Hi Geert, I am just wondering about your "construction", because I am designing the schematic for my hardware. Can you please explain, why you use the 100 Ohm series resistors? Are they necessary or are they used for debugging purposes?
I have some doubts about pin 12 (EXT input). In the data sheet this pin has to be connected to either VSS or VDD. This input has high impedance. If you leave it open, strange things may occur. The signal level depends now on leakage current from the board and from the chip itself. In some instances it may result in a logical Low, in other circumstances it may be high. If this is the case, no A/D conversion will take place. Maybe this is the problem of gazoox22. For A/D conversion you need a clock, while you need no clock for D/A conversion. .................... Thomas Treyer Am 21.02.2007 um 19:00 schrieb Geert Vancompernolle: > --- In [email protected], "gazoox22" <[EMAIL PROTECTED]> wrote: > > > > Now, I tested the rewrite of the i2c kernel mode driver from > > http://www.gevawebsolutions.com/wiki/index.php? > title=FB_General_Issues > > The sample code is worth to try. But with the PCF8591 I can set the > > A/D converter, measured with a voltmeter. The D/A conversion doesn't > > work. Testet with and without pull up resistor. Sometimes the value > > differs from 0x00. What could be the problem? I can't visual the > > lines, because no osciloscope. > > > > Hi, > > First off, thanks for using the driver. > > Next, I don't understand you're not able to do the AD conversion. I'm > doing it without any problems (device is actually running now next to > me without giving one bit of a problem). > > The example code I wrote should give you the opportunity to do both AD > as well as DA. > > You're sure you have connected all the pins in a correct way? > > This is my "construction": > > Pin 1: to tap of potmeter > Pin 2: open > Pin 3: open > Pin 4: open > Pin 5: gnd > Pin 6: gnd > Pin 7: gnd > Pin 8: gnd > Pin 9: 100 ohm (series!) to SDA line of I2C bus > Pin 10: 100 ohm (series!) to SCL line of I2C bus > Pin 11: open > Pin 12: open > Pin 13: gnd > Pin 14: +Vcc > Pin 15: open > Pin 16: +Vcc > > Next to this, the other pins of the potmeter are connected to gnd and > +Vcc (3.3V). > > There's also a pull-up resistor of 5k6 to +Vcc on each I2C line. > > Best rgds, > > --Geert > > > [Non-text portions of this message have been removed]
