Objective Development Forums

ulao wrote:level it bee unless you need to borrow more power. There is no "correct entry" it just depends on what you need. For example if you get power exceeded, then up it.

So how is that parameter used by the device or host? My understand is it is useful for something since it is a required.

Sorry if this has been asked.Is the USB_CFG_MAX_BUS_POWER parameter important? Is there any rule of thumb to estimate it? Thanks.
-Xiangrui

I don't have experience with those MCUs. But most MCUs allow higher frequency than specified. I played Atmega8L (says 8M) and Atmega168 (says 10M) at 12MHz, and both worked fine.

That won't work, since the data lines are pulled up or down. If you are not comfortable with the hardware, I recommend to start with some simple working hardware, such as the one I posted at http://forums.obdev.at/viewtopic.php?f=8&t=6848 I'm a beginner in micro-controller and now i'm trying to ...

I played with several usbasp programmers based on m . Although the firmware is the same, there are different makers, so the hardware can be slightly different. I found it is a cheap and convenient piece of hardware to play with the V-USB firmware. It has two LEDs for quick firmware test. Most have 4...

The only thing I can think about is the problem at connection of USB D+ to INT0.

It is always good to have some extra space. Try to use a chip with larger flash. It is quite common that you may like to add something in the future.

In the readme file under hid-custom-rq example folder, "Please note that you should install the filter version of libusb-win32 to take full advantage or [of?] this mode. The device driver version only has access to devices which have been registered for it with a *.inf file. The filter version ...

Did you also connect D+ to PD2 as required?

Are those bits for atmega16? You would try something like 0x80 and 0x9f for high and low fuse respectively. -Xiangrui Yes i have used the exact schematic except, instead of 2 single axis accelerometer I have used a 2 axis accelerometer breakout board and i have used a different transceiver. The HID ...

Are you sure it is right to connect oscillator to only XTAL1?

The CRC error is due to the data size is wrong. With correct data size, the HID feature Get/Set works fine, although the HIDAPI testgui still gives continuous "hid_read() returned error" when it connects to the device.

"sei();" is simply to enable global interrupt, right? It is already enabled in V-USB. Why do we need to do it again inside interrupt? Thanks. -Xiangrui I've used timer interrupts to control step motors without an issue for the V-USB connection. Without enabling interrupts in the timer. If ...

I got help from the Psychtoolbox developer. And I understand I don't have to open the device, but can use HID report to control and query a device. Here is the reply. "PsychHID on both Linux and Windows uses libusb-1.0 for low-level usb control transfers." For report related stuff, "i...

I am playing with the wonderful V-USB. With an atmega8 and a breadboard, I successfully made HIDkeys, hid-data and AVR-Doper work. What I like to build is a simple USB device which controls 2 or more TTL output. I also have some experience with AVR, so this should be easy. My difficulty is to figure...