8051+keypad+NVRAM+LCD+RTC

[boedyoe]

How to connect keypad+NVRAM+LCD+RTC to 8051? Parallel NVRAM connect to port 0 and port 2. The 16x2 LCD is connected to port 1. How to expand port to connect keypad and RTC?

 

[SphinX]

Salam,

Use Shift Registers (serial in parallel out)
You can use 74HC595 for this purpose.

Bye

 

[sadat007]

Use I2C RTC and I2C I/O expander for access KeyBoard.

 

[ZeleC]

Why dont u use expanded mode??

 

[engraxate]

very very easy
just use i/o mapped memory hardware

 

[fireplus]

hi,
you can use the 4 bit mode of the lcd (you will need 6 i/o only) for lcd

bye

Fire in the Wire :sm2:

 

[boedyoe]

Can anyone give schematic hardware diagram and software listing? I'm newbie in microcontroller. Where is the best site to study it?

 

[barny451]

You could easily use the NVRAM data and address lines as input to the keypad multiplexor (e.g. d0-d2 drive a 3-8 decoder), and use one pin on the 'LCD port' (e.g. P1.0) which is driven by a tri-state buffer only when the LCD is *not* being accessed (i.e. the LCD chip select is OFF) , it being in the nature of a single processor to only do one thing at once, i.e. read the keypad OR talk to the LCD OR talk to the NVRAM.

If your keypad is >8 buttons, you could use more pins on P1 upto the 4 bits used for talking to it.

Or, how about using I2C EEPROM instead of NVRAM so you free up P2 and P0?

HTH
Barny