Summary of Basic circuit for PIC18F24J50 or PIC18F26J50 to work over USB
This article details a basic USB circuit compatible with PIC18F24J50 and PIC18F26J50 microcontrollers, requiring specific firmware uploads. It explains how to configure the system for standard programming or super-speed operation using K8055 adapters. The text provides guidance on selecting crystal resonators (4–20 MHz), capacitor values, and necessary software tools like PIC Programmer v2.6+ and HEX Editor v3.0.
Parts used in the Basic Circuit:
- PIC18F24J50 microcontroller
- PIC18F26J50 microcontroller
- PC USB Projects HEX Editor v3.0
- K8055 adapter
- K8055N programmer
- DIP socket
- Resistors
- Transistors
- Capacitors
- Crystal resonator
The basic circuit below will work with any PIC18F2xJ50 microcontroller. You just have to upload the appropriate firmware. Go to Downloads section to find firmware hex files for the microcontroller and the resonator you would like to use. PIC18F24J50 firmware v2.6.3 – all subversions.zip contain the following general use subversions: 4 MHz, 8 MHz, 12 MHz, 16 MHz and 20 MHz, and the following subversions for K8055 adapter: 4 MHz, 8 MHz, 12 MHz, 16 MHz and 20 MHz. PIC18F26J50 firmware v2.7.8 – universal.zip or later enables a wider range of settings. The package contains PC USB Projects HEX Editor v3.0 which makes it possible to set new EEPROM defaults before programming a HEX file.
Yes, the basic circuit may also serve as a super speed microcontroller programmer (you must manually select option 02 – Super speed K8055 or K8055N programmer in PIC Programmer aplication, or set VID = 10CF (hex)). You just need to use a small piece of PCB to solder a DIP socket and a few resistors and two transistors and two capacitors. Don’t mind about the circuit in the plastic box. It is K8055, but you don’t need it! Use PIC Programmer v2.6 and above for PIC18F2xJ50 microcontroller with v2.2 firmware or later, and previous versions of the application for PIC18F2xJ50 microcontrollers with any versions of the firmware
If you would like to use the basic circuit for PIC18F2xJ50 microcontroller programming, just go to subsection 4.b and build the adapter initially intended only for K8055 and K8055N boards. The adapter also works perfectly, if you stick it between the basic circuit DIP socket and the PIC18F2xJ50 microcontroller that you are going to use as a programmer for another PIC2xJ50 microcontroller. You may also use the originally programmed Velleman PIC18F24J50 microcontroller with the basic circuit, if you build it with 4 MHz crystal resonator and appropriate capacitors. See subsection 5.c. to get details on choosing the right capacitor values.
For more detail: Basic circuit for PIC18F24J50 or PIC18F26J50 to work over USB
- Which microcontrollers are compatible with this basic circuit?
The circuit works with any PIC18F2xJ50 microcontroller. - How can I enable super speed programming mode?
Select option 02 - Super speed K8055 or K8055N programmer in the application or set VID = 10CF hex. - What software is required to program these microcontrollers?
You need PIC Programmer v2.6 and above for v2.2 firmware or later. - Can I use the original Velleman microcontroller with this setup?
Yes, if you build the circuit with a 4 MHz crystal resonator and appropriate capacitors. - Where can I find the firmware files for different frequencies?
Firmware hex files are available in the Downloads section for 4, 8, 12, 16, and 20 MHz. - What components are needed to create a small PCB for soldering?
You need a DIP socket, a few resistors, two transistors, and two capacitors. - Does the K8055 plastic box circuit need to be built?
No, you do not need it as the basic circuit serves the purpose. - How do I change EEPROM defaults before programming?
Use the PC USB Projects HEX Editor v3.0 included in the package.
