Hi Friends, I am new to ARM. I have a project where i am trying to interface the keypad with controller. After a try of two days i thought i will try to take help from you guys....if somebody can refer me to any tutorial on this subject ...going to be a great help for me. I have tried to find any application note based on this but in a vain never found any thing after lot of googling. Guys please help me! Just guide me to some site where they have discussed any matrix keypad interfacing with LPC2148 or any other ARM controller.
Thank you!
LOL.
Google have thousands of descriptions of how to scan keypads. Must be hundreds of good descriptions.
And best of all - it doesn't matter what microcontroller, if we ignore microcontrollers that happens to have hardware-controlled keypad scanning.
After having isolated the code that sets pins and reads back states of pins, the code for scanning a keypad on a 8051 is just about identical to the code for an ARM or a MIPS or a PPC or a PIC or an AVR or a Z80.
So: 1) Learn the concept of how keypads are scanned. 2) Learn the relevance of debounce. 3) Learn the difference between handling single-key or multi-key presses. 4) Learn how _your_ processor configures processor pins. 5) Learn how _your_ processor sets processor pins. 6) Learn how _your_ processor reads back processor pins. 7) Learn how _your_ processor measures time (remember debounce?)
Combine, shake a bit and then test and release.
Don't see problems. See possibilities. This is a general exercise all schools have quite early in the microcontroller courses. That should be a hint that it is considered rather basic. I.e. not hard to learn. Not hard to do. And all the students are expected to manage the task on their own. Are you different from all the hundred thousands of students who does this exercise every year?
Thanks Per Westermark, I really appreciate your efforts! and thanks for this wonderful motivational speech.......thanks!