increase PORTs

[gelecg]

hi,
my project is:
I want a microcontroller with 40 input and 60 output.
the inputs is connect to optocopller and the output is connect to relays.
so what is your idia about increse the port?
for example with mega32 or mega128 or other avr microcontroller.

 

[wkrug]

The easyest way to do this, is to use cascaded shift Registers with latch like the 74HC595.
They can be cascaded an need only a few connections to the controller ( RESET, DATA, CLOCK, OE, CS ).
For the Relays I'll suggest You, to use Darlington Drivers like the ULN2803 between the HC595 and the Relais.
The needed Free Wheeling Diodes are included there too.

For the Optocouplers you can use a parallel in - serial Out Shift Register. For a useful Type you had to google a little bit.

So you can built your Project with a ATMEGA 8 Controller when want.
For the input i would take the Hardware SPI of the Controller, because it works 4 to 8 times faster then an Software SPI and relais are very slow for a Microcontroller.

 

[Pommie]

A 120 pin chip.

Mike.

 

[wkrug]

...Or use a 100pin One like ATMEGA640 or 1280. The Inputs with direct Connection and the Relay Output via the Shift Register and additional Drivers.

 

[پروژه های الکترو]

hi,
my project is:
I want a microcontroller with 40 input and 60 output. پروژه الکترونیک میکروکنترلر
the inputs is connect to optocopller and the output is connect to relays.
so what is your idia about increse the port?
for example with mega32 or mega128 or other avr microcontroller.

There is various options, from using a bigger chip to implementing IO expander with shift registers or CPLDs.