> Hi again! > So I tried to load the following modules: i2c_core, i2c_algo_bit, > i2c_pport, i2c_dev, i2c_sensor, pcf8574. > Should I be able to se my pcf8574 chip that is hooked up on my parallel > port now? Cause I can not! Do I have to consider cables (length and > others) or have I done anything else wrong? Some hints on trouble shooting > would be apreciated. Hello I used cables like 2 meters but I think they can have much more. As for trouble shooting. You can try if the driver can force the lines to 0 and 1 so you know it is not "stuck". This can be done via kernel module parameter for i2c-algobit. Just do: modinfo i2c-algobit (or i2c-algo-bit) There is the parameter called bit_test Unload all modules modrobe i2c-algo-bit bit_test=1 modprobe i2c-pport watch the system log. If it says line is stuck, something with the parport is wrong.Double check that you have iobase 0x378 in bios and it is set to "standart" or SPP mode only. Also be sure no other drivers for parallel port got loaded Later you need to modprobe the pcf8574 this chip cant be detected so it must be forced. You can do: modprobe pcf7485 force=b,0x20,b,0x21 replace b with your bus number it will be zero if no other i2c-bus modules are loaded the 0x20 is first chip address 0x21 is second chip address. if you have only one just delete the second part. Then you can watch /sys/bus/i2c/devices/0-0020/read If you put zero to some PIN the value will change so likecommand: watch cat /sys/bus/i2c/devices/0-0020/read and with wire connecting some pins of chip to GND... Regards Rudolf
