Objective Development Forums

This may have something to do with voltage levels or it may be more complex. But it's hard to say without a capture of the on-the-wire communication.

As far as I know, there is no other way. Please note that when you disconnect, you must stay disconnected for at least 300 ms. Otherwise the host may not detect the disconnect. As an alternative, you may trigger the reconnect only when you know that the connection to the PC was lost. E.g. if the hos...

The macro USB_PROP_LENGTH() is expected to return the descriptor length, not the string length. Your fix with len = 2 * (len + 1) works for string descriptors, but not for HID, report, device, endpoint and other descriptors. You should rather define #define USB_CFG_DESCR_PROPS_STRING_SERIAL_NUMBER (...

For large scale professional products, I'd really recommend chips with built-in hardware USB. You can NEVER become USB compliant with V-USB because the AVR does not meet the electrical specifications. Regarding CodeVision: I tried to port V-USB to this development environment, but there are some fun...

Thanks for the tutorial!

Please consider adding the tutorial or a link to it to http://vusb.wikidot.com.

Shold be fixed now.

I can confirm that EMI (Electro Magnetic Interference) is a problem with AVRs. Switching an inductive load can cause the PC disconnect. Analysis has shown that the AVR itself performs kind of half of a reset. Some parts of the chip go into reset status, others don't. I have seen this even on project...

You can replace every USB descriptor with your own version by defining USB_CFG_DESCR_PROPS_DEVICE, USB_CFG_DESCR_PROPS_CONFIGURATION and so on. You can supply your own version in flash memory or as return value from a function call. Don't know whether you actually need a composite device, though. Yo...

Christian, usbConfiguration should be cleared during a reset condition (usbPoll(), where usbDevice Addr is cleared). I considered this, but it costs two bytes of code space. Some boot loaders fit extremely tight and the two bytes may be a problem there. On the other hand, usbConfiguration is rarely...

You can use one AVR just as an interface to USB, but you can also implement your application firmware on it, depending on your real time constraints. In general, you don't need a second AVR. When you build your first Metaboard, you need to flash the firmware somehow. Once the loader is flashed, you ...

The clean method would be to use your own usbFunctionRead() and wait until bytesRemaining is zero. If you also want to wait until the host has read the last chunk, use Grendel's trick. If you want to use the built-in usbFunctionRead for static memory blocks, have a look at usbMsgPtr. If it has advan...

This latest version should work, unless parts of your software suffer under the large delay of this construct. I noticed you compute (void *)&buffer + intvalue. Gcc probably handles it correctly, but strictly speaking, a void pointer has no size and adding a value to it is nonsense. You probably...

We have released a new version of the driver yesterday. I doubt that it fixes your particular problem, though, since it fixes bugs in the 12.8 and 16 MHz modules only. If the bugs occur with all clock frequencies, the problem must be in the common code, not in the low level bitbanging stuff. It's ei...

Thanks for the hint! USB 1.0 declared the bmAttributes field as with values

while USB 1.1 seems to define USBATTR_BUSPOWER as mandatory.

I'll change the driver accordingly. Thanks!

This is USBaspLoader, right? See bootloaderconfig.h. There are several options which affect code size. If you don't implement EEPROM access, you should save enough to fit into the boot area.