The LED2 along with current limiting resistor R11 indicates that Vdd is switched to output. The LED1 with current limiting resistor R12 indicates that the circuit is powered form USB. The diode D2 protects the circuit from external Vdd. The MOSFET Q2 with resistors R1, R17 provides active pull down to Vdd output whenever required. The Vdd sensing feedback is given to the analog pin AN1 of the PIC via resistor R6. The MOSFET Q3 and resistor R16 are for switching Vdd to output whenever required. The MOSFET Q6 and resistor R4 ground the MCLR output whenever required. MOSFET’s Q4, Q5 and resistor R5 are used for switching Vpp to MCLR/Vpp output. The resistors R2 and R3 forms a voltage sensing feedback network, which is given to the analog pin AN0 of the PIC. The inductor L1, MOSFET Q1, diode D1, capacitors C1 and C4 forms a DC-DC converter (Buck Converter) which converts 5V from PC to 12V, which to be applied to MCLR/VPP pin of a microcontroller at the time of programming. The built-in-clock generator of pic uses external crystal oscillator X1, C2 and C3 to ensure the correct system clock rate. The USB Data+ and Data- from PC are connected to the D+ and D- pins of the PIC182550. USB microcontroller PIC18F2550 is the soul of the PICKit2. PICKit2 is a USB powered device, that is it gets power from PC USB +5V power supply.
USB PIC Programmer PICKit2 Modified Circuit Diagram The mini USB connector is replaced by commonly available USB-B connector. Bipolar transistors used in Original PICKit2 are replaced by MOSFETs, thus minimal additional components are required.ĥ. The Programmer-to-go function is not an important feature for a electronics hobbyist.Ĥ. Two 24C512 EEPROM’s used only for programmer-to-go function in the Original PICKit2 were omitted. It supports only 5V PIC’s, thus 3.3V devices a small additional circuit to convert 5V to 3.3V.ģ. So what are you waiting for? Start burning PIC microcontroller.2.
Boot loader is used to upgrade your firmware and programmer mode is to burn the PIC microchip. The jumper connection decides the mode of the programmer, i.e.First a firmware should be burnt to PIC 18F2550 using any PIC programmer and then connect the jumper as in the circuit diagram. Download firmware here.PIC 18F2550 has an inbuilt USB port which makes PC interfacing much easier.Step by Step Procedure | How to Build Your Own USB PIC Programmer Components For This Custom USB PIC Programmer
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