a. SV PIC18F2xJ50 STARTER KIT SCHEMATIC

Here is the schematic of the starter kit:

The starter kit incorporates a starter circuit that prevent excessive electric current inrush. When the starter kit board is plugged to USB powering two microcontrollers would temporarily overload USB power supply, therefore a p-MOSFET transistor is used as a switch which is enabled by the PIC programmer microcontroller. You can use almost any 150 mA p-MOSFET transistor (like the one on the schematic, or BSS92). What is important is that the transistor fully opens at proximately -2 V on its gate input. Low opening threshold voltage is important because PIC18F2xJ50 microcontrollers work on +3.3 V=.

PIC18F2xJ50 starter kit includes programming and testing functionality. It can also be used to build circuits that allow firmware upgrade without an external microcontroller programmer. Both PIC18F2xJ50 microcontroller firm wares can be altered in-place. This is because each microcontroller has the capability to set MCLR signal low and start ICSP sequence on the other microcontroller. One of the microcontrollers is connected to the ULN2803A relay driver and can drive up to 8 relays without the need for any other external circuitry (see section 2 for more details). The inputs of port A and port C are intended for digital and/or analog input and they are directly connected to the input connector. Please, read subsection 2.b, if you intend to connect power electronics where input protection might be needed. To protect a digital input against negative impulses and inducted voltage it might not be a bad idea to use an additional ULN2803A IC to protect digital inputs as well as operation amplifiers to protect analog inputs and to adapt the voltage ranges, especially if you would like to use A/D conversion in AC signals.

Both PIC18F2xJ50 microcontrollers have equal programming capabilities, but one lacks ULN2803A relay driver. If you need more outputs you can also connect a ULN2803A IC both microcontrollers as well as additional ULN2803As and operational amplifiers to enable digital and analog inputs protection.

Click on the schematic to enlarge it.