example code for DS1337

[jellis00]

Do you have a crystal with a capacitance load of 6pf? If not, the clock won't be very accurate.

I am ordering one with 6pf capacitance now...the one I have been using has 27pf capacitance and I still haven't been able to get the DS1337 to run no matter what CONTROL word I send it. Even wit %00000000, which is no alarms and 32.768kHa on the SQW output, I don't see anything on the SQW output pin or an indication that the clock is running. Frustrating! Hopefully with a LCD I will make some progress in the troubleshooting.

Yea it is kind hard to see if the RTC is working without a display. I have a serial LCD that I plug into my clock boards. The clocks run without the LCD but I only plug it in when I'm checking the times and testing the clock. I built a test program into it that lets me change the alarm times to one and two minutes from the current times and at the completion of the test it restores the alarm times to their normal settings and reboots the system. I've had 80 of them in service for almost 3 years now.

I just tried to get a picture of the board to send to you but the limits were exceded. If you send me your email address I'll send you a picture.

I am ordering a serial serial LCD (delivery in 2 weeks) to resolve the Pin conflicts in my EasyPic6 with the I2C interface (RB0/RB1) from the 18F4550 MCU. Your test program sounds very interesting. How do you initiate the MCU to run just the test program instead of the application program?...is it when you plug something into that the MCU senses like an external PC to MCU serial cable or a USB cable? I would like to consider doing something similar in our application. Would definitely like to see the photo you offer...send to my email at [email protected].

[Darrel Taylor]

John,

I'm not sure which pin you've connected SQW to, but ...

      TRISA =%00000000 
      TRISB =%00000000 
      TRISC =%00000000 
      TRISD =%00000000

One of the first things you do is set almost all the pins to output.
That would stop any signal from SQW.
<br>

[mackrackit]

If you think it is a capacitor issue and you are ordering more parts you may want to look at the DS1337C. Everything is built in.

What voltage are you running the RTC on?

[jellis00]

I'm not sure which pin you've connected SQW to, but ...
One of the first things you do is set almost all the pins to output.
That would stop any signal from SQW.
<br>

I seem to be having a lot of senior moments lately...this being another one. I should have caught that....once I set TRISB to provide for inputs on the pins I had connected to SQW/_INTB and _INTA the alarms worked as intended, thus indicating to me that current time and alarms were being correctly set at programming time even though I couldn't see that they were because of lack of a LCD.
Thanks again Darrel!