i2c-pport and pcf8574

Mark D. Studebaker mds at paradyne.com
Sun Aug 24 19:17:13 CEST 2003


you may wish to put an oscilloscope on the  parallel port lines to see if it is working.
Also try modprobe i2c-algo-bit debug=1 to get some debugging printks.

Oliver Joa wrote:
> hi,
> 
> i want to use the i2c-pport driver to control some pcf8574. i have wired
> the pcf8574 to the parallel-port and connected 8 leds to the pcf8574 to
> show the status of the 8 bit outports. i have loaded the following
> modules:
> 
> debian:/home/olli# lsmod
> Module                  Size  Used by    Not tainted
> rtc                     5916   0  (unused)
> i2c-proc                6016   0  (unused)
> i2c-dev                 3776   0
> i2c-pport               1440   0
> i2c-algo-bit            7880   0  [i2c-pport]
> i2c-core               14464   0  [i2c-proc i2c-dev i2c-algo-bit]
> eepro100               18572   1  (autoclean)
> mii                     2288   0  (autoclean) [eepro100]
> 
> dmesg gives me the following:
> i2c-core.o: i2c core module version 2.8.0 (20030714)
> i2c-pport.o: i2c
> Primitive parallel port adapter module version 2.8.0
> (20030714)
> i2c-pport.o: found device at 0x378.
> i2c-dev.o: Registered 'Primitive Parallel port adaptor' as minor 0
> 
> when i make a:
> strace i2cset 0 0x20 0x0 1
> i get the following:
> 
> nanosleep({5, 0}, {5, 0})               = 0
> ioctl(3, 0x720, 0xbffffcf0)             = -1 EPERM (Operation not
> permitted)
> write(2, "Warning - write failed\n", 23Warning - write failed
> ) = 23
> ioctl(3, 0x720, 0xbffffcf0)             = -1 EPERM (Operation not
> permitted)
> write(2, "Warning - readback failed\n", 26Warning - readback failed
> ) = 26
> 
> debian:/home/olli# cat /dev/i2c-0
> cat: /dev/i2c-0: Remote I/O error
> 
> it seems that there is a i/o problem.
> 
> debian:/home/olli# cat /proc/bus/i2c
> i2c-0   i2c             Primitive Parallel port adaptor         Bit-shift
> algorithm
> debian:/home/olli# cat /proc/bus/i2c-0
> debian:/home/olli#
> 
> debian:/proc/sys/dev/sensors# ls -la
> total 0
> dr-xr-xr-x    2 root     root            0 Aug 10 19:15 .
> dr-xr-xr-x    5 root     root            0 Aug 10 19:15 ..
> -rw-r--r--    1 root     root            0 Aug 10 19:15 chips
> debian:/proc/sys/dev/sensors# cat chips
> debian:/proc/sys/dev/sensors#
> 
> an i2cdump 0 0x20 does not get any values from the chip.
> 
> do you have any idea why i can not get a connection to the chip?
> 
> thank
> 
> oliver joa
> 
> 



More information about the lm-sensors mailing list