Insufficient I/O ports in MCU

ErnieM

Joined Apr 24, 2011
8,377
Ugh... if that is the future then there is no future.

Instead of long fly wires header pins make a short neat connection. You can use a header receptacle too if you want to make a socket:



It can give your project much better layout.

Down in the attachments is my current project (sorry I can't get clear close ups with my camera). There's a PIC18F47J53 in a 44 lead quad flat pack package as the controller, SOIC for an 18 bit A2D and a RTC, socket for a micro SD card, USB bus, LDC display, 5 button keypad (on a custom PCB, I use that scheme a lot) plus a few other things.
 

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takao21203

Joined Apr 28, 2012
3,702
I had these. Way too much effort. I use flywires now directly through the PCB hole and into the SMD adapters.

Parts from epoxy boards are very hard to remove as well- considering most prototypes don't actually work or are not needed anymore after a while.

So, taking care of that in advance can't be wrong.
 

ErnieM

Joined Apr 24, 2011
8,377
If most of your prototypes don't work perhaps you should investigate better construction methods.

My prototypes get packed away and stored in case months/years later I need to go back and make some measurement.
 

Thread Starter

raychar

Joined Nov 8, 2011
82
Hello,

For last couples of years, I also stored dozens of prototype boards in which some were assembled neatly and its' codes were filed properly. I did go back to review them some years later. Somehow, however, i still need take much time to digest how the schematic, codes and hardware function before i can fully understand and operate them again...especially for complicate project... sometimes some solderings or wires broke and need reassembling or debugging?!..

As they consumed much hardwares; electronic parts (though main mcu usually unplugged for reuse), assembling time. I am now awared the benefit of standard development/demonstration board it provides for us and now want to purchase one.

Thanks,
 

takao21203

Joined Apr 28, 2012
3,702
If most of your prototypes don't work perhaps you should investigate better construction methods.

My prototypes get packed away and stored in case months/years later I need to go back and make some measurement.
Not as I wanted or useless for any further use.

Some of them are complicate circuits, which work, but can be built in a much better way. They only served some limited purpose.
 
Hello, everybody,

I have many I/Os lines in my circuit and the current PIC16F877A can't fullfill the requirement. Currently, except the MCLR, OSC1, OSC2, PGD, PGC, PGM pins, all others are used. I also use multplexing method and input and output lines on the same port method. As I don't want to make the circuit and program so complicated and also now, still is of shortage five I/Os. Are there other MCU models which have more I/O pins that I can used instead of this one or some other methods?

Thanks,
If it's digital ports you need and have already written your code or are stuck with a specific mcu, you could use an I2c port expander.
They come in 8,16 and 40 port variations - and they need a couple of pins on your MCU either the "real" I2c ports, or if you dont have an i2c peripheral on-chip, you can use any 2 pins and bit-bang your own.
http://www.ti.com/product/pcf8575
I've never used one of these, as I usually over-engineer things (64-pin TQFP packaged PIC18F67K22 on the current design)
 
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