下面是一个获得 USB 键盘数据的例子【参考1】。原理上说，是将键盘切换为 Boot Protocol 这样就避免了需要具体解析HID的麻烦。
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/* MAX3421E USB Host controller LCD/keyboard demonstration */ |
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//#include <Spi.h> |
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#include "Max3421e.h" |
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#include "Usb.h" |
005 |
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/* keyboard data taken from configuration descriptor */ |
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#define KBD_ADDR 1 |
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#define KBD_EP 1 |
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#define KBD_IF 0 |
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#define EP_MAXPKTSIZE 8 |
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#define EP_POLL 0x0a |
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/**/ |
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//****************************************************************************** |
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// macros to identify special charaters(other than Digits and Alphabets) |
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//****************************************************************************** |
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#define BANG (0x1E) |
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#define AT (0x1F) |
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#define POUND (0x20) |
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#define DOLLAR (0x21) |
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#define PERCENT (0x22) |
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#define CAP (0x23) |
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#define AND (0x24) |
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#define STAR (0x25) |
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#define OPENBKT (0x26) |
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#define CLOSEBKT (0x27) |
026 |
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#define RETURN (0x28) |
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#define ESCAPE (0x29) |
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#define BACKSPACE (0x2A) |
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#define TAB (0x2B) |
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#define SPACE (0x2C) |
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#define HYPHEN (0x2D) |
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#define EQUAL (0x2E) |
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#define SQBKTOPEN (0x2F) |
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#define SQBKTCLOSE (0x30) |
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#define BACKSLASH (0x31) |
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#define SEMICOLON (0x33) |
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#define INVCOMMA (0x34) |
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#define TILDE (0x35) |
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#define COMMA (0x36) |
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#define PERIOD (0x37) |
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#define FRONTSLASH (0x38) |
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#define DELETE (0x4c) |
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/**/ |
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/* Modifier masks. One for both modifiers */ |
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#define SHIFT 0x22 |
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#define CTRL 0x11 |
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#define ALT 0x44 |
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#define GUI 0x88 |
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/**/ |
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/* "Sticky keys */ |
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#define CAPSLOCK (0x39) |
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#define NUMLOCK (0x53) |
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#define SCROLLLOCK (0x47) |
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/* Sticky keys output report bitmasks */ |
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#define bmNUMLOCK 0x01 |
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#define bmCAPSLOCK 0x02 |
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#define bmSCROLLLOCK 0x04 |
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/**/ |
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EP_RECORD ep_record[ 2 ]; //endpoint record structure for the keyboard |
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char buf[ 8 ] = { 0 }; //keyboard buffer |
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char old_buf[ 8 ] = { 0 }; //last poll |
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/* Sticky key state */ |
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bool numLock = false; |
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bool capsLock = false; |
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bool scrollLock = false; |
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bool line = false; |
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void setup(); |
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void loop(); |
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MAX3421E Max; |
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USB Usb; |
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void setup() { |
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Serial.begin( 9600 ); |
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Serial.println("Start"); |
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Max.powerOn(); |
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delay( 200 ); |
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} |
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void loop() { |
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Max.Task(); |
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Usb.Task(); |
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if( Usb.getUsbTaskState() == USB_STATE_CONFIGURING ) { |
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//wait for addressing state |
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kbd_init(); |
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Usb.setUsbTaskState( USB_STATE_RUNNING ); |
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} |
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if( Usb.getUsbTaskState() == USB_STATE_RUNNING ) { |
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//poll the keyboard |
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kbd_poll(); |
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} |
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} |
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/* Initialize keyboard */ |
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void kbd_init( void ) |
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{ |
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byte rcode = 0; //return code |
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/**/ |
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/* Initialize data structures */ |
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ep_record[ 0 ] = *( Usb.getDevTableEntry( 0,0 )); |
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//copy endpoint 0 parameters |
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ep_record[ 1 ].MaxPktSize = EP_MAXPKTSIZE; |
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ep_record[ 1 ].Interval = EP_POLL; |
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ep_record[ 1 ].sndToggle = bmSNDTOG0; |
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ep_record[ 1 ].rcvToggle = bmRCVTOG0; |
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Usb.setDevTableEntry( 1, ep_record ); |
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//plug kbd.endpoint parameters to devtable |
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/* Configure device */ |
