n. Exploring SK9 connector on Velleman K8055N board: Can it be used for programming the microcontroller “on the fly” by another K8055N board?

The purpose of SK9 connector is not immediately clear from the Velleman original Illustrated assembly manual, nor there is a definite answer what it was intended for on the Velleman projects forum. The designers of the board connected the following PIC18F24J50 pins to SK9 connector:

SK9 - pin 1 à MCLR

SK9 - pin 2 à +3.3 V from the onboard voltage regulator

SK9 - pin 3 à GND (ground)

SK9 - pin 4 à RB7 / PGD

SK9 - pin 5 à RB6 / PGC

A programmer who is familiar with detailed PIC18F24J50 operation would probably agree that all this signals could be used for programming the microcontroller without removing it from the board. The only thing that is missing is a programmer and a suitable programming application that have probably never been developed by Velleman. Instead, K8048 and K8076 PIC programmer kits are still on the list of available Velleman products. The enclosed Windows programming application for K8048 and K8076 kits cannot program 3.3 V microcontrollers, like PIC18FxxJxx. Not only the Windows application does not support them, there are also no 3.3 V regulators on K8048 and K8076 boards. The only way to program PIC18FxxJxx microcontrollers therefore would be through the SK9 connector on K8055N board, since only K8055N board can provide 3.3 V power supply. There is another seatback. Both Velleman PIC programmers are designed to operate on an RS232 port and cannot be used directly via an USB port.

However, there is a really simple solution to the problems above. It is sufices to build PIC18F2xJ50 basic circuit and make proper connections to the SK9 connector on K8055N-2 board. The only remaining problem is to get a suitable Windows programming application, but you can use PIC Programmer v2.9.9 (x64) application from the Downloads section.

You may also opt for using another K8055N board as a programmer instead of the basic circuit. Use the appropriate signals from the programming adapter described in subsection 4.b. You can also use MCLR, PGD and PGC signals from any other microcontroller programmers described on this website.

Here are all the necessary connections from the basic circuit to the K8055N board SK9 connector: