Objective Development Forums

It is possible to use an external supply. I'd recommend taking all the power from your own supply and leave the USB 5V unused. This violates the spec, I think, because your pull-up delivers current when the host is powered off, but that should not cause any real problems.

If your AVR tears down the USB supply, it must be broken (take more than 500 mA) or your USB port is broken.

BTW: I'd recommend 1k5 instead of 2k2 for the pull-up. You probably don't reach the threshold voltage on D- with 2k2 due to the current through the zener diodes.

The USART is disabled after reset. AVR-USB leaves it disabled unless you have turned on debugging.

Since the open fails, the device may be opened by another application on your machine. Don't know what error code 5 means, though.

I'm surprised to hear that pgm_read_byte_far() works in this case because the address is only 16 bit. If anybody has a good point WHY this works, we can add an #ifdef to usbportability.h (but on what condition?) or add a usbconfig.h option.

You need the latest version of bootloadHID for 12.8 MHz because all other boot loaders won't fit. And you need to wire D- to the interrupt because the continuous oscillator synchronization code is used.

This may be an issue with RC oscillator calibration. Which method of calibration do you use?

This is a chicken and egg problem. For the first time programming, you must use another programmer. If you have a friend who has a programmer, ask this friend. Otherwise make a web search for parallel port based programmers. They consist just of two connectors wired together. You need a PC with para...

If a master is present, there will be a SOF pulse every 1 ms on D-. If you connect D- to the interrupt and set USB_COUNT_SOF in usbconfig.h, you'll see whether usbSofCount increments.

The current version allows both, GPLv2 and GPLv3.

The value returned by GET_CONFIGURATION is the same as set with SET_CONFIGURATION. See the implementation in usbdrv.c. If the host is in sleep mode (you know that the host is sleeping when there are no frame pulses every 1 ms on D-), you can wake it with a SE0 condition: Tie D+ and D- to 0 for (I th...

This is a libusb-win32 issue. The info log comes directly from the libusb-win32 dll. Don't know whether there are versions without this log. The time to enumerate all USB devices depends on the implementation of libusb on the particular platform. You can implement a logic which searches on the "...

Sorry for not posting to this thread so far... I'm very interested in a CRC enabled version, but I currently don't have the time to put any work into it myself.

If you have questions about any details of the driver, please contact me through the support system.

When you change the Timer0 prescaler, you change the timing unless you also modify the code. With a prescaler of 64, you get ca. one interrupt every 1 ms, that should not cause problems when you declare the ISR as ISR_NOBLOCK. Disabling the Timer0 overflow interrupt only instead of cli() is a good i...

When the host initiates communication, the control transfer is one of your best options for low speed devices. Full speed devices would benefit from a bulk endpoint, though. In your case, just do a control-in, do your processing and then a control-out. 1 ms latency may be possible, but better measur...