Accessing the buttons

[bqpd]

Hi,
using the buttons in C works fine in general.
Is there any possibility to get an interrupt if any button gets pressed?
Is it also possible to get the button status in Python?
What SPI library is used?

Thanks for your time,
bqpd

(p.s: sorry for the bad english)

[strancara]

Hi,

from python, you can access the buttons like this:

Code: Select all

#!/usr/bin/python
import array, fcntl
from time import sleep
# test program to read state of buttons on HwLevel LCD display for Raspberry Pi
# 12 March 2014 - William B Phelps - wm@usa.net
# no warranty of any kind, use at your own risk

#SSD1289_GET_KEYS = -2147202303

_IOC_NRBITS   =  8
_IOC_TYPEBITS =  8
_IOC_SIZEBITS = 14
_IOC_DIRBITS  =  2

_IOC_DIRMASK    = (1 << _IOC_DIRBITS) - 1
_IOC_NRMASK     = (1 << _IOC_NRBITS) - 1
_IOC_TYPEMASK   = (1 << _IOC_TYPEBITS ) - 1

_IOC_NRSHIFT = 0
_IOC_TYPESHIFT = _IOC_NRSHIFT+_IOC_NRBITS
_IOC_SIZESHIFT = _IOC_TYPESHIFT+_IOC_TYPEBITS
_IOC_DIRSHIFT  = _IOC_SIZESHIFT+_IOC_SIZEBITS

_IOC_NONE = 0
_IOC_WRITE = 1
_IOC_READ = 2

def _IOC(dir, type, nr, size):
#  print 'dirshift {}, typeshift {}, nrshift {}, sizeshift {}'.format(_IOC_DIRSHIFT, _IOC_TYPESHIFT, _IOC_NRSHIFT, _IOC_SIZESHIFT)
  ioc = (dir << _IOC_DIRSHIFT ) | (type << _IOC_TYPESHIFT ) | (nr << _IOC_NRSHIFT ) | (size << _IOC_SIZESHIFT)
  if ioc > 2147483647: ioc -= 4294967296
  return ioc
#def _IO(type, nr):
#  return _IOC(_IOC_NONE,  type, nr, 0)
def _IOR(type,nr,size):
  return _IOC(_IOC_READ,  type, nr, size)
#def _IOW(type,nr,size):
#  return _IOC(_IOC_WRITE, type, nr, sizeof(size))

SSD1289_GET_KEYS = _IOR(ord('K'), 1, 4)
#print 'ssd {} {:12} {:0>8x} {:0>32b}'.format(ssd1289, hex(ssd1289), ssd1289, ssd1289)
buf = array.array('h',[0])

print 'HwLevel Button Test program - March 2014 by William Phelps'
print 'Press Top & Bottom buttons simultaneously to exit'

with open('/dev/fb1', 'rw') as fd:

  while True:
    fcntl.ioctl(fd, SSD1289_GET_KEYS, buf, 1) # read the key register
    keybits = 0b11111-buf[0] # invert so bits show key pressed
 
    if keybits:
      print 'buf {:0>8b}'.format(keybits)
      # there's probably a better way to do this ...
      buttons = (keybits & 0b10000 > 0, keybits & 0b01000 > 0, keybits & 0b00100 > 0, keybits & 0b00010 > 0, keybits & 0b00001 > 0)
      print buttons
      if buttons == (1,0,0,0,1): # exit if top and bottom buttons both pressed
        break

    sleep(0.1)


buttons do not trigger an interrupt. You can not use SPI directly since it would interfere with LCD transfers.

regards.

[bqpd]

Thank you very much for your quick reply - helped me a lot.
Best wishes,
bqpd