Menno, You may want to look at your I2C routines. Here is why. I was just finishing up some code on a pcf8583 and a 12c671 and I ran into a weird problem. Everything worked fine at 5 volts but when the circuit was switched to 3volt battery (the target voltage) I could no longer read the pcf8583. A 24lc64 also on the I2C bus could be accessed with no problem. The PCF8583 was rated down to 2.5 volt, and I could not for the life of me figure out what was going on. Started looking at the I2C signal on the DSO and started seeing some contention. There seems to be certain conditions on the I2C bus involving the ACK phase where the PIC is driving the SDA line hi when the PCF8583 is trying to drive it low. They were able to muscle it out at 5 volts, but at 3 volts there were problems. All the problems went away when I put a series resister (~330ohm) on the SDA line from the PIC. I also rewrote the I2C routines so that the pic never drives the SDA line high, but tristates SDA and lets the pullup pull the the line hi. I've not tested the circuit again to see if I can take out that series resister. Hope these tech ramblings were of some help. At 09:49 PM 9/29/1999, you wrote: >Hi everyone... > >I'm currently trying to get a PCF8583 realtime clock running and are having >some difficulty. I use a PIC16C84 to emulate the I2C bus. There is nothing >wrong with the I2C procedures since I also use them to access other I2C >devices on the same bus. I want the clock to give me an interrupt every 6 >minutes. It seems that whenever I read from the clock IC via I2C it doesn't >accept any other commands. It just hangs!!!. Please, can you help me? Maybe >there is something wrong with the datasheet and maybe I just missed >something? > >Thanx for any help > >Menno J Houtman carl -------------------------------------------------------- Henry Carl Ott N2RVQ carlott@interport.net http://www.interport.net/~carlott/ -------------------------------------------------------- You're entitled to your own opinions. You are not entitled to your own facts.