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一、实现串口通信
1.1创建代码 建立一个.s文件 1.2代码部分 ;RCC??????? RCC_BASE EQU 0x40021000 RCC_CR EQU (RCC_BASE + 0x00) RCC_CFGR EQU (RCC_BASE + 0x04) RCC_CIR EQU (RCC_BASE + 0x08) RCC_APB2RSTR EQU (RCC_BASE + 0x0C) RCC_APB1RSTR EQU (RCC_BASE + 0x10) RCC_AHBENR EQU (RCC_BASE + 0x14) RCC_APB2ENR EQU (RCC_BASE + 0x18) RCC_APB1ENR EQU (RCC_BASE + 0x1C) RCC_BDCR EQU (RCC_BASE + 0x20) RCC_CSR EQU (RCC_BASE + 0x24) ;AFIO??????? AFIO_BASE EQU 0x40010000 AFIO_EVCR EQU (AFIO_BASE + 0x00) AFIO_MAPR EQU (AFIO_BASE + 0x04) AFIO_EXTICR1 EQU (AFIO_BASE + 0x08) AFIO_EXTICR2 EQU (AFIO_BASE + 0x0C) AFIO_EXTICR3 EQU (AFIO_BASE + 0x10) AFIO_EXTICR4 EQU (AFIO_BASE + 0x14) ;GPIOA??????? GPIOA_BASE EQU 0x40010800 GPIOA_CRL EQU (GPIOA_BASE + 0x00) GPIOA_CRH EQU (GPIOA_BASE + 0x04) GPIOA_IDR EQU (GPIOA_BASE + 0x08) GPIOA_ODR EQU (GPIOA_BASE + 0x0C) GPIOA_BSRR EQU (GPIOA_BASE + 0x10) GPIOA_BRR EQU (GPIOA_BASE + 0x14) GPIOA_LCKR EQU (GPIOA_BASE + 0x18) ;GPIO C??? GPIOC_BASE EQU 0x40011000 GPIOC_CRL EQU (GPIOC_BASE + 0x00) GPIOC_CRH EQU (GPIOC_BASE + 0x04) GPIOC_IDR EQU (GPIOC_BASE + 0x08) GPIOC_ODR EQU (GPIOC_BASE + 0x0C) GPIOC_BSRR EQU (GPIOC_BASE + 0x10) GPIOC_BRR EQU (GPIOC_BASE + 0x14) GPIOC_LCKR EQU (GPIOC_BASE + 0x18) ;??1?? USART1_BASE EQU 0x40013800 USART1_SR EQU (USART1_BASE + 0x00) USART1_DR EQU (USART1_BASE + 0x04) USART1_BRR EQU (USART1_BASE + 0x08) USART1_CR1 EQU (USART1_BASE + 0x0c) USART1_CR2 EQU (USART1_BASE + 0x10) USART1_CR3 EQU (USART1_BASE + 0x14) USART1_GTPR EQU (USART1_BASE + 0x18) ;NVIC????? NVIC_BASE EQU 0xE000E000 NVIC_SETEN EQU (NVIC_BASE + 0x0010) ;SETENA?????????? NVIC_IRQPRI EQU (NVIC_BASE + 0x0400) ;??????????????? NVIC_VECTTBL EQU (NVIC_BASE + 0x0D08) ;??????????? NVIC_AIRCR EQU (NVIC_BASE + 0x0D0C) ;????????????????? SETENA0 EQU 0xE000E100 SETENA1 EQU 0xE000E104 ;SysTick????? SysTick_BASE EQU 0xE000E010 SYSTICKCSR EQU (SysTick_BASE + 0x00) SYSTICKRVR EQU (SysTick_BASE + 0x04) ;FLASH????????? FLASH_ACR EQU 0x40022000 ;SCB_BASE EQU (SCS_BASE + 0x0D00) MSP_TOP EQU 0x20005000 ;?????? PSP_TOP EQU 0x20004E00 ;??????? BitAlias_BASE EQU 0x22000000 ;????????? Flag1 EQU 0x20000200 b_flas EQU (BitAlias_BASE + (0x200*32) + (0*4)) ;??? b_05s EQU (BitAlias_BASE + (0x200*32) + (1*4)) ;??? DlyI EQU 0x20000204 DlyJ EQU 0x20000208 DlyK EQU 0x2000020C SysTim EQU 0x20000210 ;???? Bit0 EQU 0x00000001 Bit1 EQU 0x00000002 Bit2 EQU 0x00000004 Bit3 EQU 0x00000008 Bit4 EQU 0x00000010 Bit5 EQU 0x00000020 Bit6 EQU 0x00000040 Bit7 EQU 0x00000080 Bit8 EQU 0x00000100 Bit9 EQU 0x00000200 Bit10 EQU 0x00000400 Bit11 EQU 0x00000800 Bit12 EQU 0x00001000 Bit13 EQU 0x00002000 Bit14 EQU 0x00004000 Bit15 EQU 0x00008000 Bit16 EQU 0x00010000 Bit17 EQU 0x00020000 Bit18 EQU 0x00040000 Bit19 EQU 0x00080000 Bit20 EQU 0x00100000 Bit21 EQU 0x00200000 Bit22 EQU 0x00400000 Bit23 EQU 0x00800000 Bit24 EQU 0x01000000 Bit25 EQU 0x02000000 Bit26 EQU 0x04000000 Bit27 EQU 0x08000000 Bit28 EQU 0x10000000 Bit29 EQU 0x20000000 Bit30 EQU 0x40000000 Bit31 EQU 0x80000000 ;??? AREA RESET, DATA, READONLY DCD MSP_TOP ;?????? DCD Start ;???? DCD NMI_Handler ;NMI Handler DCD HardFault_Handler ;Hard Fault Handler DCD 0 DCD 0 DCD 0 DCD 0 DCD 0 DCD 0 DCD 0 DCD 0 DCD 0 DCD 0 DCD 0 DCD SysTick_Handler ;SysTick Handler SPACE 20 ;????20?? ;??? AREA |.text|, CODE, READONLY ;????? ENTRY ;??????????? Start ;?????? ldr r0, =RCC_CR ldr r1, [r0] orr r1, #Bit16 str r1, [r0] ;???????? ;????8M?? ClkOk ldr r1, [r0] ands r1, #Bit17 beq ClkOk ;???????? ldr r1,[r0] orr r1,#Bit17 str r1,[r0] ;FLASH??? ldr r0, =FLASH_ACR mov r1, #0x00000032 str r1, [r0] ;??PLL??????7,HSE????? ldr r0, =RCC_CFGR ldr r1, [r0] orr r1, #(Bit18 :OR: Bit19 :OR: Bit20 :OR: Bit16 :OR: Bit14) orr r1, #Bit10 str r1, [r0] ;??PLL??? ldr r0, =RCC_CR ldr r1, [r0] orr r1, #Bit24 str r1, [r0] PllOk ldr r1, [r0] ands r1, #Bit25 beq PllOk ;??PLL???????? ldr r0, =RCC_CFGR ldr r1, [r0] orr r1, #(Bit18 :OR: Bit19 :OR: Bit20 :OR: Bit16 :OR: Bit14) orr r1, #Bit10 orr r1, #Bit1 str r1, [r0] ;??RCC???? ldr r0, =RCC_APB2ENR mov r1, #(Bit14 :OR: Bit4 :OR: Bit2) str r1, [r0] ;PA9??0??? ldr r0, =GPIOA_CRH ldr r1, [r0] orr r1, #(Bit4 :OR: Bit5) ;PA.9????,????50MHz orr r1, #Bit7 and r1, #~Bit6 ;10:?????????? str r1, [r0] ldr r0, =USART1_BRR mov r1, #0x271 str r1, [r0] ;?????-> 115200 ldr r0, =USART1_CR1 mov r1, #0x200c str r1, [r0] ;USART????? ??????? ;71 02 00 00 2c 20 00 00 ;AFIO ???? ;Systick ???? ldr r0, =SYSTICKRVR ;Systick??? mov r1, #9000 str r1, [r0] ldr r0, =SYSTICKCSR ;??,??Systick mov r1, #0x03 str r1, [r0] ;??????????? ldr r0, =PSP_TOP ;??????? msr psp, r0 mov r0, #3 msr control, r0 ;???SRAM??? mov r1, #0 ldr r0, =Flag1 str r1, [r0] ldr r0, =DlyI str r1, [r0] ldr r0, =DlyJ str r1, [r0] ldr r0, =DlyK str r1, [r0] ldr r0, =SysTim str r1, [r0] ;??? main ldr r0, =Flag1 ldr r1, [r0] tst r1, #Bit1 ;SysTick??0.5s,??bit 1 beq main ;0.5s??????? ;0.5s?????? ldr r0, =b_05s ;??????0.5s?? mov r1, #0 str r1, [r0] mov r0, #'H' bl send_a_char mov r0, #'e' bl send_a_char mov r0, #'l' bl send_a_char mov r0, #'l' bl send_a_char mov r0, #'o' bl send_a_char mov r0, #' ' bl send_a_char mov r0, #'W' bl send_a_char mov r0, #'o' bl send_a_char mov r0, #'r' bl send_a_char mov r0, #'l' bl send_a_char mov r0, #'d' bl send_a_char mov r0, #'n' bl send_a_char b main ;??? ??1?????? send_a_char push {r0 - r3} ldr r2, =USART1_DR str r0, [r2] b1 ldr r2, =USART1_SR ldr r2, [r2] tst r2, #0x40 beq b1 ;????(Transmission complete)?? pop {r0 - r3} bx lr ;???? NMI_Handler bx lr HardFault_Handler bx lr SysTick_Handler ldr r0, =SysTim ldr r1, [r0] add r1, #1 str r1, [r0] cmp r1, #500 bcc TickExit mov r1, #0 str r1, [r0] ldr r0, =b_05s ;????500? ????????? ??0.5s??? ;?????1 mov r1, #1 str r1, [r0] TickExit bx lr ALIGN ;????????NOP??,???????????????? END 然后生成.h文件,编译无错误 1.3实现 二、串口通信仿真波形图 2.1设置 Options for target 2.2调试观察波形 进入调试界面选择逻辑分析仪 进入view中选择 把圈起来的拉进去 点击以下按键 随后点击run运行 最后得到波形图 三、流水灯仿真调试 前置步骤与上一节相同 选择以下几个 最后点run开始运行可得 四、总结 这次实验整体围绕USART串口输出的使用,实现了外部设备与处理器的通信。 |
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