PC键盘交流.doc

单片机系统与PC机键盘接口模块（仅供交流，时间有限，未加精琢，请多包涵）晓骥1 概述在微机系统中，输入是必不可少的，传统的输入方法是利用键盘，通过动态或静态、并行或串行方式输入。这些方法从理论到实践均非常成熟，但当输入按键较多时，在硬件设计和软件编程中总存在矛盾，通用性也差。而且对于不同的单片机系统需要进行专用的键盘硬件设计和编程调试，不但浪费硬件资源，而且在一定程度上使研究复杂化，耗费时间与精力，给研究工作带来诸多不便。标准PC键盘随着PC机的兴起而得到了广泛的应用，在工艺与技术上都已经相当成熟。它外观精美，工作稳定，价格低廉。标准PC键盘可利用的键码数多达近百个，随着制造工业的进步，其价格不断下降，现在一般键盘的零售价在40元左右，新的老式键盘只需1020元即可买到。特别是对于那些希望占用单片机的系统资源少而需要扩展的键数又多、仪器整体需要美观大方的设计者，其性能价格比显得更为优越。2 标准PC机键盘的工作原理键盘与计算机通过键盘插头相接，键盘插头有两种：大插头（5芯）和小插头（6芯）。两种键盘插头的外形图及各线定义如图（1）所示： 协议标准键盘与计算机采用双向通信方式，键盘可以发送数据给计算机，计算机也可以发送命令给键盘。计算机有最高优先权，可以在任何时候发命令给键盘。通信协议是标准的串行异步通信格式。1位起始位，8位数据位（LSB在先），1位奇校验位P，最后是1位停止位。数据格式如图（2）所示： LSBMSB起始位01234567P停止位当DATA和CLK同时为高电平时，键盘可以发送数据给计算机。CLK可以用作清除发送线。如果计算机将CLK拉为低电平，键盘将不发送数据，而是将要发送的数据放到发送缓冲区中，直到CLK变为高电平才开始发送数据。如果计算机将DATA拉低，则键盘在检测到这一变化时，将接收来自计算01234567P机的命令。图（3）给出了键盘发送一个字节的时序()。键盘先将DATA拉低，通知计算机准备接收数据。键盘在CLK的上升沿后改变数据，在下降沿时有效，可以被计算机读取。发送数据的时钟信号由键盘产生。图(4）给出了键盘接收一个字节的时序。为了避免在同一时刻发送数据，建议计算机先将CLK拉低大约60s以上，以此通知键盘不要发数据。然后计算机将DATA拉低，表明发送数据开始，并释放CLK，由键盘接管CLK并产生时钟信号。计算机在此时钟信号同步下发送数据。键盘接收数据是从检测到DATA变低开始的，然后在CLK下降沿读取起始位，并在CLK的每个下降沿读取后续数据。键盘在接收完校验位后，如果在下一个时钟周期检测到DATA处于空闲态（高电平），便会接受新数据并进行处理。在此期间，键盘将把DATA置成低电平，直到接受数据完成。如果收到校验位后，键盘检测到DATA没有处于空闲态，它将继续发送时钟信号直到DATA空闲。01234567P图（4） 键盘接收数据时序扫描码（要强调经过测试后得到的编码值）键盘电路正常工作时不断地扫描键盘矩阵。有按键，则确定按键位置之后以串行数据形式发送按键的扫描码给系统板键盘接口电路。按键的扫描码由接通扫描码和断开扫描码两部分组成。断开扫描码是在接通扫描码前加一个断开标志F0字节形成。键按下时，发送接通扫描码，简称通码；键松开时，则发送该键的断开扫描码，简称断码。若一直按下某键，则以按键重复率连续发送该键的接通扫描码。例如B键的接通扫描码是32H，断开扫描码是F0H、32H。B键被按下时，32H被发送出去，如果按住不放，则以按键重复率连续发送32H，直到该键释放，才发出断开扫描码F0H、32H。扫描码与按键的位置有关，与该键的ASCII码并无对应关系。在实际测试中得到的各按键的扫描码并无规律。命令 发送给键盘的命令1）FFH KB_RESET 复位键盘。2）FEH KB_RESEND 重新发送。3）F7HFDH 空操作（不使用）。4）F6H 设置缺省值。 5）F5H 设置缺省值和停止键盘。6）F4H KB_ENABLE 启动键盘。7）F3H KB_MAKE_BREAK 设置拍发速率/延时参数。8）EFF2H 空操作（不使用）。9）EEH KB_ECHO 回响命令。10）EDH LED_CMD 置位/复位LED指示器。接收键盘的命令1)FEH KB_RESEND_ACK 重新发送响应。 2）FAH KB_ACK 正常应答。3）00H KB_OVER_RUN 超限应答。4）FDH KB_FAL_ACK 诊断故障应答。5）AAH KB_OK 诊断正常应答。6）EEH KB_ECHO_ACK 对ECHO命令的应答。