mpr121 raspberry pi help

rhubarbdog76 — Tue, 02 Oct 2018 12:02:45 GMT

hi,

I've bought a 12 key keypad which has an mpr121 chip built in.

How do i read registers 0x00 and 0x01?

How do i signal that the rq line has been read and can reset to high/floating?

i've got this far with the dummy method `keypad.rq_high

this is my python

import RPi.GPIO as GPIO
import posix
from fcntl import ioctl
import time

IOCTL_I2C_SLAVE = 0x0703

class KEYPAD:

  def __init__(self, i2c, rq_pin, address = 0x5a):
    self._fd = posix.open('/dev/i2c-%d' % i2c, posix.O_RDWR)
    ioctl(self._fd, IOCTL_I2C_SLAVE, address)

self._rq_pin=rq_pin
GPIO.setup(self._rq_pin, GPIO.IN, GPIO.PUD_UP)

self.switch_on()

def _del_(self):
posix.close(self._fd)

def switch_on(self):
posix.write(self._fd, b'\x5e\x01')

def rq_high(self):
return GPIO.input(self._rq_pin) == GPIO.HIGH

GPIO.setmode(GPIO.BCM)

keypad=KEYPAD(1, 23)

try:

  while True:
    if keypad.rq_high():
      print("high", end = '\r')
    else:
      print("low ", end = '\r')

time.sleep(0.01)

except KeyboardInterrupt:
pass

print("")
GPIO.cleanup()

I only have switched on a few keys but realise i need to write something different to register 0x5e (probably 0x3f)

Re: mpr121 raspberry pi help

TomasVaverka — Thu, 04 Oct 2018 10:36:26 GMT

Hi Phil,

As you can see in the PCN16772, the MPR121 is a discontinued product and NXP no longer supports it.

However, attached you can find design guidelines including the sample code which might be helpful for your evaluation.

Best regards,

Tomas

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mpr121 raspberry pi help

Re: mpr121 raspberry pi help