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rcode = Usb.setConf( KBD_ADDR, 0, 1 ); |
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if( rcode ) { |
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Serial.print("Error attempting to configure keyboard. Return code :"); |
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Serial.println( rcode, HEX ); |
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while(1); //stop |
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} |
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/* Set boot protocol */ |
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rcode = Usb.setProto( KBD_ADDR, 0, 0, 0 ); |
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if( rcode ) { |
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Serial.print("Error attempting to configure boot protocol. Return code :"); |
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Serial.println( rcode, HEX ); |
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while( 1 ); //stop |
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} |
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delay(2000); |
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Serial.println("Keyboard initialized"); |
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} |
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/* Poll keyboard and print result */ |
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/* buffer starts at position 2, 0 is modifier key state and 1 is irrelevant */ |
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void kbd_poll( void ) |
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{ |
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char i; |
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static char leds = 0; |
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byte rcode = 0; //return code |
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/* poll keyboard */ |
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rcode = Usb.inTransfer( KBD_ADDR, KBD_EP, 8, buf ); |
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if( rcode != 0 ) { |
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return; |
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}//if ( rcode.. |
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for( i = 2; i < 8; i++ ) { |
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if( buf[ i ] == 0 ) { //end of non-empty space |
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break; |
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} |
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if( buf_compare( buf[ i ] ) == false ) { //if new key |
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switch( buf[ i ] ) { |
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case CAPSLOCK: |
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capsLock =! capsLock; |
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leds = ( capsLock ) ? leds |= bmCAPSLOCK : leds &= ~bmCAPSLOCK; |
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// set or clear bit 1 of LED report byte |
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break; |
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case NUMLOCK: |
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numLock =! numLock; |
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leds = ( numLock ) ? leds |= bmNUMLOCK : leds &= ~bmNUMLOCK; |
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// set or clear bit 0 of LED report byte |
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break; |
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case SCROLLLOCK: |
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scrollLock =! scrollLock; |
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leds = ( scrollLock ) ? leds |= bmSCROLLLOCK : leds &= ~bmSCROLLLOCK; |
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// set or clear bit 2 of LED report byte |
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break; |
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case DELETE: |
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line = false; |
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break; |
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case RETURN: |
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line =! line; |
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break; |
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default: |
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//Serial.print(HIDtoA( buf[ i ], buf[ 0 ] )); |
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break; |
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}//switch( buf[ i ... |
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Serial.print(buf[ i ],HEX); |
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Serial.print(\' \'); |
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Serial.println(buf[ 0 ],HEX); |
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rcode = Usb.setReport( KBD_ADDR, 0, 1, KBD_IF, 0x02, 0, &leds ); |
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if( rcode ) { |
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Serial.print("Set report error: "); |
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Serial.println( rcode, HEX ); |
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}//if( rcode ... |
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}//if( buf_compare( buf[ i ] ) == false ... |
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}//for( i = 2... |
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for( i = 2; i < 8; i++ ) { //copy new buffer to old |
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old_buf[ i ] = buf[ i ]; |
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} |
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} |
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/* compare byte against bytes in old buffer */ |
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bool buf_compare( byte data ) |
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{ |
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char i; |
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for( i = 2; i < 8; i++ ) { |
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if( old_buf[ i ] == data ) { |
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return( true ); |
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} |
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} |
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return( false ); |
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} |
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/* HID to ASCII converter. Takes HID keyboard scancode, returns ASCII code */ |
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byte HIDtoA( byte HIDbyte, byte mod ) |
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{ |
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/* upper row of the keyboard, numbers and special symbols */ |
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if( HIDbyte >= 0x1e && HIDbyte <= 0x27 ) { |
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if(( mod & SHIFT ) || numLock ) { //shift key pressed |
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switch( HIDbyte ) { |
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case BANG: return( 0x21 ); |
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case AT: return( 0x40 ); |
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case POUND: return( 0x23 ); |
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case DOLLAR: return( 0x24 ); |
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case PERCENT: return( 0x25 ); |
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case CAP: return( 0x5e ); |
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case AND: return( 0x26 ); |
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case STAR: return( 0x2a ); |
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case OPENBKT: return( 0x28 ); |
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case CLOSEBKT: return( 0x29 ); |
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}//switch( HIDbyte... |