7）F0H KB_BREAK 断开扫描码前缀字节。断开扫描码占2B，第一个字节总是F0H，第二个字节同接通扫描码。WINDOWS操作系统对键盘的处理过程 对于键盘的输入，Windows调用键盘驱动程序把原始的硬件扫描码转换成虚拟键代码，然后将这些虚键码作为消息发送到应用程序。由于每个键盘键有两个扫描码即接通扫描码和断开扫描码，因此，每个键也有两个消息。当按键被按下时，产生消息WM_KEYDOWN；当按键被释放时产生消息WM_KEYUP。但是虚拟键代码不能提供足够的信息来获得字符输入。于是接下来，应用程序调用一个Windows API函数：TranslateMessage（），这一函数把虚拟键代码消息过滤成可打印字符。当发现可打印字符时，Windows生成一个新的消息VM_CHAR,并把它加到消息流中。这样，在应用程序的消息队列中，接收的每个WM_CHAR消息将前接一个WM_KEYDOWN消息，后续一个WM_KEYUP消息。从WM_CHAR消息中得到可打印字符输入，并可忽略有关虚键消息。对于不能创建可打印字符的键，必须依靠WM_KEYDOWN消息来检测这些键何时被按下。应用程序对感兴趣的击键信息提供了消息映射表输入项以及消息处理函数来处理它们。如果被激活，一个击键处理程序会接收到许多有关击键的信息，包括nChar、nRepCnt、和nFlags。其中nChar是被按下或释放的键的虚拟键代码。nRepCnt是消息中击键次数编码。nFlags中包含了按键的OEM扫描码（8位）和多个位标志。OEM扫描码是标识键盘BIOS键的8位值，本质上依赖硬件。字母AZ，az以及数字09的虚拟键代码与它们相应的ASCII码相同。关于按键的各种代码值请参看附表3 标准PC键盘输入模块的工作原理概述微机键盘上的单片微处理器在加电自动复位后，就开始扫描监视键盘电路，一旦有键被按下，键盘处理器就按照复位时的异步通信波特率缺省值，通过串行数据DATA OUT端和时钟定位CLOCK OUT端将按下键的扫描码发送出去。标准PC键盘输入模块中的2051通过它的中断功能接收扫描码，并将其外部中断设为下降沿触发方式。串行编码信号进入中断服务程序进行解码后，编码成一字节的WINDOWS虚拟键代码或两字节的OEM扫描码与ASCII码，通过并行口P1将输出的功能指令码送出。在模块中使用74LS244将发往并行口的功能码进行缓冲。发送时，将键值首先锁存在P1口上，为上位微机提供键值准备好的状态信号。在上位微机中，可查询此状态信号也可利用此状态信号申请中断。在它有效后，上位微机发出读缓冲器信号（负脉冲），便可通过三态缓冲器（74LS244）取得键值。在上位微机中，读缓冲器信号由某地址空间的片选信号与读信号共同产生。同时读缓冲器信号也作为触发器的清零信号，使触发器Q端为0，即ACK信号为0，系统可通过检测ACK信号状态来确定上位微机是否已取走键值。为了能更清楚地指示系统当前的工作状态，在硬件上加装了电源、解码、栈溢出、键值准备好等指示灯。中断解码的原理由于键盘的按键输入是随机的，为了能实时地响应，采用中断的方法进行解码。系统采用6M时钟，在系统启动后，T0就开始定时。在每次中断服务中，首先要关中断，停止定时并保护现场，然后判断定时器是否溢出，若是溢出，则可认为该次输入是一次新的输入，位计数清零并置按键有效标志KEY_VALID。若未溢出，则接收保存一位数据并移位，位计数加1。然后重新启动计数器，溢出标志TF0置0，返回等待下一位数据。详细的解码过程请参阅INT0中断解码程序流程图。FIFO栈的工作原理FIFO栈是程序中设置的缓冲区，它是一个按“先进现出”原则建立的循环队列，大小由程序设定。它有一个队列头指针，一个队列尾指针。队列为空时，头指针等于尾指针；进队列时，数据进入由队列尾指针指示的单元，同时队列尾指针增量，指向下一个单元：出队列时，数据从队列头指针指示的单元取出，同时队列头指针增量，指向下一个单元；当数据不断进入队列，使尾指针指向队列末端使，尾指针循环重新绕回队列始端。如果继续到尾指针与头指针再次相等，则表明队列已满，不能再存入数据。与上位单片机的交互过程在主程序中，每次新得到的键值都放在当前的FIFO栈尾，而每次系统向上位微机发送的都是栈首的键值。发送时，将键值首先锁存在P1口上，然后由P3.7和P3.5产生模拟的数据信号和时钟脉冲信号，将触发器（74LS74）置为1，端变为0，为上位微值准备好的状态信机提供键号。在上位微机中，可查询此状态信号也可利用此状态信号申请中断。在它有效后，上位微机发出读缓冲器信号（负脉冲），便可通过三态缓冲器（74LS244）取得键值。在上位微机中，读缓冲器信号由某地址空间的片选信号与读信号共同产生。同时读缓冲器信号也作为触发器的清零信号，使触发器Q端为0，即ACK信号为0，系统可通过检测ACK信号状态来确定上位微机是否已取走键值。 标准PC键盘输入模块的软件编程主程序如下左，中断接收键盘编码的服务程序如下右：以上流程做了简化处理，实际考虑问题要更多一些。4 标准PC键盘输入模块与上位单片微机的连接上位单片机与本模块的连接是使用接插件，可使用并行或串行方式，其定义如下：连接和编程非常简单，不再多述。此模块与系统的连接关系如图所示。由于本模块体积较小，亦可直接垂直安装在系统主板中。13附表：代码一览表(中间可能有误，正在排查)按键名称（按键位置排序）系统扫描码ASCIIWindows虚拟键代码备注下挡上挡ESC1 (01H)272727 (1BH)F159 (3BH)00112 (70H)F260 (3CH)00113 (71H)F361 (3DH)00114 (72H)F462 (3EH)00115 (73H)F563 (3FH00116 (74H)F664 (40H)00117 (75H)F765 (41H)00118 (76H)F866 (42H)00119 (77H)F967 (43H)00120 (78H)F1068 (44H)00121 (79H)F1100122 (7AH)F1200123 (7BH)41 (29H)96（60H）126 (7EH)192 (C0H)1!2 (02H)49 (31H)33 (21H)49 (31H)23 (03H)50 (32H)64 (40H)50 (32H)3#4 (04H)51 (33H)35 (23H)51 (33H)4$5 (05H)52 (34H)36 (24H)52 (34H)5%6 (06H)53 (35H)37 (25H)53 (35H)67 (07H)54 (36H)94 (5EH)54 (36H)7&8 (08H)55 (37H)38 (26H)55 (37H)8*9 (09H)56 (38H)42 (2AH)56 (38H)9(10 (0AH)57 (39H)40 (28H)57 (39H)0)11 (0BH)48 (30H)41 (29H)48 (30H)-_12 (0CH)45 (2DH)95 (5FH)189 (BDH)=+13 (0DH)61 (3DH)43 (2BH)187 (BBH)|43 (2BH)92 (5CH)124 (7CH)220 (DCH)BACK SPACE14 (0EH)8 (08H)8 (08H)8 (08H)TAB15 (0FH)9 (09H)9 (09H)9 (09H)Q16 (10H)113 (71H)81 (51H)81 (51H)W17 (11H)119 (77H)87 (57H)87 (57H)E18 (12H)101 (65H)69 (45H)69 (45H)R19 (13H)114 (72H)82 (52H)82 (52H)T20 (14H)116 (74H)84 (54H)84 (54H)Y21 (15H)121 (79H)89 (59H)89 (59H)U22 (16H)117 (75H)85 (55H)85 (55H)I23 (17H)105 (69H)73 (49H)73 (49H)O24 (18H)111 (6FH)79 (4FH)79 (4FH)P25 (19H)112 (70H)80 (50H)80 (50H)26 (20H)91 (5BH)123 (7BH)219 (DBH)27 (21H)93 (5DH)125 (7DH)221 (DDH)CAPS LOCK58 (3AH)0020 (14H)A30 (1EH)97 (61H)65 (41H)65 (41H)S31 (1FH)115 (73H)83 (53h)83 (53H)D32 (20H)100 (64H)68 (44H)68 (44H)F33 (21H)102 (66H)70 (46H)70 (46H)G34 (22H)103 (67H)71 (47H)71 (47H)H35 (23H)104 (68H)72 (48H)72 (48H)J36 (24H)106 (6AH)74 (4AH)74 (4AH)K37 (25H)107 (6BH)75 (4BH)75 (4BH)L38 (26H)108 (6CH)76 (4CH)76 (4CH);:39 (27H)59 (3BH)58 (3AH)186 (BAH)”40 (28H)39 (27H)34 (22H)222 (DEH)ENTER28 (1CH)13 (0DH)13 (0DH)13 (0DH)LEFT SHIFT42 (2AH)0016 (10H)Z44 (2CH)122 (7AH)90 (5AH)90 (5AH)X45 (2DH)120 (78H)88 (58H)88 (58H)C46 (2EH)99 (63H)67 (43H)67 (43H)V47 (2FH)118 (76H)86 (56H)86 (56H)B48 (30H)98 (62H)66 (42H)66 (42H)N49 (31H)110 (6EH)78 (4EH)78 (4EH)M50 (32H)109 (6DH)77 (4DH)77 (4DH),52 (34H)46 (2EH)62 (3EH)190 (BEH)/?53 (35H)47 (2FH)63 (3FH)191 (BFH)RIGHT SHIFT54 (36H)0016 (10H)LEFT CTRL29 (1DH)0017 (11H)LEFT WIN91 (5BH)0091 (5BH)LEFT ALT56 (38H)0018 (12H)SPACE57 (39H)32 (20H)32 (20H)32 (20H)RIGHT ALT56 (38H)0018 (12H)RIGHT WIN92 (5CH)0092 (5CH)APPLICATION93 (5DH)0093 (5DH)RIGHT CTRL29 (1DH)0017 (11H)PRINT SCREEN55 (37H)0044 (2CH)SCROLL LOCK70 (46H)00145 (91H)PAUSE BREAK69 (45H)0019 (13H)INSERT82 (52H)0045 (2DH)Num offNum onHOME71 (47H)0036 (24H)同上PAGE UP73 (49H)0033 (21H)同上DELETE83 (53H)0046 (2EH)同上END79 (4FH) 0035 (23H)同上PAGE DOWN81 (51H)0034 (22H)同上UP72 (48H)0038 (26H)LEFT75 (4BH)0037 (25H)DOWN80 (50H)0040 (28H)RIGHT77 (4DH)0039 (27H)NUM LOCK(KEYPAD)69 (45H)00144 (90H)/(KEYPAD)53 (35H)47 (2FH)47 (2FH)111 (6FH)*(KEYPAD)55 (37H)42 (2AH)42 (2AH)106 (6AH)-(KEYPAD)74 (4AH)45 (2DH)45 (2DH)109 (6DH)7 HOME(KEYPAD)71 (47H)55 (37H)055 (37H)0103 (67H)36 (24H)Num onNum off8 UP(KEYPAD)72 (48H)56 (38H)056 (38H)0104 (68H)38 (26H)同上9 PAGE UP(KEYPAD)73 (49H)57 (39H)057 (39H)0105 (69H)33 (21H)同上4 LEFT(KEYPAD)75 (4BH)52 (34H)052 (34H)0100 (64H)37 (25H)同上5(KEYPAD)76 (4CH)53 (35H)053 (35H)0101 (65H)12 (0CH)同上6 RIGHT(KEYPAD)77 (4DH)54 (36H)054 (36H)0102 (66H)39 (27H)同上+(KEYPAD)78 (4EH)43 (2BH)43 (2BH)107 (6BH)1 END(KEYPAD)79 (4FH)49 (31H)049 (31H)097 (61H)35 (23H)同上2 DOWN(KEYPAD)80 (50H)50 (32H)050 (32H)098 (62H)40 (28H)同上3 PAGE DOW(KEYPAD)N81 (51H)51 (33H)051 (33H)099 (63H)34 (22H)同上0 INS(KEYPAD)82 (52H)48 (30H)048 (30H)096 (60H)45 (2DH)同上. DEL(KEYPAD)83 (53H)46 (2EH)046 (2EH)0110 (6EH)46 (2EH)同上ENTER(KEYPAD)28 (1CH)13 (0DH)13 (0DH)13 (0DH)按键名称（按ASCII大小排序）系统扫描码ASCIIWindows虚拟键代码备注下挡上挡ESC127 (1BH)F159 (3BH)112 (70H)F260 (3CH)113 (71H)F361 (3DH)114 (72H)F462 (3EH)115 (73H)F563 (3FH116 (74H)F664 (40H)117 (75H)F765 (41H)118 (76H)F866 (42H)119 (77H)F967 (43H)120 (78H)F1068 (44H)121 (79H)F11122 (7AH)F12123 (7BH)BACK SPACE14 (0EH)8 (08H)8 (08H)8 (08H)TAB15 (0FH)9 (09H)9 (09H)9 (09H)”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|43 (2BH)92 (5CH)124 (7CH)220 (DCH)27 (21H)93 (5DH)125 (7DH)221 (DDH)41 (29H)96 (60H)126 (7EH)192 (C0H)A30 (1EH)97 (61H)65 (41H)65 (41H)B48 (30H)98 (62H)66 (42H)66 (42H)C46 (2EH)99 (63H)67 (43H)67 (43H)D32 (20H)100 (64H)68 (44H)68 (44H)E18 (12H)101 (65H)69 (45H)69 (45H)F33 (21H)102 (66H)70 (46H)70 (46H)G34 (22H)103 (67H)71 (47H)71 (47H)H35 (23H)104 (68H)72 (48H)72 (48H)I23 (17H)105 (69H)73 (49H)73 (49H)J36 (24H)106 (6AH)74 (4AH)74 (4AH)K37 (25H)107 (6BH)75 (4BH)75 (4BH)L38 (26H)108 (6CH)76 (4CH)76 (4CH)M50 (32H)109 (6DH)77 (4DH)77 (4DH)N49 (31H)110 (6EH)78 (4EH)78 (4EH)O24 (18H)111 (6FH)79 (4FH)79 (4FH)P25 (19H)112 (70H)80 (50H)80 (50H)Q16 (10H)113 (71H)81 (51H)81 (51H)R19 (13H)114 (72H)82 (52H)82 (52H)S31 (1FH)115 (73H)83 (53h)83 (53H)T20 (14H)116 (74H)84 (54H)84 (54H)U22 (16H)117 (75H)85 (55H)85 (55H)V47 (2FH)118 (76H)86 (56H)86 (56H)W17 (11H)119 (77H)87 (57H)87 (57H)X45 (2DH)120 (78H)88 (58H)88 (58H)Y21 (15H)121 (79H)89 (59H)89 (59H)Z44 (2CH)122 (7AH)90 (5AH)90 (5AH)CAPS LOCK58 (3AH)0020 (14H)ENTER28 (1CH)13 (0DH)13 (0DH)13 (0DH)LEFT SHIFT42 (2AH)0016 (10H)RIGHT SHIFT54 (36H)0016 (10H)LEFT CTRL29 (1DH)0017 (11H)LEFT WIN91 (5BH)0091 (5BH)LEFT ALT56 (38H)0018 (12H)SPACE57 (39H)32 (20H)32 (20H)32 (20H)RIGHT ALT56 (38H)0018 (12H)RIGHT WIN92 (5CH)0092 (5CH)APPLICATION93 (5DH)0093 (5DH)RIGHT CTRL29 (1DH)0017 (11H)PRINT SCREEN55 (37H)0044 (2CH)SCROLL LOCK70 (46H)00145 (91H)PAUSE BREAK69 (45H)0019 (13H)INSERT82 (52H)0045 (2DH)HOME71 (47H)0036 (24H)PAGE UP73 (49H)0033 (21H)DELETE83 (53H)0046 (2EH)END79 (4FH) 0035 (23H)PAGE DOWN81 (51H)0034 (22H)UP72 (48H)0038 (26H)LEFT75 (4BH)0037 (25H)DOWN80 (50H)0040 (28H)RIGHT77 (4DH)0039 (27H)NUM LOCK(KEYPAD)69 (45H)00144 (90H)/(KEYPAD)53 (35H)47 (2FH)47 (2FH)111 (6FH)*(KEYPAD)55 (37H)42 (2AH)42 (2AH)106 (6AH)-(KEYPAD)74 (4AH)45 (2DH)45 (2DH)109 (6DH)7 HOME(KEYPAD)71 (47H)55 (37H)055 (37H)0103 (67H)36 (24H)Num onNum off8 UP(KEYPAD)72 (48H)56 (38H)056 (38H)0104 (68H)38 (26H)同上9 PAGE UP(KEYPAD)73 (49H)57 (39H)057 (39H)0105 (69H)33 (21H)同上4 LEFT(KEYPAD)75 (4BH)52 (34H)052 (34H)0100 (64H)37 (25H)同上5(KEYPAD)76 (4CH)53 (35H)053 (35H)0101 (65H)12 (0CH)同上6 RIGHT(KEYPAD)77 (4DH)54 (36H)054 (36H)0102 (66H)39 (27H)同上+(KEYPAD)78 (4EH)43 (2BH)43 (2BH)107 (6BH)1 END(KEYPAD)79 (4FH)49 (31H)049 (31H)097 (61H)35 (23H)同上2 DOWN(KEYPAD)80 (50H)50 (32H)050 (32H)098 (62H)40 (28H)同上3 PAGE DOW(KEYPAD)N81 (51H)51 (33H)051 (33H)099 (63H)34 (22H)同上0 INS(KEYPAD)82 (52H)48 (30H)048 (30H)096 (60H)45 (2DH)同上. DEL(KEYPAD)83 (53H)46 (2EH)046 (2EH)0110 (6EH)46 (2EH)同上ENTER(KEYPAD)28 (1CH)13 (0DH)13 (0DH)13 (0DH)附：WINDOWS的虚拟键代码ConstantValueDescriptionvbKeyLButton1Left mouse buttonvbKeyRButton2Right mouse buttonvbKeyCancel3CANCEL keyvbKeyMButton4Middle mouse buttonvbKeyBack8BACKSPACE keyvbKeyTab9TAB keyvbKeyClear12CLEAR keyvbKeyReturn13ENTER keyvbKeyShift16SHIFT keyvbKeyControl17CTRL keyvbKeyMenu18MENU keyvbKeyPause19PAUSE keyvbKeyCapital20CAPS LOCK keyvbKeyEscape27ESC keyvbKeySpace32SPACEBAR keyvbKeyPageUp33PAGE UP keyvbKeyPageDown34PAGE DOWN keyvbKeyEnd35END keyvbKeyHome36HOME keyvbKeyLeft37LEFT ARROW keyvbKeyUp38UP ARROW keyvbKeyRight39RIGHT ARROW keyvbKeyDown40DOWN ARROW keyvbKeySelect41SELECT keyvbKeyPrint42PRINT SCREEN keyvbKeyExecute43EXECUTE keyvbKeySnapshot44SNAPSHOT keyvbKeyInsert45INS keyvbKeyDelete46DEL keyvbKeyHelp47HELP keyvbKeyNumlock144NUM LOCK keyKeyA Through KeyZ Are the Same as Their ASCII Equivalents: A Through ZConstantValueDesc