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10-23-2010

USB Small Peripheral Board (aka PIC18F14K50 Board)

Recently I’ve working with the little but smart PIC18F14K50 (or your low voltage version, PIC18LF14K50). These chips are cheap (about $2,5 at Mouser) and have low pin count, but very impressive specs:

  • USB V2.0 (low and high speed);
  • NanoWatt feature (sleep with 24nA!);
  • 10-bit A/D converters with auto-acquisition;
  • PWM;
  • Several Internal Clock modes;
  • EUSART;
  • 16KB Program Flash Memory;
  • 768B SRAM;

They help me with USB development. The low pin count don’t became a problem because most of times, my projects don’t use all them.

I think that it’s a good choice to design some little USB devices, like:

  • A USB accelerometer;
  • A USB thermometer;
  • A USB logger;
  • A USB GPS;

The possibilities are awesome!

Microchip develops a kit, called “Low Pin Count USB Development Kit” to present this chip. But the Microchip kit have dimensions, don’t very suitable to work like a real USB peripheral.

USB Small Peripheral Board (aka PIC18F14K50 Board) Finished

So I design a little board, with minimum parts to make it work. The board is a first prototype, a experiment. If works, I’ll improve it with more polish design and features, and design one with PIC18LF14K50 for 3.3v native support and etc.

You can see the circuit and board below:

USB Small Peripheral Board (aka PIC18F14K50 Board)
Click to enlarge

USB Small Peripheral Board (aka PIC18F14K50 Board)

 Well, my board comes to me and I’ve soldered all parts. The board is really small, very compact, very robust. I’ve made a little test only to check if are something wrong, but not. Everthing works well. Very good for version 0.

See the photos:

USB LowPin Kit on Breadboard

USB Small Peripheral Board (aka PIC18F14K50 Board) Programming via PICkit3

Now, I (and you, please contact me if you like it) can test and make nice devices, without boring with crystals, capacitors, reset, USB it self. You can attach it on a breadboard or your own prototype PCB with your circuit.

I’ve created a kind of pin card, for rapid pinnout reference. I got the card idea from Mbed project. It’s very useful, with all pins and ports plus the information about device peripherals.

USBLowPin_pinnout

PIC18F14K50 USBLowPin_pinnout
Click to enlarge

Think the nice things you can do… I want to make a test with USB Mass Storage Device, yes, a Flash Drive. I’ve a little project where this really help me with configuration storage, etc.

For test, I’ll show us some application example, like a USB RFID reader.

Downloads:

Low Pin Count USB Development Kit User’s Guide (Microchip)
Development Kit Project Labs (Microchip)

rusticengineering.wordpress.com

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