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} |
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else { //numbers |
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if( HIDbyte == 0x27 ) { //zero |
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return( 0x30 ); |
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} |
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else { |
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return( HIDbyte + 0x13 ); |
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} |
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}//numbers |
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}//if( HIDbyte >= 0x1e && HIDbyte <= 0x27 |
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/**/ |
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/* number pad. Arrows are not supported */ |
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if(( HIDbyte >= 0x59 && HIDbyte <= 0x61 ) && |
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( numLock == true )) { // numbers 1-9 |
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return( HIDbyte - 0x28 ); |
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} |
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if(( HIDbyte == 0x62 ) && ( numLock == true )) { //zero |
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return( 0x30 ); |
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} |
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/* Letters a-z */ |
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if( HIDbyte >= 0x04 && HIDbyte <= 0x1d ) { |
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if((( capsLock == true ) && ( mod & SHIFT ) == 0 ) |
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|| (( capsLock == false ) && ( mod & SHIFT ))) { |
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//upper case |
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return( HIDbyte + 0x3d ); |
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} |
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else { //lower case |
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return( HIDbyte + 0x5d ); |
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} |
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}//if( HIDbyte >= 0x04 && HIDbyte <= 0x1d... |
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/* Other special symbols */ |
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if( HIDbyte >= 0x2c && HIDbyte <= 0x38 ) { |
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switch( HIDbyte ) { |
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case SPACE: return( 0x20 ); |
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case HYPHEN: |
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if(( mod & SHIFT ) == false ) { |
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return( 0x2d ); |
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} |
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else { |
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return( 0x5f ); |
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} |
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case EQUAL: |
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if(( mod & SHIFT ) == false ) { |
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return( 0x3d ); |
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} |
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else { |
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return( 0x2b ); |
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} |
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case SQBKTOPEN: |
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if(( mod & SHIFT ) == false ) { |
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return( 0x5b ); |
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} |
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else { |
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return( 0x7b ); |
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} |
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case SQBKTCLOSE: |
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if(( mod & SHIFT ) == false ) { |
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return( 0x5d ); |
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} |
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else { |
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return( 0x7d ); |
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} |
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case BACKSLASH: |
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if(( mod & SHIFT ) == false ) { |
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return( 0x5c ); |
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} |
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else { |
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return( 0x7c ); |
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} |
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case SEMICOLON: |
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if(( mod & SHIFT ) == false ) { |
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return( 0x3b ); |
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} |
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else { |
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return( 0x3a ); |
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} |
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case INVCOMMA: |
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if(( mod & SHIFT ) == false ) { |
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return( 0x27 ); |
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} |
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else { |
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return( 0x22 ); |
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} |
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case TILDE: |
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if(( mod & SHIFT ) == false ) { |
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return( 0x60 ); |
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} |
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else { |
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return( 0x7e ); |
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} |
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case COMMA: |
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if(( mod & SHIFT ) == false ) { |
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return( 0x2c ); |
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} |
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else { |
310 |
return( 0x3c ); |
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} |
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case PERIOD: |
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if(( mod & SHIFT ) == false ) { |
314 |
return( 0x2e ); |
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} |
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else { |
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return( 0x3e ); |
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} |
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case FRONTSLASH: |
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if(( mod & SHIFT ) == false ) { |
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return( 0x2f ); |
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} |
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else { |
324 |
return( 0x3f ); |
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} |
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default: |
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break; |
328 |
}//switch( HIDbyte.. |
329 |
}//if( HIDbye >= 0x2d && HIDbyte <= 0x38.. |
330 |
return( 0 ); |
331 |
} |
实验依然使用上一次的USB小键盘。上面的按键分布如下：
关于键值的介绍可以在【参考1】找到
NumLock OFF的情况下，各输出键值：
*输出三次62,相当于输出3个0
NumLock ON的情况下，各输出键值：
*输出三次62外加一个53
运行结果
本文完整代码下载 LCDkbd
参考：
1. https://github.com/felis/USB_Host_Shield/tree/master/examples/descriptor_parser USB_Host_Shield/examples/LCDkbd/ 本文原始代码
2. http://www.quadibloc.com/comp/scan.htm