Update on PIC-USB boards

[Carl-NC]

I have received USB boards and have been working on getting one running. Something has gone terribly wrong... my bootloader code has quit working, and I have yet to figure it out. So I went back to the original Microchip code, and I cannot get it to work, either. Furthermore, in testing code on my Microchip demo board I've gotten that chip in a state where it doesn't work. Sheesh!

I am about to leave on extended holiday travels so I'm afraid the PIC-USB project will have to wait until I return in January. Stay tuned...

- Carl

[Berti]

hi

Have a good holiday!

New year, new ideas, new thoughts .....


Marry Christmas and Happy New Year


cheers
B

[Carl-NC]

Update on the USB-PIC boards...

I'm not exactly sure why it quit working, but I have finally gotten the bootloader going again. I am back to finishing up the IO functions. I can change the read/write direction of pins and can write bit values to pins. I need to code a read-pin function to complete the basic functionality.

The PCB seems to be 100% good to go. I'm trying to decide whether to sell blank PCBs or to provide a semi-built board that is pre-programmed. Or maybe both. I'm thinking of $8 shipped (USA) for the bare board, and $35 shipped (USA) for a built/programmed board. $5 extra for overseas.

The built/programmed board would consist of the PIC, USB jack, oscillator, R's & C's, push buttons, and jumper posts. It would not include the 3.3v regulator or the power jacks, so it would initially be limited to running off the USB power. But it could easily be upgraded for the other power options.

If I decide to sell built boards I will have to limit it to one a person, and will probably limit it to established Geotech members. I would like to see how much interest there is, so please reply to this thread as to whether you might want a blank board or a built one.

As a reminder, this design is a PIC4550 with a complete USB interface, so you can program it via USB (no PIC programmer required). You can also communicate with it from a PC while it is running, so you can alter the program on-the-fly (PI timings, ferinstance), or change output bits, or read bit settings (or ADC), or log data, or whatever you want. PC-Windows software is easy.

- Carl

P.S. -- there is a new PIC4553 that is identical to the 4550 but has a 12b ADC instead of 10b. However, it is 50ksps instead of 100ksps.

[Qiaozhi]

Hi Carl,

Could you also offer a kit-of-parts? i.e. the blank board + components.
If so, how much?

[KingJL]

I would like to see how much interest there is, so please reply to this thread as to whether you might want a blank board or a built one.

Built one here, please!
Regards,
J. L. King

[Tinkerer]

USB board

I would like a built one please.

Tinkerer

[Qiaozhi]

Hi Carl,

Could you also offer a kit-of-parts? i.e. the blank board + components.
If so, how much?

If no-one is interested in a kit-of-parts, then I'll go for a built one.

[bbsailor]

Carl,

I would be interested in a circuit board and a kit.

bbsailor

[Carl-NC]

I can do a kit, for maybe $20 which is pretty close to my cost. However, the PIC won't be programmed with the bootloader... this is done after it's soldered down. But if you have a regular PIC programmer this will be easy to do, and you only do it once. After that all programming is via USB.

So here's where I'm at:

$8 -- Bare PCB only
$20 -- PCB & components
$35 -- Assembled & programmed

I got a basic read-pin function working, but there are a few quirks I need to figure out. Hopefully by the end of next week, I'll have everything ready to go.

- Carl

[Tim Williams]

Carl what is this project about? A USB programmable project board with boot loader?

Tim

[KingJL]

But if you have a regular PIC programmer this will be easy to do, and you only do it once. After that all programming is via USB.

Carl, I'm confused. Almost all of the in-circuit programmers use the JTAG connection to program the uPC (even the USB ones like PICKIT II). The USB shouldn't work until there is bootloader code. Although a JTAG could be kludged using the uPC header pins.
Am I mistaken? It wouldn't be a first!
Regards,
J. L. King

[Tim Williams]

On my controllers the boot loader has to be programmed in the chip from a programmer before USB can be used to program the chip. Things change fast so it may be possible with the chip Carl is using.

Tim

[Tim Williams]

Carl I use the FT232R - USB UART IC from
http://www.ftdichip.com/FTProducts.htm#FT232R

It works great and save code space. Plus you can use any chip.

Tim

[Aziz]

Hi friends,

my USB AVR programmer uses the CP2102 chip. It is an USB to UART bridge chip and quite easy to use. The USB driver installs a virtual RS232 port to access the UART interface. Any micro can be interfaced to the UART interface. Writing an applification specific USB driver software isn't trivial for amateurs. So the RS232 and UART API is easier to use and saves a lot of work and as Tim mentioned a lot of code space.

For high-speed and high bandwidth applications of course, an USB interface is a must have demand. Anyway, Carl is supporting to break the barrier of old interfaces. This could bring some interesting new applications.

I would be interested in how to realize knowledge.

Aziz

[Carl-NC]

Tim,

Please read the other thread in this forum, "The Basics of USB-PIC". It has a schematic.

The purpose of this project is to create a small (2"x2") independent circuit board that can be patched in to any design. It is basically a single chip 18F4550 micro that has a built-in USB interface, so no other chip is necessary. Here are some highlights:

• The USB-PIC board can be powered off the USB cable, up to the USB limit of 500mA.
• For higher currents, USB-PIC can be changed to an external supply.
• USB-PIC has 30 available I/O pins that can be patched into any circuit.
• The 18F4550 can run up to 48MHz.
• Once a permanent bootloader is installed, PIC firmware can be directly programmed from the USB, no special programmer required.
• PIC firmware can use the USB while it is running. You can write software for the PC that toggles a port when you click on a checkbox, or you can change firmware parameters on-the-fly. For example, if you use the PIC to create all the pulses for a PI detector, you could have PC software with a bunch of timing controls and, while the PI is running, change any of the timing parameters via USB. In short, the PC can become a programmable control panel for your detector during development.
• You can also use the USB to read information from the PIC while it is running. You could read the value of a port, or log data from the PIC's ADC.

Yes, you do have to program the bootloader using the standard PIC ICSP interface, basically 3 pins. Then it's all USB.

- Carl