Microcontroller - USB Data

[SamanthaL]

mchpfusb project

Hello everyone!

My group and I are working on a senior design project that is fairly complicated. It is a chip tester.

As of right now the set up is that the user will enter data to be applied to the chip to be tested in LabVIEW. From here, the data will go through a USB port to a PIC18F4550 Microcontroller which will then delegate the data to two FPGA's which will act as shift registers and switches and apply data to the DUT.

I am currently working on the microcontroller programming:

What is the easiest way to get the data into the micrcontroller through a USB? How does the microcontroller store the data? I've read the data sheet, but am still a little lost. Have any of you done a similar project? I've done work with a PIC16F487, but am new to the PIC18 and the USB interface. Any tips would be appreciated! Thanks!

 

[treitmey]

microchip usb v2.3.1 stack

If I were you I'd use the FTDI FT232RL chip.
**broken link removed**
You add the chip, a few extra parts, and your running.
((think of the ftdi chip as a max232 chip))

Example circuit FT232R spec. figure 7.4.
(i don't use cbus0/clock or CTS RTS or pwr_en)
I do use LEDs as in fig7.5

 

[btbass]

storing data onto usb from microcontroller

You can download a usb stack from Microchip for free.
Search for

'Microchip MCHPFUSB v2.3.1 Installer.zip'

This contains a lot of sample code including the pc end for usb comms.
You should be able to use some of this code in your application.

 

[Osolong]

microchip mchpfusb v2.3.1 installer.zip

If you are using CSS compiler (PCWH version) you can check this thread.



It contains the most basic example of PIC18 USB communication with Labview 7.1 or newer.

Let me know if you need more details or if the files are corrupted (since other people had problems downloading them).

Hope it helps.

 

[SamanthaL]

microcontroller usb attached

Thanks Osolong. That was a very useful thread.

I still have a few questions regarding the USB interface though.

1. How do we confirm that the USB is working in "low-voltage" mode (3.3V vs. 5V)?
2. I've got most of the code written except for the "USB Descriptors." Is there a generic list of descriptors that can be used for this microcontroller? My project is kind of a new thing and doesn't have specific descriptors like a keyboard or mouse for example.

Thanks again for your help guys!

 

[wavelet1208]

Re: microcontroller usb attached

I'd like used STM32,if you needs" a usb keyboard or mouse for example",here a example maybe can help you.and it include :JoyStickMouse ,Custom_HID,Mass_Storage,Virtual_COM_Port...
**broken link removed**