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PIC C code and Comparator Hysteresis

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Luqman

Wed Aug 08 2007, 03:52AM

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Y does 9306 Serial EEPROM is interfaced with controllers? Is it good to interfaced it with PIC controllers?

Ajay

Wed Aug 08 2007, 04:26AM

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well selecting an EEPROM for your project is usually depends on your requirement, and also second point is the compatibility. Its not mandatory that you should use only one type of EEPROM. e.g. your project need a maximum data of 2Kb to store so, there is no point for you to use an EEPROM of 8Kb or something.. i hope you understand my point. So according to need of your project you can select EEPROM.

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Luqman

Mon Aug 20 2007, 05:12AM

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hi, ajay

There is a comparator module in PIC 16F877 how can i configure it or program it to achieve system hysteresis i.e. the stability(control) in on/off a device?

Ajay

Mon Aug 20 2007, 05:29AM

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you cannot achieve a perfect hysteresis in comparator. because minor fluctuations are always there. But i really don't know any other method to achieve hysteresis except taking averages. I have seen many projects (like digital thermometer etc.) where i have taken averages and its working pretty file. You can also define a particular limit upto which the o/p holds its stability.
e.g. define rage for a constant value.
say you want to have a value 5 for which switching is done.
so define a range. like.. from 3-7 or 4-6 as per your need and amount of fluctuation. This will help you control the switching and minor fluctuations will be neglected.

Also what you can have a high resolution comparator. That also will solve your purpose, but it will be a separate hardware.

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Luqman

Tue Aug 21 2007, 12:07AM

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would u brief me an example C code to define a specific range and amount of fluctuation.How can i get C code for digital thermometer from download section at the forum

Ajay

Tue Aug 21 2007, 02:37AM

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I have not posted the thermometer project yet.. but i will do it. soon...
instead of just using one if statement
like
if(dat<5)
switch something
else
switch something

A range can be specified something like this..
if(dat>6)
switch something
else if(dat<4)
switch something

so this way you have specified the switching range.. instead of just switching at 5 u are actually providing +/-1 limit to the switching.
I hope you have got it..

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Luqman

Wed Aug 22 2007, 11:21AM

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i've downloaded ur code at download section for 89C4051 as RTC as it is a software based RTC instead of interfacing external RTC IC's ,but i didn't understand it completely so i want to know that from where did u conceived the idea is there any resources(like tutorial) available on the net which help me to understand the software based RTC.

Ajay

Wed Aug 22 2007, 11:23AM

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well.. the only idea i had in mind was...
60 seconds = 1 min
60 min = 1hr
24 hr = 1 day
30/31/28 days = 1 month
12 months = 1 year

So i had this idea

using a for loop!! isn't that simple?

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Luqman

Thu Aug 23 2007, 02:31AM

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i read 89C4051 as RTC and only understand few functions with the help of commenst written in the code the remaining functions i did not understand would u give details of the code in a tutorial manner as u have done it in the LCD tutorial.

Ajay

Thu Aug 23 2007, 02:45AM

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its a biiiiggg.. code.. i cannot comment all of it... will look rubbish.. also it need time.. you can paste the part of code which u didn't understand, i will comment it here..

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