Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

ATMEGA32L & PPI (8255) interface question

Status
Not open for further replies.

NTFS

Member level 3
Joined
Apr 6, 2004
Messages
67
Helped
1
Reputation
2
Reaction score
0
Trophy points
1,286
Activity points
576
ppi 8255

Hi

In a project I should to handle many I/Os (GLCD, K/B, many lamps, buzzer, 2 fans, 4 sensors, heater and a DC motor ). So I used two PPI (8255) and micro ports.

Now how can I handle PPI control signals? (A0, A1, RD, WR, CS)

I thing, I should do that manually by micro ports, because I couldn't find a method that when I write to PPI, micro does [WR, A0, A1, CS] signals automatically.

So two questions:

1) what is the best method to interface these many I/Os to micro? Is my method good?

2) How to handle control signals? if I active these signals at a same time, does PPI
work? or I have to do them in separate times? for example first I should active
CS, A0, A1 then put data on port (data bus) and then active WR (write) signal



Thanks in advance.
 

IanP

Advanced Member level 5
Joined
Oct 5, 2004
Messages
7,942
Helped
2,311
Reputation
4,624
Reaction score
531
Trophy points
1,393
Location
West Coast
Activity points
66,416
i2c 8255

This ATmega microcontroller had not been designed to co-operate with older PIOs such as the 8255, so maybe you can consider the already built-in two-wire interface, namely the I2C, and expand the number of IOs by adding some PCF8574-s or any other I2C-compatible expanders ..
https://www.i2cchip.com/pcf8574.html
Using 8255s is still an open option, but it can be a little bit tricky, especially if you are not familiar with the multiplexed A/D parallel bus ..

Rgds,
IanP
:D
 

    NTFS

    Points: 2
    Helpful Answer Positive Rating

nandhu015

Advanced Member level 5
Joined
Feb 11, 2006
Messages
1,965
Helped
300
Reputation
600
Reaction score
224
Trophy points
1,353
Location
India
Activity points
9,861
interfacing ppi to atmega32

Another Simple way is to use a serial in parallel out shift registers

There are a lot of examples of lcd using these chips, google and find one

Nandhu
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top