I am going to interface..keypad with 89c51...my problem is my port pins are alredy uesd for diffrent purpose icant change the configuration...i need a key pad that produce serial output or RS232 compatible output....Is there any dedicated keypad encoder IC available in market that produce rs 232 compatible output...
Re: Pls help me..........this is secondtime i am posting thi
One option is to "create" such an IC by yourself ..
Take, for example, PICAXE microcontroller .. It has several general purpose I/O pins and RS-232 TX and RX pins ..
Here is an example of a KEYPAD lock based on PICAXE microcontroller .. https://smendes.com/el31p/KeypadLock.pdf
With just slight modifications it can read keypad and transmit data through serial port, and it can perform this task THE WAY YOU WANT ..
Re: Pls help me..........this is secondtime i am posting thi
IanP said:
One option is to "create" such an IC by yourself ..
Take, for example, PICAXE microcontroller .. It has several general purpose I/O pins and RS-232 TX and RX pins ..
Here is an example of a KEYPAD lock based on PICAXE microcontroller .. https://smendes.com/el31p/KeypadLock.pdf
With just slight modifications it can read keypad and transmit data through serial port, and it can perform this task THE WAY YOU WANT ..
Re: Pls help me..........this is secondtime i am posting thi
Not that I am aware of ..
There is Keypad IC, namely the 74C922, but it doesn't have serial port and has to be read by a microcontroller through 4-bit data + control signals port .. https://www.elexp.com/tips/74C922.pdf
So, from that point of view option with PICAXE microcontroller can be very tempting ..
Re: Pls help me..........this is secondtime i am posting thi
Hel0
vibeesh
There is way to do with SINGLE port line try this one,
But u have to dedicate one interrupt line.
This techniqu is basically pulse width modulation.