In addition to the power supply that you created on your breadboard in Lab 2, you will need the following equipment/components to complete your PIC prototype board:
In this lab, you will build a prototype PIC system on your breadboard and test it. You'll begin by modifying the 3.3V power supply that you built on your breadboard in Lab 2.
The circuit that you built in lab 2 is depicted below. Make sure that you note any deviations between the schematic below and your breadboard. For example, several of you may have "lost" your fuse and have replaced it with a wire. It's important replace the fuse, and any missing components, in the final PIC system created today. Also make sure that your resistor and capacitors match the specifications stated below.
Once your starting configuration matches that show above, it's time to modify it.
Locate the power connector and wall transformer shown below.
Plug the power connector into the wall transformer and use your multimeter to determine which two pins on the power connector provide +6 V and ground as shown below. Each power connector has three leads, but only two are used.
SOLDER wires to the power connector, and connect this to the power/ground posts on the breadboard as shown below. The ground post is connected to the ground rail, but the +6 V power post connects to the input power switch which will be installed next.
Use the multimeter to verify that you are receiving 6 Volts of power at the connections to the breadboard before proceeding.
The input power switch allows you to isolate your system from the wall transformer without disconnecting wires. Our switch is a single-pole double-throw slide switch, which in simple English means that the center pin (the pole) is always connected to one of the two outer pins, and that connection is determined by the position of the slide on the top of the switch.
Connect the input power (from the power connector) to one of the outer pins of the switch, and the fuse to the pole. Verify your connection by properly positioning the switch and seeing that your power light illunimates.
As our final modification to the power supply, we'll connect a 6-pin header to the board and wire it to the power switch and to ground as shown below. The figure below represents our complete board layout up to this point.
Verify that your power light is still on after connecting the header pins and then disconnect the wall transformer. You should have power disconnected when you work with the PIC processor.
|Show your breadboard power supply to your instructor.|
The PIC24HJ32GP202 processor is shown below. Note that each pin has a function and that the pins are numbered starting from the top of the chip which is marked with a semi-circular notch. More information about the PIC processor can be found in the product datasheet.
Our next objective is to place the PIC processor on our breadboard and create the connections described pictorially below. Follow the itemized steps below to create this configuration on your breadboard.
|Show your board to your instructor.|
Now we will create the connections that enable the PIC processor to communicate. The figure below shows the USB-to-serial cable and the connecting 6-pin header. You placed the header pin on the breadboard in Part 1 of this lab.
There are only three connections between the PIC processor and the 6-pin header: MCLR (pin 1), TX at RP11 (pin 22), and RX at RP10 (pin 21), as shown below.
Your completed breadboard should look similar to that shown below. In the image below, the USB-to-serial cable has been connected to the header pin.
|Show your board to your instructor.|
The PIC processor that you've placed on your breadboard has already been programmed to blink the LED connected to pin RB15. Verify that your breadboard configuration is correct by connecting your USB-to-serial cable to the 6-pin header as shown above. In this configuration, power is supplied through the USB-to-serial cable and it is not necessary to connect your board to power via the wall socket transformer. To use the power supplied by the USB-to-serial cable, reposition the power switch to connect to the power wire from the 6-pin header. If the LED connected to RB15 is blinking when you connect the USB-to-serial cable to your desktop computer, your job for today is done! If it is not blinking, compare your breadboard wiring to that shown in the final figure and try to correct any errors that you find.
|Show your final breadboard configuration with a blinking LED to your instructor.|