Button matrix 3 lines 4 colums (3x4)

[ReiLoko4]

How i know exactly button as pressed?

[jimmo]

hi @ReiLoko4 we're going to need a lot more info please. Do you already have the circuit wired up (or a pre-build keypad module?).

[ReiLoko4]

Yes, the hardware looks good, but, I don't know how programing this
3 lines, Pin in
4 colums, Pin out

I just know the value in the lines

[ReiLoko4]

COnfigure the three rows as output pins (i.e. p = machine.Pin(N, mode=machine.Pin.OUT), and the four columns as input pins (mode=machine.Pin.IN).

You scan your row pins (i.e. turn each one high in turn while the others are low), then for each row, read from each of the column pins.

Its works ? In my board in the rows have resistors and in the colums capacitors

//sorry for my bad english

[jimmo]

Please tell us more info. Maybe a schematic or at least a photo or a link to something with information about how it's wired up.

[ReiLoko4]

Please tell us more info. Maybe a schematic or at least a photo or a link to something with information about how it's wired up.

The original project

L1,l2 and l3 = rows
C1 etc = colums

[jimmo]

In my board in the rows have resistors and in the colums capacitors

These are diodes not capacitors.

So you need to scan the columns and read the rows. i.e. turn on 22, 21, 20, 19 one at a time while the rest are off, and then for each, read from 18, 17, 16.

[LudoJoris]

Hi,

Can't help you with the Pico, but did a 3x4 button remote controller for the micro:bit.
Here is part of the MicroPython code. It works exactly the way @jimmo replied.

from microbit import *

cols = pin0, pin1, pin2
rows = pin8, pin12, pin14, pin16

cmds = (
  ('+', '0', '-'),
  ('7', '8', '9'),
  ('4', '5', '6'),
  ('1', '2', '3'),
)

for pin in rows + cols:
    pin.write_digital(0)

cmd = None

while True:
    for r, row in enumerate(rows):
        row.write_digital(1)
        for c, col in enumerate(cols):
            if col.read_digital():
                cmd = cmds[r][c]
                break
        row.write_digital(0)
        if cmd:
            break

    if cmd:
        radio.send(cmd)
        cmd = None

[ReiLoko4]

Thx for the help, but I got the result with while
Turn on energy of coluns and read rows
But turn on just one colun and turn off other 3 (1 on, 3 off)

Sorry for my bad english bro 🥵

[PsuFan]

Seems way easier to add a GPIO expander...?

https://github.com/mcauser/micropython-mcp23017