:

  • Arduino (Duemilanove)
  • 64x Reed Switch
  • 64x Diode (1N4148)
  • 20x Resistors (10K)
  • 1x 74HC595
  • 1x 74HC165

I dont know where to place the Resistors and shift Registers and connection from shift registers to arduino. I need help in the circuit diagram. Please help me out with the circuit diagram.

Reference: https://mtifall10.wordpress.com/2010/12/10/magnetic-sensing-chessboard/

Aman Sinha
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2 Answers2

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I'd use something like that:

enter image description here

Where LOAD should be in HIGH state by default, LOW level loads inputs on 74HC165, and LOW to HIGH change loads outputs.

So you just send short LOW pulse to the LOAD, and then send next row to scan (will be loaded in next round) to the SPI. You have to remember the previous row or you have to connect QH* output from 595 to SER on 165 and shift out two bytes, one dummy and second will be the new row to be scanned.

And the matrix scanning is Active LOW. So you have to send the byte with one bit cleared (selected row) and rest bits set. And it's similar for reads (but you can use inverted output from 165 as well to get inverted values directly).

KIIV
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I'm not an expert but I'll try my best. I can't assure you that this is 100% correct.

Because of the limited amount of digital ports you will also have to use the analog ports.. In your case, the a, b, c, d... pins are "positive"(current goes from plus to minus). The pins 1, 2, 3... are your grounds/negative side.

The resistors should be connected to each positive pin, in your case pin a, b, c and so on.

EDIT: Sorry, I did bit consider the shift register. You will have to read the datasheet. You'll probably use a port with pulse width modulation(PWM), GND port and VoltageOut port.

Micropop
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