How Do You Connect Resistors in a Keypad Interface?

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Discussion Overview

The discussion revolves around the connections of resistors in a keypad interface, specifically in relation to a tutorial on interfacing keypads with microcontrollers. Participants seek circuit diagrams and clarification on how to connect resistors to differentiate between keypad switches.

Discussion Character

  • Technical explanation
  • Homework-related

Main Points Raised

  • One participant requests a circuit diagram for resistor connections to a keypad, referencing a specific tutorial.
  • Another participant reiterates the need for a diagram and specifies that the resistors pull the column lines high, likely to 5V or 3.3V, depending on the PIC power supply.
  • A third participant shares a link to a resource that includes a diagram showing resistors connected to the 5V line, suggesting it may be more intuitive.
  • A fourth participant provides another link, possibly offering additional information or diagrams related to the topic.

Areas of Agreement / Disagreement

Participants generally agree on the need for a circuit diagram and the function of the resistors, but there is no consensus on a specific diagram or solution provided in the discussion.

Contextual Notes

Participants have not provided specific assumptions or limitations regarding the circuit design, and the discussion does not clarify the exact resistor values or configurations needed.

smuscat
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Hi guys

Can please someone submit a circuit diagram for the resistors connections to the keypad of the below tutorial?
http://www.winpicprog.co.uk/pic_tutorial9.htm
"As the switches are all interconnected, we need a way to differentiate between the different ones - the four resistors on the interface board pull lines COL1 to COL4 high, these four lines are the ones which are read in the program. So in the absence of any switch been pressed these lines will all read high. The four ROW connections are connected to output pins, and if these are set high the switches will effectively do nothing - connecting a high level to a high level, results in a high level."
Thanks!
 
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smuscat said:
Hi guys

Can please someone submit a circuit diagram for the resistors connections to the keypad of the below tutorial?
http://www.winpicprog.co.uk/pic_tutorial9.htm
"As the switches are all interconnected, we need a way to differentiate between the different ones - the four resistors on the interface board pull lines COL1 to COL4 high, these four lines are the ones which are read in the program. So in the absence of any switch been pressed these lines will all read high. The four ROW connections are connected to output pins, and if these are set high the switches will effectively do nothing - connecting a high level to a high level, results in a high level."
Thanks!

They are just for resistors that pull the COL (column) lines high, probably to 5V or 3.3V, whatever the PIC power supply is.
 

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