pic24 usb problem

rwalborn · Joined: 12 Dec 2011 Posts: 8 Location: USA

I have run into a weird problem using the CCS HID example. Compiler CCS 5.031. I am using USB HID interface to update parameters in a speaker with DSP. I am using interrupts. Now normally , when I connect the USB cable to a Windows computer, Windows detects the device and enumerates it successful. It works on a windows 7 core dual laptop, and a windows 7 core duo desktop, and the same desktop running windows xp using VMware. However, on my faster I7 computer using a high speed usb hub , Windows gives me a error code 10 can not start. However, the device also has a firmware boot loader using Microchip HID boot loader code ( non-interrupt) and Windows has no problem detecting that. I have managed to get it to work most of the time by speeding up the main control loop which the software executes to check status of switches.

Does anyone ever experience anything this?

Ttelmah · Joined: 11 Mar 2010 Posts: 19539

Always on USB, even if using the interrupt driven handler, you must actually retrieve data 'faster than it arrives', or problems will appear. The faster CPU, probably also has USB3 hardware. Though this switches down to USB2 rates, the latency on the machine will be lower, both from the faster CPU, and the more efficiently written drivers for USB3.
Lesson is to make sure that you are not delaying in the main control loop. If you need to delay for things, then use a state machine and interrupt driven clocks, not actual 'pauses'.