interfacing lcd + keypad with cpld

[bittuk]

i read th post by zelec , related to interfacing the lcd driver + key pad using cpld . but i want further guidance on this .
i want to interface the lcd + keypad with cpld from xilinx and i want to do the coding in vhdl language .
if anyone could help me with this , it would be of such a great help . please please let me know!!:| .
thank u !

 

[m_ali]

why do the whole interfacing part in CPLD?
Interfacing LCD with CPLD only would be a bit tedious because it would require you to meet the timings of read/write cycles manually. Whereas when you do it using uC you can program your bus to certain wait states between reads and writes which basically takes care of the timing. But you can still program it. Making a read module , a write module. which can take command as parameters since it would require multiple commands for initialization part.

if you manage to take care of the above mentioned issues , namely:
-timing
-read module
-write module
and are able to synthesize it all in your CPLD resources. you are good to go.

For the keypad, i am assuming you are not using any sort of keypad encoder and are relying on plain old rows and columns. if that is the case, depending on the matrix of your keypad (e-g 4x4) you'd need that many spare pins on the CPLD. Other than that, there is no issue in keypad interface.