ND2E

Finally got back to working on the solar hot water home heating controller. I am using the Pic-EL as my test bed to work out the final solution to my friend's solar controller. Many months ago I finished assembling the Pic-El 3 and started learning MPASM the assembler for the PIC controllers. It has only been 30 years since I played in assembly language and then it was IBM Basic Assembler not any of the more recent microprocessors like the 6501 0r 6800. I missed that entire generation. So my first outing was to copy the LED flasher program from Peatman's "Design with PIC Microcontrollers." I got everything typed in and started looking for why I was seeing several assembler messages, warnings, and why it failed to assemble. After several hours of inspection spread over several months I finally have it assembled, and downloaded the code to the PIC-EL. The new task is to understand what is going on and how to use the banks and I/O pins for the controller. I have done a state diagram for what I think I want and will try coding it as soon as I better understand the PIC I/O, timer, and comparator structures. This probably means writing several short programs to exercise the PIC to learn how the I/O is works to drive LEDs and relays, how the timer can interface with the mainline to start a sample at one or more of the comparators and how to do controlled restarts. I don't yet now whether it would be better to sample the temperature of the water in the solar heat plant or to go directly and look at the solar radiation input. From what I am seeing with my solar battery charger, the solar side may not be sufficiently accurate to do what my friend wants. I need to write a bit of code for the PIC so I can have a recording voltmeter on the solar charger. That should give me some idea of what to expect if I use solar radiation as the input to the controller. In any case progress is slow and unsure. Hopefully I will be able to publish the code and schematic when I finish the design and have it installed and it actually works.