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About Encoder/Decoder

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Hihi

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hello.. i got a question to ask abt encoder. i am using a HT12E that consist of 8 address bits and 4 data/address bits. If i want to expand the encoder so that there cld be more functions, say about 8 data bits, must i expand the address bits as well? or do any of u have recommandations on what encoder i should use? because i have searched the web on the various types of encoders but they all seem to have only 4 data bits. thanks alot. pls help...
 
Hihi said:
hello.. i got a question to ask abt encoder. i am using a HT12E that consist of 8 address bits and 4 data/address bits. If i want to expand the encoder so that there cld be more functions, say about 8 data bits, must i expand the address bits as well? or do any of u have recommandations on what encoder i should use? because i have searched the web on the various types of encoders but they all seem to have only 4 data bits. thanks alot. pls help...

I've not seen any either, but why not just make your own using PIC's or similar micro-controllers? - the Holtek devices are only pre-programmed micro-controllers anyway?.!
 
hi hihi, heh, thats funny.

i don't think there is a way to do what you want.
But how about this: say you have eight buttons. The eight buttons are all connected to one data pin, but each of the eight buttons is also connected to a different address pin. This will give you eight different outputs, with the same data pin.

Now do that for all four data pins, so that you have a couple of sets of four buttons, each set of buttons activates a different set of address pins.

So, you're using the same data pins with all the buttons, BUT each set of buttons connects to a different address, giving u a different output with each button. Do you catch my drift?

There is practically an infinite number of address combinations.

The downside of this is that you will have to have different decoders for each address :cry:
 
Hi HiHi,

You can devise a serial protocol and building it using a PIC as Nigel has suggested. All you need is a bit of programming.

If you would like to do it the hardware way, that's what I had done in the past.

I sent the 8-bit data in two go. As I can spare the special case of data value "F" which I can then use to signal to the decoder that a new pair of data is coming. You might not be able to do that if you need all 256 values in 8-bits.

Alternatively you can split your 8-bit data into two 4-bit data groups and applies them to the data input of the encoder one after another. You can do just that using a Quad 2-to-1 multiplexer ICs. You then feed the multiplexer select voltage to one of the encoder address lines. So the encoder would keep sending out 4-bit data with one address and another 4-bit data with different address.

You then use two decoders with corresponding addresses to get back the data.
 
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