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Topic: FreePCB build - QFP surface mount protoboard - 0.80mm + 0.50 (Read 2680 times) previous topic - next topic

FreePCB build - QFP surface mount protoboard - 0.80mm + 0.50

Am running learn to SMD solder workshops at our local hackspace.  SMD October uses the qfp surface mount protoboard to build a basic leonardo using the adafruit 32u4 schematic.

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Schematic is from adafruit at https://raw.github.com/adafruit/Atmega3 ... 4bbsch.png

I used my free pcb build to build the master for the class.

The sketch I'm using has a button on DI2 to change the blink rate and a blue LED on DO13.

Code: [Select]
int led = 13;
int button = 2;

void setup() {               
  pinMode(led, OUTPUT);    // initialize the digital pin as an output.
  digitalWrite(button, HIGH);  // pull-up
}

void variableWait()
{
    if (!digitalRead(button))
    delay(250);                // wait for quarter of a second
  else
    delay(1000);              // wait for a second
}

// the loop routine runs over and over again forever:
void loop() {
  digitalWrite(led, HIGH);  // turn the LED on (HIGH is the voltage level)
  variableWait();
  digitalWrite(led, LOW);    // turn the LED off by making the voltage LOW
  variableWait();
}

You can buy the board from seedstudio at http://www.seeedstudio.com/depot/qfp-su ... Path=44_46

This is a nice board, I had a few suggestions if another rev of the board is every produced.

  * Add resistor pads to the USB +/- data, these are in every usb circuit I've seen
  * Add decoupling caps to the power rails, you always need these, having to use wires to connect them up make them less effective
  * Add solderable bridge or 0R resistor pads to connect usb ground to board ground
  * Add solderable bridge or 0R resistor pads to connect usb VCC to board VCC
  * Add solderable bridge or 0R resistor pads to connect xtal ground to board ground
  * Add solderable bridge or 0R resistor pads to connect ground/vcc to one end of each button
  * Add solderable bridge or 0R resistor pads to connect ground to one end of each led
  * More power/ground pins around the QFP to avoid the mass of red and black wires

This workshop is described at http://vancouver.hackspace.ca/wp/2013/0 ... ompatible/ (sold out)  Next workshop is another DP favourite, Bus Pirate v3 LTS.  I've built an LTS variant of BPv3 on a 100x50 SOB PCB.  LTS stands for learn to solder, it is all 1206 passives and leds (no resistor packs), the board is big for package spacing and uses SOIC variants of the pic and 4066.  More soon.  As per license, files will be released on github once tested.

Re: FreePCB build - QFP surface mount protoboard - 0.80mm +

Reply #1
Good suggestions for the additions / changes to the board, they would be useful. I'd suggest that you shorten up your leads though, especially on critical areas like the Crystal, etc.

FreePCB build - QFP surface mount protoboard - 0.80mm + 0.50

Reply #2
Thanks will do - its working reliably for now ;-)


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