5-6 串列埠模式0輸出埠擴充實習

串列埠  模式0 Clock frequency = 12 MHz/12 = 1 MHz

TXD RXD 8051 Turn on these switches: SW1_1: SW1_6: SW2_1: SW2_2: SW1_6

SH/LD 74165 operation 1 The FFs in 74165 are shifted out by the clock. The FFs in 74165 are updated (loaded) with new values.

74164: 8-Bit Serial-Input/Parallel-Output Shift Register

Related registers

SCON register SM2：設定RI=1的時機 模式 SM2 SM2 = 0 1 SM2 = 0 1 SM2 = 1  UART 接收到正確的停止位元才會令RI = 1 2 & 3 SM2 = 1  UART 接收到第九個資料位元RB8=1才會令RI = 1。 SM2可做多處理器通信之控制。

Because the serial port is now used as an output port SCON register SM0 SCON.7 SM1 SCON.6 SM2 SCON.5 REN SCON.4 To enable the serial port receiving REN = 0  UART not receiving REN = 1  UART receiving TB8 SCON.3 9th transmitted bit RB8 SCON.2 9th received bit or the stop bit TI SCON.1 TI = interrupt flag Mode 0: The 8th bit transmitted  TI = 1  Interrupt request to CPU Mode 1, 2, 3: The stop bit transmitted  TI = 1  Interrupt request to CPU RI SCON.0 RI = interrupt flag The 8th bit received  RI = 1  Interrupt request to CPU The stop bit received & SM2 ……. RI = 1  Interrupt request to CPU Because the serial port is now used as an output port

Programs 自我練習： 5-6-1-1 將程式中每一道 JNB TI,$ 與 CLR TI 指令去掉，再執行，觀看結果有無改變。 5-6-1-2 在程式執行過程中，分別將 SW1_1 與 SW1_6 撥至 OFF 位置，觀看執行結果有何變化。 5-6-1-3 在程式正常執行之下，以示波器觀察RXD與TXD接腳上之波形。 5-6-2-1 (Demo 2011.12.02) 設計一程式將一鍵盤中所鍵入之數字，透過串列埠，顯示在DS2七段顯示器上。

Programs Program 5-6-1 利用74164做I/O port 擴充，控制八個LED做五種變化的廣告燈控制。 1. 單一燈亮向右移動，執行四遍。 2.單一燈亮向左移動，執行四遍。 3.單一燈亮向左、右來回移動，執行二遍。 。 4. 四燈亮四燈滅交互顯示，執行四遍。 5. 由左右向中間移動，再往外移開，執行四遍。 Program 5-6-2 利用74164做I/O port 擴充，控制七段數字顯示器從00計數到99，再重覆。

TI becomes “1” when the 8th bit has been sent. 5-6-1程式重點 ORG 000H MOV SCON,#00000000B ; Set Mode 0 START: ;============================== MOV R5,#4 ;SET COUNTER MOV A,#00000001B NR1: RR A MOV SBUF,A ;SEND DATA JNB TI,$ ; TI = Transmission interrupt. ; TI will be set when the serial transmission through SBUF is done. CLR TI CALL DELAY JNB A.0,NR1 DJNZ R5,NR1  TI becomes “1” when the 8th bit has been sent.

ˋ Homework: JNB TI,$ CLR TI 這兩個指令去掉，程式是動作是否仍然正確？Why？

5-6-1 串列埠擴充做廣告燈控制

Program I5_6_1.ASM .SYMBOLS ON ORG 0000H JMP MAIN ORG 0050H MAIN: MOV SCON,#00000000B ;SET MODE 0 START: ;============================== MOV R5,#4 ;SET COUNTER MOV A,#00000001B NR1: RR A MOV SBUF,A ;SEND DATA JNB TI,$ CLR TI CALL DELAY JNB A.0,NR1 DJNZ R5,NR1 MOV A,#10000000B NL1: RL A JNB A.7,NL1 DJNZ R5,NL1 MOV R5,#2 ;SET COUNTER NR2: JNB A.0,NR2 NL2: JNB A.7,NL2 DJNZ R5,NR2 N3: MOV SBUF,#0F0H ;SEND DATA MOV SBUF,#0FH ;SEND DATA DJNZ R5,N3 N4: MOV A,#0 NDATA: PUSH A MOV DPTR,#TABLE MOVC A,@A+DPTR POP A INC A CJNE A,#7,NDATA DJNZ R5,N4 JMP START TABLE: DB 10000001B DB 01000010B DB 00100100B DB 00011000B DB 10000001B ; DELAY 0.1S DELAY: MOV R6,#200 DL1: MOV R7,#249 DJNZ R7,$ DJNZ R6,DL1 RET END

5-6-2 串列埠擴充做數字顯示控制

Program I5_6_2.ASM .SYMBOLS ON ORG 0000H JMP MAIN ORG 0050H MAIN: MOV SCON,#00000000B ;SET MODE 0 MOV A,#0 NEXT: MOV SBUF,A ;SEND DATA JNB TI,$ CLR TI CALL DELAY ADD A,#1 ;A=A+1 DA A ;BIN TO BCD JMP NEXT ;============================== ; DELAY 0.125S DELAY: MOV R6,#250 DL1: MOV R7,#249 DJNZ R7,$ DJNZ R6,DL1 RET END