# Timing Diagrams

Discussion in 'Electronic Basics' started by Ron J, Dec 7, 2005.

1. ### Ron JGuest

Happy Holidays!

Where can I find info on timing diagrams? I would like to learn them
because I am trying to learn PIC programming and also I2C bus, but I am
confuse with timing diagrams.

Any help?

Thanks!

2. ### PeteSGuest

Timing diagrams show the relationships required between various signals
(when in a datasheet) for something to work. There are specific timing
statements such as 'setup time' (the amount of time data must be stable
before an active clock edge) and 'hold time' (the amount of time a
signal must remain stable after a valid clock edge).

They really aren't difficult to understand at all.

Cheers

PeteS

3. ### Ron JGuest

Hello PeteS,

Thanks much for the kind reply! Do you know of a website with pictures
so I can understand more?

5. ### Ron JGuest

Hello,

I have that document and the timing diagrams are Greek to me -- for
now. For instance, I don't understand Figure 4 very well especially
when the timing diagrams "cross" each other. Can you explain?
Thanks!

6. ### Pooh BearGuest

Think of them as being like what you'd expect to see on a scope if you
probed the pins.

Graham

7. ### Pooh BearGuest

The 'cross' as you call it on SDA, the serial data line, indicates
where the data state is meant ' allowed to change ( if it needs to ).
See the text note underneath and the relationship to SCL, the serial
clock. I.e. data shouldn't change when SCL is high.

Graham

8. ### Rich GriseGuest

Well, it's a chart of what happens when. The X axis is time, as if you
were timing a race, and the Y axis is the states of various signals
along that time-line.

What part is it that you're having trouble with?

Thanks,
Rich

9. ### Jasen BettsGuest

Think of them as, a stack of a graphs of voltage against time
you'll need to use a fixed pitch font to read the rest of this
courier is a good choice.

_____ ____ ____ ____
\ / \/ \/
\________/\____/\____/

voltage ||voltage ||high||high|| high
is high ||is low || or || or ||
|| ||low ||low ||
|| || || ||
~~~~~~~~~~~~~~~~~~~~~~~~~~ voltage is changing (or not)

_____ ______
\ /
A \________/
| |
__________ <5ms
\
B \_____________

| | | |
voltage B stays high for atleast 10ms after voltage A goes low
voltage A stat low for atleast 20ms after voltage b goes low
the rise time on voltage A is less than 5ms.

Bye.
Jasen

10. ### Ron JGuest

Thanks, all! Thanks Jasen!

11. ### ehsjrGuest

Nice drawings!
Ed

<AOL>
Me, Too!
</AOL>
;-)