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Remote style keypad — Parallax Forums

Remote style keypad

inakiinaki Posts: 262
edited 2006-08-22 15:38 in General Discussion
I need a keypad similar to a remote controller. I could hack a real TV remote but have found that they are totally integrated devices so are difficult to hack (no easy connectors to use). The standard keypads I have found are too poor for my needs.
What I want is the keys of a real remote but I want to generate my own IR codes. So a standard remote like the one Parallax sells would not match my needs.

I use a SX controller to generate the codes so I would use it also to scan the keyboard.

Do you know about any available solution (even if you know a hackable remote would be welcome)?

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Comments

  • willthiswork89willthiswork89 Posts: 359
    edited 2006-08-20 23:33
    Your Best bet would be to goto RadioShack and buy a bunch of pushbuttons and make your own along wih a 555 timer to do the dirty work.... thats what i would do or was doing at one point until i found RF lol

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  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2006-08-21 16:53
    I think that you would do better to take a BasicStamp and add an IR reciever to it. You can easilly adapt it to recieve and redeploy all the keys on a TV Remote controller.

    There is no need to break into the TV Remote and it is very good at what it does. So,inn that way, the TV Remote stays intact and you have tremendous flexiblity in how you choose to use it.

    There are two approaches to dointg this.
    1. Google for people who have alread done this and base your design on their code. The serial sequences are similar to RS-232, but often longer - like 12 bits instead of 8. In some cases, you can use partially recieved data and stay within an 8bit framework.

    2. Set up an IR reciever [noparse][[/noparse]one that has a 38500Hz filter] and an oscilloscope to capture exactly what each key code is as it is send.

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  • inakiinaki Posts: 262
    edited 2006-08-21 17:37
    Kramer, what I want is reproduce the codes accepted by a device that is standard, and I have not built it, so I cannot change the way the receiver behaves. I need to send the commands to that device with the precise format it supports. I do this currently with a simple scheme based on a SX28. What I want know is a decent keypad, something similar to a video tape remote would be fine.





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  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2006-08-22 15:38
    There are several ways to go, but basically there are two keypad configurations.
    You have to determine your hardware first.

    There is a 'grid' which for a 4x4 key pad would have 4 inputs and 4 outputs.
    That would have to be polled in an ISR in the SX. This would take 8 pins.

    Try www.sxlist.com for examples. Guenther's text also covering key pad input quite extensively.

    Then there is the 16 independent keys in a 4x4 key pad.
    You could have them encoded by combining to two parallel to serial shift registers and this would take about 3 pins I/O [noparse][[/noparse]Shift In, Chip Select, Serial Clock].

    The secod might be a bit slower, but keyed input doesn't really require speed. It too would require an ISR in the SX, but a different software approach.

    I am not sure that there are any examples of this in Assemby [noparse][[/noparse]you could use SX/B shiftin], but Jon Williams did this in a June 2000 Nuts and Volts article with a BasicStamp. The big advantage is a minimal approach to microprocessor I/O. I also suspect that the SHIFTIN routine may be a bit shorter.

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    "If you want more fiber, eat the package.· Not enough?· Eat the manual."········
    ···················· Tropical regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan

    Post Edited (Kramer) : 8/22/2006 7:09:33 PM GMT
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