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change keyboard report descriptor for NKRO.

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It uses 1byte for modifiers and 15bytes(120bits) for keys now.
example_keyboards
tmk 14 years ago
parent 51f17f0231
commit 1ed336a064
4 changed files with 98 additions and 50 deletions
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71
USB_NKRO.txt
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@ -1,6 +1,6 @@
USB NKRO MEMO
=============
2010/12/07
2010/12/09
References
@ -9,6 +9,9 @@ USB - boot mode, NKRO, compatibility, etc...
http://geekhack.org/showthread.php?t=13162
NKey Rollover - Overview, Testing Methodology, and Results
http://geekhack.org/showwiki.php?title=NKey+Rollover+-+Overview+Testing+Methodology+and+Results
dfj's NKRO(2010/06)
http://geekhack.org/showpost.php?p=191195&postcount=251
http://geekhack.org/showthread.php?p=204389#post204389
Terminogy
@ -22,18 +25,26 @@ membrane
OS Support Status
-----------------
NKRO is possible at least relatively new OS.
Following OS supports both Extended and Bitmarp report.
USB NKRO is possible *without* a custom driver.
At least following OSes supports.
Windows7 64bit
WindowsXP
Windows2000 SP4
Ubuntu10.4(Linux 2.6)
MacOSX(To be tested)
Custom Driver for USB NKRO
--------------------------
NOT NEEDED
at least when using fllowing report formats on Windows, Linux or MacOSX.
USB NKRO methods
----------------
1. Virtual keyboards
Keyboard can increase its KRO by using virtual keyboards with Standard or Extended report.
If the keyboard has 2 virtul keyboard with Standard report(6KRO), it gets 12KRO.
If the keyboard has 2 virtual keyboard with Standard report(6KRO), it gets 12KRO.
Using this method means the keyboard is a composite device.
2. Exteded report
@ -70,28 +81,64 @@ Extended report is expected to be compatible with boot protocol.
Bitmap report can send at most 128keys by 16bytes and 256keys by 32bytes.
Bitmap report can achieve USB NKRO efficiently in terms of report size.
Bitmap report needs a deliberation for boot protocol implementation.
Compatibility Problem
---------------------
Bitmap report descriptor sample:
0x05, 0x01, // Usage Page (Generic Desktop),
0x09, 0x06, // Usage (Keyboard),
0xA1, 0x01, // Collection (Application),
// bitmap of modifiers
0x75, 0x01, // Report Size (1),
0x95, 0x08, // Report Count (8),
0x05, 0x07, // Usage Page (Key Codes),
0x19, 0xE0, // Usage Minimum (224),
0x29, 0xE7, // Usage Maximum (231),
0x15, 0x00, // Logical Minimum (0),
0x25, 0x01, // Logical Maximum (1),
0x81, 0x02, // Input (Data, Variable, Absolute), ;Modifier byte
// LED output report
0x95, 0x05, // Report Count (5),
0x75, 0x01, // Report Size (1),
0x05, 0x08, // Usage Page (LEDs),
0x19, 0x01, // Usage Minimum (1),
0x29, 0x05, // Usage Maximum (5),
0x91, 0x02, // Output (Data, Variable, Absolute),
0x95, 0x01, // Report Count (1),
0x75, 0x03, // Report Size (3),
0x91, 0x03, // Output (Constant),
// bitmap of keys
0x95, (REPORT_BYTES-1)*8, // Report Count (),
0x75, 0x01, // Report Size (1),
0x15, 0x00, // Logical Minimum (0),
0x25, 0x01, // Logical Maximum(1),
0x05, 0x07, // Usage Page (Key Codes),
0x19, 0x00, // Usage Minimum (0),
0x29, (REPORT_BYTES-1)*8-1, // Usage Maximum (),
0x81, 0x02, // Input (Data, Variable, Absolute),
0xc0 // End Collection
where REPORT_BYTES is a report size in bytes.
Considerations
--------------
Compatibility
boot protocol
minor/old system
Some BIOS doesn't send SET_PROTCOL request, a keyboard can't switch to boot protocol mode.
This may cuase a problem on a keyboard which uses other report than Standard.
Reactivity
USB polling time
OS/Driver processing time
Windows Problem
---------------
1. Windows accepts only 6keys in case of Standard report.
It should be able to send 6keys plus 8modifiers.
2. Windows accepts only 10keys in case of 16bytes Extended report.
It should be able to send 14keys plus 8modifiers.
3. Windows accepts only 18keys in case of 32bytes Extended report.
It should be able to send 30keys plus 8modifiers.
If keys are pressed in excess of the number, wrong keys are registered on Windows.
This problem will be reportedly fixed soon.(2010/12/05)
http://forums.anandtech.com/showpost.php?p=30873364&postcount=17

10
usb.c
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@ -173,6 +173,7 @@ static uint8_t PROGMEM keyboard2_hid_report_desc[] = {
0x05, 0x01, // Usage Page (Generic Desktop),
0x09, 0x06, // Usage (Keyboard),
0xA1, 0x01, // Collection (Application),
// bitmap of modifiers
0x75, 0x01, // Report Size (1),
0x95, 0x08, // Report Count (8),
0x05, 0x07, // Usage Page (Key Codes),
@ -181,18 +182,17 @@ static uint8_t PROGMEM keyboard2_hid_report_desc[] = {
0x15, 0x00, // Logical Minimum (0),
0x25, 0x01, // Logical Maximum (1),
0x81, 0x02, // Input (Data, Variable, Absolute), ;Modifier byte
0x95, 0x01, // Report Count (1),
0x75, 0x08, // Report Size (8),
0x81, 0x03, // Input (Constant), ;Reserved byte
// LED output report
0x95, 0x05, // Report Count (5),
0x75, 0x01, // Report Size (1),
0x05, 0x08, // Usage Page (LEDs),
0x19, 0x01, // Usage Minimum (1),
0x29, 0x05, // Usage Maximum (5),
0x91, 0x02, // Output (Data, Variable, Absolute), ;LED report
0x91, 0x02, // Output (Data, Variable, Absolute),
0x95, 0x01, // Report Count (1),
0x75, 0x03, // Report Size (3),
0x91, 0x03, // Output (Constant), ;LED report padding
0x91, 0x03, // Output (Constant),
// bitmap of keys
0x95, KBD2_REPORT_KEYS*8, // Report Count (),
0x75, 0x01, // Report Size (1),
0x15, 0x00, // Logical Minimum (0),

1
usb_keyboard.c
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@ -211,6 +211,7 @@ static inline int8_t _send_report(usb_keyboard_report_t *report, uint8_t endpoin
UENUM = endpoint;
}
UEDATX = report->mods;
if (!usb_keyboard_nkro)
UEDATX = 0;
for (uint8_t i = keys_start; i < keys_end; i++) {
UEDATX = report->keys[i];

2
usb_keyboard.h
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@ -18,7 +18,7 @@
#define KBD2_ENDPOINT 5
#define KBD2_SIZE 16
#define KBD2_BUFFER EP_DOUBLE_BUFFER
#define KBD2_REPORT_KEYS (KBD2_SIZE - 2)
#define KBD2_REPORT_KEYS (KBD2_SIZE - 1)
#endif
#if defined(KBD2_REPORT_KEYS) && KBD2_REPORT_KEYS > KBD_REPORT_KEYS

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