pcf8583 rtc

[AGUERE]

Hello, this is my first time in this forum, sorry for my bad english.
I built the circuit with the pic16f877, i2c memorys, max 232,etc...all run ok, but I have a problem with the i2c rtc pcf8583 Philips, this real time clock no run, I tested the circuit and good all device, but when I put my hand in the circuit this rtc begin run ok, I tested again the circuit, I don,t see cold solder, bad contact,etc..only when i put my hand in the crystal 32768 Khz is run, but when I put off the hand don´t run. I change the crystal, change the chip, I solder the box crystal to ground, but impossible, don´t run. Please I need help me , I don´t Know wht happen in my circuit. Thank you very much

Carlos from Canarys Islands

[Darrel Taylor]

Did you include a capacitor from +5V to the OSCI input? What size is it?

I think it should be around 10pF

[AGUERE]

Thank you , for your reply. I built the circuit with the chip philips pcf8583, the pin 1 osc1, and the pin 2 osc0, I put the crystal 3.2760 and the pin 1 I put the capacitor 5-25 pf + 5 v, but I change the capacitor 22 pf, but nothing, I think is necesary programming the commands for running this chip. I programming only read date and time from pic, no write to new time, date. Please if you have diagram, or ex. this pcf8583 please send me. Thank you very much
Carlos from Canarys Islands

[Darrel Taylor]

Here are a couple of exaples using the PCF8583 from other

http://www.decadenet.com/pub/kashin.txt which is part of a video overlay project at http://www.decadenet.com/bob2/bob2.html

This one is actually for Proton+ so may be a liitle confusing, but it is similar enough to hlp.
http://users.picbasic.org/projects/D...ata_logger.htm