I know, I said I was working on something, disappear for a few months, than say I am working on something else. Well unfortunately I did it again. This time I am working on a power-supply which, I am hoping, will be used often as I am developing this to ease my development of other electronic circuits. Currently it has the ability to regulate voltage (step-down converter) using a switch-mode type system so effeciency will hopefully be extremely well (goal is > 85%). Overall I have a design goal of holding up to 1A of continious current but the design will allow for far more for future revisions. I am working around a microcontroller from Microchip, more specificially the PIC18F2550. Unfortunately I am utilizing every single pin of this device, so future advancements will require core hardware updates, but I want this to be small so the 18F2550 will do. Here is the pin utilization, though may change during prototyping:
PORTA
0 Vsense
1 Isense
2 LCD.CTRL.CS2 / ~LCD.CTRL.CS1
3 LCD.CTRL.RST
4 LCD.CTRL.R/~W
5 LCD.CTRL.D/~I
6 LCD.CTRL.E [H->L]PORTB
0 LCD.DATA.0
1 ..
2 ..
3 ..
4 ..
5 ..
6 ..
7 LCD.DATA.1PORTC
0 Button.Up
1.CCP2 Boost Converter Pwm
2.CCP1 Buck Converter Pwm
4.USB \
5.USB -’- PC Connectivity
6 Rotatory 1
7 Rotatory 2PORTE
3 Button.Down
The system will be able to handle buck and boost mode conversions, but currently boost-mode is only in sub-priority but hardware will be implemented for later firmware updates to support boost-mode. Two regulation modes are Voltage, and Current. The whole device will be controlled by a rotatory encoder and 2 push-buttons. The user will be able to read-back information with a 128×64 graphics lcd. This project will be enclosed in a basic hobbiest project box (black), with power jacks for input and output to give the final result a professional feel.
I will also be bringing in some pictures of the progress, hopefully within the next few days.
