How to know oscillator frequency for HT12D and HT12E?

[sunnykpradeep]

I have used Ht12D and HT12E foe the encoading and decoading purpose .

https://www.engineersgarage.com/sites/default/files/HT12E_0.PDF
https://www.engineersgarage.com/sites/default/files/HT12D.PDF
these are the datasheets


I want know how to design oscillator for these i.e: taking R&C values for the frequency finding

The frequency of the encoader and the decoader , should same or not?
Hoe they are related?

 

[jpsganesh]

HT12E datasheet page no. 5 on the table
If u use ROSC=1.1MΩ it'll generate 3 KHz freq. (I used to use 1MΩ)
I think u can monitor the frequency of operation in OSC2 PIN (PIN no 15 in 18 PIN DIP) using oscilloscope. This is OSC OUT PIN.

Page no. 11 - OSC freq recommendation
The recommended oscillator frequency is fOSCD (decoder) ≈ 50 fOSCE (HT12E encoder)

HT12D datasheet page no. 3 on the table
If u use ROSC=51kΩ it'll generate 150KHz freq. (I used to use 47KΩ)

Ref page no 5 for "Oscillator frequency vs. supply voltage"

I hope it'll clear ur doubt. Still if u have any more doubt pls let me know.

 

[sunnykpradeep]

Sir,
From the datasheets
we have Rosc-en and Rosc-de
I want Cosc-en and Cosc-de valus and further want Fosc-en and Fosc-de values??
another question is, why they are not same i.e; frequencies??

 

[jpsganesh]

HT12E datasheet page no. 4
I hope u r going to use HT12E. If so look at OSCILLATOR1 block diagram from Approximate internal connections
Internally capacitor will be there. We can't change its value (I don't know that C value, pls let me know if anybody knows its value). So we can change R value only.



For Fosc value ref my previous post.

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why they are not same i.e; frequencies??

If they (HOLTEK) designed the internal architecture like that we can't do anything for that.
May be for decoding they might have needed more machine cycle than encoding. (50 times greater)

Page no. 11 - OSC freq recommendation
The recommended oscillator frequency is fOSCD (decoder) ≈ 50 fOSCE (HT12E encoder)

If anybody knows the exact answers for this pls let us know.