USB BREAKOUT BOARD

[smarbaga]

Hello All.
While awaiting parts for my PIC servo controller (mtmc),
I have layed out a usb bob.
No programming has been done for this yet, but i don't think it will be very difficult as it is basic input/output.
There will be a boot loader in the chip as to upgrade or change the software
via the usb port.
I don't know what kind of data some of the cnc software puts out over the usb.
Because the bob has a cpu it can easily modify the in and out data to match
a particular software package.
If anybody has some information on the data that a particular software put out to the usb this would be very helpfull.
If others are interested in this project i will persue if further ( ie: pcb's made etc).
Otherwise i will just solder breadboard this and use it as a general purpose usb i/o.

[smarbaga]

I was looking at mini itx mother boards the other day and not to many of them have parallel printer ports.

[Percy_Mistry]

Hi. Looks very promising and I'd like to see how it unfolds. I could be wrong about this since I've never worked with the 74ACT245 IC but The only criticism I have is that there is no isolation circuitry built into the board. Without this isolation, you are taking the chance of potentially damaging the breakout board or worse; damaging the computer itself. That's my two cents worth for now.

Take care and good luck. cheers! :-)

[smarbaga]

I had forgot about in/out isolation.
Most of the stuff I do is chip to chip.
These i/o bus drivers always gave me a solid signal.
Below is a rough drawing of the previous usbob only isolated.
Now i am not sure which one i will use.

PS: I see a lot of software that redirects things to the usb.
Has anyone used any of this software and with what sucess?
Thanks for looking.
reguards Garry

[dewayne]

Nice work, do you have the files in eagle format if so can we have them pls

[nnpepe]

In answer to your code question from CNC software most of the stuff that I've seen uses ASCII code, you need to know the protocol (data packaging) for the particular machine -- Start bits, Stop Bits, Data bits, Partity (None, odd, even), Baud rate and stuff like that. Then you need to know what the machine expects things like CR (Carriage Return) LF (Line Feed, the non-printable ASCII -- control code). Working with the PIC unit you are probably using a programming language like "C" or even a little closer to machine code like "Assembler".

The '245 is an Octal Bus Transceiver (communicates in two directions, depending on state of direction control and enable logic)) with 3-state output -- Hi, Lo, or High Impedance (Resistance).

Hope this helps.

[nnpepe]

If you get a Serial/USB converter it works quite well. You can get the cable and software at any electronics supply house (Radio Shack). I use them for a multitude of applications. I marry PC's to machines, electronic gauges, Machine Vision, Motion Controls, PLC's and a myriad of sensors and other devices.

Hope this helps.

[smarbaga]

My intention is to have the pic chip hold a usb boot loader, this way the code can be changed on the fly to match any particular software package.
I don't use eagle but i have the gerber and drill files if anyone would like them I can post them.
I will put together a soldered breadboard of this unit, i have a bunch of
74245's so i guess i will use them and if necessary hang some isolators off of the ends of them.
garry

[smarbaga]

tried to add this file to my last post, but i guess it didn't go.
attached file fixed pcb/

[smarbaga]

Attached are the thumbs of the schematic and proposed pcb.
This board could be used as a general purpose controller as well.
reporting inputs back to the PC and/or acting on them via the pic cpu.