Step 2Construct PCB
If Purchasing A PCB or Making one yourself, have it ready before beginning this step. Perforated board could also be used, then just follow the schematic.
The silkscreen PCB layout image included in the ZIP in Step 1 should be accessible for this Step, it shows the parts layout.
- Start with the 20-pin socket, the notch on the end marks the Pin 1 end. Carefully insert it, ensuring all pins line up.
- Resistor Buses are next, they each have 5 10k resistors in parallel within them with a common pin on one end, The common pin, which is marked with a dot on the SIP package should be lined up with the printed dot on the end of RN1 and RN2.
- Oscillator, ensure the solder joints are shiny and designing your own board, it should be as close to the MCU as possible.
- Capacitors C1 & C2: C1 is a 100nF disc cap for decoupling, C2 is a 220nF capacitor connected between the MCU's VBUS pin and V+.
- Resistor R1 pulls the Data+ line high, which signals to the Host what USB speed the Device runs at.
- USB Receptacle: It only goes in one way, Bend the mounting pins outward once it is in the board, solder all the contacts ensure their good joints. Make sure the solder doesn't bridge, as the contacts are quite close together.
- Headers: The polarized headers go in now, they can go in facing either way, there is a 4-pin and a 6-pin.
- PWR: Unused power header, leave it empty but solder over both pads. It is there in case more power than the bus can provide would be needed if the device was repurposed.
- Jumpers: Lastly the jumpers are installed, using these means that single sided copper circuit board can be used. Use some solid strand wire. And avoid other touching other parts, especially bare wire line on a capacitor.
- J1 is jumped to J2
- P1 is jumped to P2 which is jumped to P3. solder 2 wires into P2, then one wire each goes to P1 and P3.
- G1 and G2 are left open, explained in the next step.
- RX and TX are also left open and are not used, but are connected to the USART.
All the electronic parts except the PIC microcontroller and switches should be installed onto the circuit board. Look over everything carefully for jumps, bad solder joints, loose wires, or parts.
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