There still seems to be a lot of traffic to my V-USB tutorials, so I thought I’d write a short follow-up post on USB keyboards. I already did a USB HID mouse post earlier, so you might want to check that out to understand a bit about HID descriptors and associated V-USB settings (in short, human interface devices send a binary descriptor to PC telling what kind of “reports” they send to the host on user activities).
As a basic setup, you’ll need a working V-USB circuit with one switch and one LED attached. Here, I’m using ATtiny2313 with the LED wired to PB0 and switch to PB1. The ATtiny is using 20 MHz crystal, so if you’re following my USB tutorial series and have that circuit at hand, remember to change that frequency in
usbconfig.c before trying this out. Note the cool breadboard header I have, there will be more posts about that one to follow soon!
Continue reading USB HID keyboard with V-USB
Wow, my AVR ATtiny USB tutorial here I got featured in Hack a Day! Motivated by the influx of readers, I decided to find out how to make a USB HID (human interface device) mouse.
V-USB examples already contain an example of this, so I digged in to see what is different in
usbconfig.h compared to the one we finished in my tutorial. It seems only a few things need changing:
USB_CFG_HAVE_INTRIN_ENDPOINT needs to be set to have an additional endpoint
USB_CFG_INTR_POLL_INTERVAL set to 100 ms instead of 10 in template
USB_CFG_IMPLEMENT_FN_WRITE is not needed, nor is …FN_READ (define both to 0)
- Device ID and name need to be changed. I’ll just use the same ID as they did
USB_CFG_DEVICE_CLASS is set to 0, not 0xff
USB_CFG_INTERFACE_CLASS set to 3 instead of 0
USB_CFG_HID_REPORT_DESCRIPTOR_LENGTH defined to match the structure’s length
That’s it! So here are the defines I changed:
#define USB_CFG_HAVE_INTRIN_ENDPOINT 1
#define USB_CFG_INTR_POLL_INTERVAL 100
#define USB_CFG_IMPLEMENT_FN_WRITE 0
#define USB_CFG_IMPLEMENT_FN_READ 0
#define USB_CFG_DEVICE_ID 0xe8, 0x03
#define USB_CFG_DEVICE_NAME 'M', 'o', 'u', 's', 'e'
#define USB_CFG_DEVICE_NAME_LEN 5
#define USB_CFG_DEVICE_CLASS 0
#define USB_CFG_INTERFACE_CLASS 3
#define USB_CFG_HID_REPORT_DESCRIPTOR_LENGTH 52
OK. So what about
main.c? Turns out the changes are rather straightforward:
Continue reading V-USB tutorial continued: HID mouse