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usb keyboard auto repeat / typematic

 
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guy



Joined: 21 Oct 2005
Posts: 297

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usb keyboard auto repeat / typematic
PostPosted: Tue Feb 03, 2015 9:58 am     Reply with quote
I need to implement a keyboard with the USB HID library. I have done it before but now I need to add auto repeat / typematic (when a key is held down it repeats itself). Is there an option for that or do I have to manually program it?
Thanks!!
guy



Joined: 21 Oct 2005
Posts: 297

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solution!
PostPosted: Thu Feb 05, 2015 1:21 pm     Reply with quote
Darren from CCS tech support helped me with this one so I'll share it with you:
Quote:
While the key is held down the BIOS and OS handle what to do.

So the auto repeat is handled in the BIOS/Windows. I looked into the example code in ex_usb_keyboard.c and saw that in each iteration usb_keyboard_task() sends either a character or an empty array which signals that no key is pressed.
Code:

/////////////////////////////////////////////////////////////////////////////
//
// usb_keyboard_task()
//
// Sends a packet of keyboard data.  The protocol was specified in the HID
// report descriptor (see usb_desc_kbmouse.h), and is:
//     tx_msg[0] = modifier (see kb_modifier_t)
//     tx_msg[1] = const 0
//     tx_msg[2:6] = an array of held down keys.  a=4, b=5, etc.
//                   if msg[2:7]={0} then no keys are held down
//
//     rx_msg[0] = 5bit bitmap of led status
//
/////////////////////////////////////////////////////////////////////////////


What I did is to make tx_msg a global array that is NOT cleared each time but instead keeps track of the pressed keys (in index 2-6 of the array). When a key is released the suitable entry in the array is set to 0 which signals Key Released. Works great! My code is a little sloppy so I didn't upload it but let me know if someone needs actual code.
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