Digital DC Power Supply Unit
============================

Compile the software and program the microcontroller:

1) edit and adapt the file hardware_settings.h 
   (calibration and selection of the right hardware type).

2) load and compile:
make 
make load

3) set the fuse bytes to 4MHz internal:
make wrfuse4mhz


The make wrfuse4mhz needs to be done only once
unless you change the Atmega8 chip. make/make load
need to be repeated everytime you change something
in the software (e.g update of hardware_settings.h). 

The poweresupply must be powered up during programming
but nothing should be connected to the output. Make
also sure that you do not accidently press any button
during the programming (loading the software into the uC).

Calibration
===========
To calibrate the display edit the file hardware_settings.h
Here you can change also the settings between the 30V and the 22V version.

Note to windows (WINAVR) users (linux users ignore this):
========================================================
To compile only the .hex file for the microcontroller
run make the command:

make main.hex

After that the microcontroller has to be programmed (download
the file main.hex to the microcontroller) and the clock frequency 
has to be set to 4MHz. That is: change to lower fuse byte to 0xE3 to
get a clock frequency of 4MHz.
How this is done depends on the programmer that you use.

Under other_os/win are source code and ready made 
win32 binaries for the remote control feature of this 
power supply.

---------------------------------------------------------------

Overview
========
This is the software for the tuxgraphics.org electronic digital DC power supply. 
A microncontroller controlled bench DC power supply unit. 

All of the control logic is implemented in software. This
saves a lot of parts compared to conventional lab-power 
supplies. This means it is cheaper, easier to build and
offers more functionallity.

Note however that this means also that the short circuit
protection is implemented in software. So be careful when
you change something in the software. If the microcontroller 
is not running properly due to a software fault then there
might not be any short circuit protection.


The software is prepared for 2 versions:
- 0-22V 0-2.5A
- 0-30V 0-2A

It is possible to build a different version without major
re-design. 

The hardware has as of this release features which are not
yet supported by the software:
- store settings to survive a power off
- i2c driver interface to linux PC

---------------------------------------------------------------
How the software works
======================

I have added a lot more comments to the software than usual. 
It should be possible even for somebody with little experience in
C programming to understand how this software works.

The circuit uses as internal units ADC steps. All external values
(Volt, Ampere) are converted to steps of the analog to digital 
converter (ADC). When you change the voltage then this is first
converted to ADC steps and then it will be further processed.


main.c -- this is the main program. All initialization starts here.
 It contains a infinite while loop which will execute the slow tasks
 one by one: 
   + Convert ADC results to display values
   + Update the LCD
   + Check push buttons
 
analog.c -- the analog to digital converter and the main control loop
         for the power supply. Everything is interrupt based here as
         it needs to be fast.
         Voltage control, current limitation and short circuit protection
         are all implemented here.

dac.c -- the digital to analog converter. Initalized from main.c but
         used exclusivly from analog.c

kbd.c -- the keyboard driver

lcd.c -- the LCD driver. This is a special version which will not need
         the rw pin of the display. It uses instead an internal timer
         which should be long enough for the display to finish its task.
         The RW pin which is normally used to poll the display to see
         if it is ready is not needed.

-------------------------------------------------------------------
Copyright: GPL V2
Author: Guido Socher
Homepage: http://www.tuxgraphics.org/electronics/
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Change history:

digitaldcpower-0.5.1 -- 2007-09-25 Corrected typo in readme.htm file.

digitaldcpower-0.5.0 -- 2007-07-10 first public version for the second generation
                        of the tuxgraphics Digital DC Power Supply.
			Based on digitaldcpower-0.4.10

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