Objective Development Forums

This error means that the boot loader size exceeds 0x844 bytes (that's 2116 bytes). You probably enabled debugging code or removed the -Os flag.

This must be a different issue. I have tested the 20 MHz version with test patterns which enforce bit stuffing at always the same bit. I have tested all bits this way.

Although it should be possible to use USB between two AVRs, I really doubt that you can save complexity this way. BTW: V-USB is the device side driver only. There's also a low speed host implementation available for the AVR, see the links section on our site. I would recommend TWI, SPI or UART commu...

I don't say it's impossible. Just that you should test on various platforms before you publish something. Control endpoints may be different from the bulk endpoints used in AVR-CDC. And even if it does not work on all platforms, it may be worth publishing. But you should add a note, otherwise you'll...

This code is in usbdrv/usbdrvasm12.inc or the respective module for your clock rate.

You did notice that there is a difference between the HCT125 and HCT126? The former has inverted enable pins while the latter has non-inverted ones. If you can't find the HCT126, you may try AVR-Doper with the USBasp hardware. This is a compile-time option. This hardware works without an external dr...

Regarding AVR-CDC: No, it does not work well. MANY people have problems where the device stops working all the sudden and the endpoint is stalled. This occurs most likely on Windows, other operating systems don't stall the endpoint on the first transmission error.

Did not take THAT long to track down: The unstuffing code for bit 6 was ca. one cycle too long. The error summed up if multiple unstuffings occurred in bit 6 until we were out of sync. You can fix the issue by changing the code in usbdrvasm16.inc: unstuff6: andi x2, USBMASK ;[03] ori x3, 1<<6 ;[04] ...

Regarding the transfer rate: This is all very fragile. It depends on timing, whether the AVR can supply a result within a certain amount of time. And the time frame depends on the host controllers, hubs and operating system. You may get high rates on one operating system and much less on another. Re...

In this respect, V-USB is in no way different than other USB devices. Most operating systems come with standard drivers for device classes and maybe some particular devices. If you can use one of these, you don't need your own driver.

Maybe you're mixing infos here. Most of the high registers are used by the compiler and you can use them in your inline assembler as well (if you tell the compiler that you modify them). However, if you need a static or global variable in a register, you must choose something below r8 (and not r0 an...

OK, I can reproduce the problem.

It will take some time to analyze it, though...

Interfacing MMC is no problem, of course. And it's no problem to implement an MMC driver and USB on the same device. But you can't implement the USB mass storage class.

Thanks for the info! The serial number is a good idea. We might spend some more PIDs for serial-number-based discrimination...

Is this new behavior in XP? If Windows caches the vendor and product string, our shared PID won't work. This used to work when I tested it...

Or do we still read the correct name if we use libusb? Or the method used to find HIDs?