Hi,
This is officially my first Thread and its a big one! I hope I have selected the right forum section...
I have been browsing the forum posts reading and learning a lot for a past 4 or so months and You guys rock.... Its about time I gave something back I am in the process of developing an Open Source/Freeware Budget USB DAC for everyone that is keen....
Now I have been throwing a few specs around (inside my head and with carmangary) and would like some more input before I start laying out the schematic and building a proto-pcb.
This USB DAC will be based on the PIC18F4550 the reason being is that I have worked with this device for about a year now at work and it is rock solid. The API and sample embedded applications are provided free of charge by MicroChip this is to speed up development.
I have mainly been involved with developing DMX512 lighting for my mobile disco which is my main hobby (since 1988). I have developed a few DMX512 items that I have been using for the last 8 years:
1) 4 channel DMX512 dimmer/switch pack
2) 8 channel DMX512 dimmer/switch pack
3) Wireless DMX512 link using Zigbee (300m line of sight NO DROPPED packets)
4) RGB LED lighting effects (still currently in development)
My MOTTO in life is: " If I cannot build it, I will have to buy it "
Now I am crazy when it comes to entertainment lighting and even more crazy when it comes to LASER's - I have 2 pre-built JB Systems LASER's (TwinScan, dual green beam, and a single beam RGY Space Color) they get the job done but alas no proper control, they both have preset built in patterns......
So when I found Photolexicon I went bananas and I can't wait for my annual bonus in December as I am going internet shopping in a big way... I WANT a proper LASER...
This is were this USB DAC comes in I want to build my own, I know there are interfaces out there that could do what I want but I am looking forward to sleepless nights of bug fixing.... its FUN.
Now for some USB DAC SPECS:
1) On Board RAM
64K base RAM with upgradeable modules to increase memory to 1MB - user budget dependant.
2) uP
18F4550 Full USB 2.0 12Mbits/sec transfer rate.
3) DAC chipset
12 bit MCP4822 for X,Y,R,G and B - there will be one free output as these chipsets are dual DAC's in 1 package, possible 16 bit once I source a decent chipset... any suggestions..??
4) Output swing
+/- 10V ???
5) TTL outputs
8 TTL open collector outputs, upgradeable depending on user's budget.
I2C bus.
6) SD Card facility
To store shows/effects so DAC can be used in stand alone mode.
7) Modes
4 Dip switches to select modes and configurations.
1 Dip switch will select either analog or TTL modulation depending on the type of Laser used in projector.
8) DMX512
1 X DMX512 Universe input and/or output.
9) Built in BootLoader
This is a facility for users to update the PIC18F4550 firmware without the need of a dedicated MicroChip programmer.
MicroChip do not ship these uP's with the Bootloader preloaded so I will have to work around this issue, I might be able to supply pre-Bootloaded PIC18F4550 if a user does not have the facility to dump the Bootloader into a new uP themselves. I use an ICD2 to dump the Bootloader there after I use the Bootloader facility.
10) User Manufacture
All chipsets and components will be leaded components so as to make construction easy.
I will be able to supply a nice neat PCB layout for this USB DAC once it is finished, the prototype will be developed on what we in South Africa call VeroBoard it's a prototyping PCB and it is very cheap.
11) A Name
It will need a decent name.... any suggestions...??
Well if there are any of you guys that can add some ideas/specs feel free to add... I will start the schematic layout on the weekend.
Cheers
Paul