DS1307

jinggy · Joined: 20 May 2008 Posts: 9 Location: malaysia

hello all.

I tried the DS1307 driver from this link:
http://www.ccsinfo.com/forum/viewtopic.php?t=23255&highlight=ds1307

The only changes I made are as below:

ckielstra · Joined: 18 Mar 2004 Posts: 3680 Location: The Netherlands

The returned seconds are ranging from 0 to 59. Writing these to the LCD with a PUTC command means you are writing raw ASCII codes to the lcd, not readable text.

Try something like:

jinggy · Joined: 20 May 2008 Posts: 9 Location: malaysia

thanks ckielstra. it works perfectly now Smile

MegatroniC · Joined: 08 Dec 2009 Posts: 35

Hello,
I'm sorry I raised old theme.
I also use this driver.
My problem is: call function time_data() from main but I can not go back to main
or at least a few clicks of the button is obtained once.

Is it possible is the time delay?

Ttelmah · Joined: 11 Mar 2010 Posts: 19515

Have you got the pull up resistors on the two I2C lines?.
Without these, the I2C commands will hang, and never return...

Best Wishes

MegatroniC · Joined: 08 Dec 2009 Posts: 35

ckielstra · Joined: 18 Mar 2004 Posts: 3680 Location: The Netherlands

Don't connect SQW/OUT (pin 7) of the DS1307 directly to ground. This is an open collector output so probably nothing will be destroyed, but it makes no sense and you are wasting power. Remove the connection to ground and optionally you can get rid of R13 to save a component and a little bit power.

The problem of detecting multiple keys can not be caused by the 200ms delay, this is too short to press multiple keys.

How do you detect the keys? Is it interrupt based?
If possible post the routine for detecting the keys.

MegatroniC · Joined: 08 Dec 2009 Posts: 35

Thanks for the tips.

I think the problem comes from the delay and the method of detection of buttons.
But this delay is necessary for ds1307?
I try this:
if(counter>=xxx)
{
...
ds1307_get_time();
...
counter=0;
}
else counter++;

to avoid delay, but did not get.

I use this code for the buttons.

ckielstra · Joined: 18 Mar 2004 Posts: 3680 Location: The Netherlands

The delay is not required for the DS1307. You can leave it out if you want and should make no difference. I think the original author put it in to remove stress from the LCD; looping at maximum speed you could be doing thousands of display updates per second and the user most likely sees this as a flickering or dimmed display.
Why update at full speed if the clock only changes state every second?

The routine for scanning the keys works in the background based on a timer interrupt. This should be fine.

MegatroniC · Joined: 08 Dec 2009 Posts: 35

Here's part of it:

ckielstra · Joined: 18 Mar 2004 Posts: 3680 Location: The Netherlands

I'm not sure but it might have to do with the frequency you are scanning the switches. You reduced the scan period from 10ms to 30ms. A button is detected as being pressed when at least scanned 2 times. Worst case timing you press the switch just after a scan, resulting in a worst case of almost 90ms. This is slow, a quick button press can be gone by this time.

Then there is the effect of the mechanical switch contacts bouncing. When you press the switch it will not make a perfect contact at once, but vibrate a bit and make several contacts/breaks before settling. This process can take anytime from 1ms up to 50ms, depending on the switch.

For the above reasons I suggest you reduce the scan time from 30ms down again to 10ms as in the original switch.c version.

A second improvement is to reduce the 200ms delay in the display loop. As I said, you can remove the delay at all, but to prevent possible side effects on the display you could do something like this:

MegatroniC · Joined: 08 Dec 2009 Posts: 35

Тhanks for the advice ckielstra.

Will work on them.

Variables on the time and date I made them global, because I wanted to use them elsewhere. But if it's better to be local in this function will move there and will think of others in their place.

Again, many thanks.