RTC and millis

Projects Programming
1

I've got a problem where my DS1307 RTC I2C data gets 'contaminated' with other serial data coming in on the RX pin on my Arduino Pro Mini 328.

So when I look at the serial monitor I get (h:m:s DoM/M/YY DoW)

11:24:6 5/3/14 6
11:24:6 5/3/14 6
45:27:6 165/165/165 165
11:24:6 5/3/14 6
11:24:6 5/3/14 6
18:40:3 108/28/90 128
11:24:42 5/3/14 6
11:24:42 5/3/14 6

Is there a way of calling the RTC once to a variable then using millis() to update that time variable?
void setup ()
{
time_var = RTC.now ;
}
void loop()
{
time_var = time_var + (millis() / 1000);
display.print(time_var);
}
or something?

2

or something?

Or something, yes. Post your code. There should be no corruption of the read from the RTC from serial data arriving.

The Time library does just what you suggest, periodically syncing with the RTC to keep time accurate. But, it shouldn't be necessary.

3

Unless you omitted the pull-up resistors on the I2C bus the problem
is almost certainly in your code, not a hardware issue. As always
post all your code....

4

Use the time.h library with the rtc.

You're probably getting glitches because you're polling the rtc multiple times within a second.