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Remote control design problem with HT6221

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p55xp

Member
I am designing a ir-remote handset with 8 control keys for my own purpose.
It is working with default address.
Now I face a problem as I tried to use my CUSTOM ADDRESS.
The chip contains a mask rom, according to datasheet (attached) "The current value of ROM1 and ROM2 are both 00H"
My question is : how can I programm the mask rom in the HT6221? or, is it not programmable and the address can only be varied using diodes and resistors as shown in the datasheet application circuit?
 

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p55xp

Member
With high hope i am waiting for your suggestion, comment and/or judgement on the datasheet highlighted portion on page 5.

please do something
 

marcbarker

New Member
I clicked the pdf file, but it wouldn't open for me :(

You can't alter a mask rom program easily. They call it mask rom because it's programmed into the mask used to make the chip.

To alter the mask ROM you have to negotiate directly with the manufacturer of the IC, and ask them to change their mask, they literally make alterations to the design of the IC. You'll need to finance the change which could be over $50,000 just for a few ICs. It's OK if you're a big company like Sony or Toshiba, they can. You'd be better off finding another way than resort to changing the mask program. Really! :)

I hope this answered your question
 
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p55xp

Member
Thank you for the response.
I thought it can be programmed like an OTP device, because I have never seen a remote handset using diodes and resistors for customising the address. May be either they have incured the cost ($50,000 according to you) to change the mask or they are satisfied with the default address.
 

marcbarker

New Member
Holtek Taiwan often mention Mask ROM options in their datasheets, I believe that was the source of the confusion you had. It's a nice thought the chip is OTP, but alas, no! Entirely differernt technology!

The information about Mask Rom layer appearing in the datasheet isn't meant for the EndUser. For instance when Holtek make a new production run of Melody Generator ICs, the Client can specify a custom melody of his own to be programmed into the Mask Layer used during chip fabrication.

It would be interesting to learn how much it would cost to customise a run of HT6221s.
 

p55xp

Member
Thank you again, for applying your insight and thinking.
You are right, datasheet is the source of misconception and confusion in me.
Alas, my thought is wrong. But think if the address is that easily customisable (as I thought it was) the chip would have been more user friendly.
The chip could have gain good market too.
 
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