Remote style keypad
inaki
Posts: 262
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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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
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-Learn somthing about everything, and Everthing about somthing-
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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"If you want more fiber, eat the package.· Not enough?· Eat the manual."········
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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."········
Post Edited (Kramer) : 8/22/2006 7:09:33 PM GMT