input from keypad and microcontroller
Hi all,😁
can you guys help me with: how to input a value from a keypad (say a keypad having 4 numbers; 1,2,3 and 4) into a microcontroller and the latter reads the number entered?
e.g. i want the microcontroller to know that my system must shutdown when the bump sensor reads '2', i.e it hits something twice. So when i pressed the key '2', the microcontroller gets the value '2' and will compare it with the bump count. But i don't know how to do it.😕
i am thinking of using 4 different switches, each defining numbers 1 to 4. but this would occupy 4 ports.. so guys can this be done using ONLY ONE PORT? 😒
please reply soon.
regards,
Satanas
can you guys help me with: how to input a value from a keypad (say a keypad having 4 numbers; 1,2,3 and 4) into a microcontroller and the latter reads the number entered?
e.g. i want the microcontroller to know that my system must shutdown when the bump sensor reads '2', i.e it hits something twice. So when i pressed the key '2', the microcontroller gets the value '2' and will compare it with the bump count. But i don't know how to do it.😕
i am thinking of using 4 different switches, each defining numbers 1 to 4. but this would occupy 4 ports.. so guys can this be done using ONLY ONE PORT? 😒
please reply soon.
regards,
Satanas
Replies
-
reachrkataSure can. You can do it with a single ADC port.
Connect the ADC port to the supply via a 47k pull-up (say).
Next, connect different pull-downs to the same port through the 4 keys.
For example, Connect the ADC port to GND via a 1K and Key 1.
Again connect the ADC port to GND via a 2K and Key 2.... and so on.
When no key is pressed, the ADC detects Vcc. When Key 1 is pressed, the ADC detects the voltage due to potential divide of 47k and 1k.
..... and so on.
-Karthik.
-
satanasHi Karthik,
thanks for the tip.. i will try it right away..
cheerz.
regards.
satanas -
satanasHi,
i tried it but things are not working.. can you provide me with the circuit please-resistors values? the supply is 5V and am sure i did something wrong.. so please help me.. i have limited time. i would be very grateful to you guys..
regards,
satanas -
reachrkataPerhaps this clarifies everything -
![[IMG]](proxy.php?image=http%3A%2F%2Fimg99.imageshack.us%2Fimg99%2F7604%2Fanalogkeydetection.gif&hash=cbe741ea590b2e0f8edf64956baf58cb)
-Karthik
😁 -
Ashraf HZIn all honesty, I never thought of that kind of approach before 😛
-
reachrkataNo sweat Ash !! i too learnt it only in my company !!!
-Karthik
😁
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