话不多说，说多了都是泪，有图有真相（可能我看到的都是假象）……
希望坛友能指条明路，给点思路，反正什么都行啦，if 能跳过这个if

调试截图

流水源 发表于 2020-3-11 12:02
看看汇编，或者在变量定义前面加上volatile

汇编代码确实有问题，一条if语句前后汇编出了两段代码，第一段不正常，第二段正常，就是不知道为什么这样，我一会儿再加上volatile试试

1. static void vTaskLDS5461(void *pvParameters)
   
2. {
   
3. uint32_t i=0;
   
4. LDS5461_Config();
   
5. if(HAL_UART_Receive_DMA(&huart4,(uint8_t *)&(uart4_data.buf),256) != HAL_OK) //USART4接收
   
6. {
   
7. Error_Handler();
   
8. }
   
9. 
   
10. while(1)
    
11. {
    
12. if(uart4_data.flag == 1)
    
13. {
    
14. uart_data.ndtr = 256 - uart4_data.cndtr;
    
15. uart_data.flag=1;
    
16. for(i=0; i<uart_data.ndtr; i++)
    
17. {
    
18. uart_data.buf[i] = uart4_data.buf[i];
    
19. }
    
20. uart_data.buf[i&0x000000ff] = 0;
    
21. 
    
22. uart4_data.flag = 0;
    
23. if(HAL_UART_Receive_DMA(&huart4,(uint8_t *)&(uart4_data.buf),256) != HAL_OK) //USART4接收
    
24. {
    
25. Error_Handler();
    
26. }
    
27. 
    
28. Uart4_SendStr((char *)&uart_data.buf);
    
29. uart_data.flag = 0;
    
30. 
    
31. LDS5461_DisplayStr((const char *)&uart_data.buf);
    
32. }
    
33. 
    
34. vTaskSuspend(xHandleTaskLDS5461); //挂起此任务
    
35. }
    
36. }
    
37. 
    
38. vTaskLDS5461:
    
39. 0800647c: push {r3, r4, r5, r6, r7, lr}
    
40. 0800647e: bl 0x80003e0 <LDS5461_Config>
    
41. 08006482: mov.w r2, #256 ; 0x100
    
42. 08006486: ldr r1, [pc, #124] ; (0x8006504 <vTaskLDS5461+136>)
    
43. 08006488: ldr r0, [pc, #124] ; (0x8006508 <vTaskLDS5461+140>)
    
44. 0800648a: bl 0x80027a4 <HAL_UART_Receive_DMA>
    
45. 0800648e: cbnz r0, 0x8006498 <vTaskLDS5461+28>
    
46. <font color="#ff0000">134 if( uart4_data.flag == 1)</font>
    
47. 08006490: ldr r4, [pc, #112] ; (0x8006504 <vTaskLDS5461+136>)
    
48. 136 uart_data.ndtr = 256 - uart4_data.cndtr;
    
49. 08006492: ldr r5, [pc, #120] ; (0x800650c <vTaskLDS5461+144>)
    
50. 145 if(HAL_UART_Receive_DMA(&huart4,(uint8_t *)&(uart4_data.buf),256) != HAL_OK) //USART4接收
    
51. 08006494: ldr r6, [pc, #112] ; (0x8006508 <vTaskLDS5461+140>)
    
52. 08006496: b.n 0x80064b8 <vTaskLDS5461+60>
    
53. 129 Error_Handler();
    
54. 08006498: bl 0x800680c <Error_Handler>
    
55. 0800649c: b.n 0x8006490 <vTaskLDS5461+20>
    
56. 150 Uart4_SendStr((char *)&uart_data.buf);
    
57. 0800649e: mov r0, r5
    
58. 080064a0: bl 0x8006198 <Uart4_SendStr>
    
59. 151 uart_data.flag = 0;
    
60. 080064a4: movs r3, #0
    
61. 080064a6: str.w r3, [r5, #272] ; 0x110
    
62. 153 LDS5461_DisplayStr((const char *)&uart_data.buf);
    
63. 080064aa: mov r0, r5
    
64. 080064ac: bl 0x8000254 <LDS5461_DisplayStr>
    
65. 156 vTaskSuspend(xHandleTaskLDS5461); //挂起此任务
    
66. 080064b0: ldr r3, [pc, #92] ; (0x8006510 <vTaskLDS5461+148>)
    
67. 080064b2: ldr r0, [r3, #0]
    
68. 080064b4: bl 0x8003dc4 <vTaskSuspend>
    
69. <font color="#ff0000">134 if( uart4_data.flag == 1)</font>
    
70. 080064b8: ldr.w r3, [r4, #272] ; 0x110
    
71. 080064bc: cmp r3, #1
    
72. 080064be: bne.n 0x80064b0 <vTaskLDS5461+52>
    
73. 136 uart_data.ndtr = 256 - uart4_data.cndtr;
    
74. 080064c0: ldr.w r0, [r4, #260] ; 0x104
    
75. 080064c4: rsb r0, r0, #256 ; 0x100
    
76. 080064c8: str.w r0, [r5, #264] ; 0x108
    
77. 137 uart_data.flag=1;
    
78. 080064cc: str.w r3, [r5, #272] ; 0x110
    
79. 138 for(i=0; i<uart_data.ndtr; i++)
    
80. 080064d0: cbz r0, 0x80064e4 <vTaskLDS5461+104>
    
81. 080064d2: ldr r3, [pc, #48] ; (0x8006504 <vTaskLDS5461+136>)
    
82. 080064d4: ldr r2, [pc, #52] ; (0x800650c <vTaskLDS5461+144>)
    
83. 080064d6: adds r7, r0, r3
    
84. 140 uart_data.buf[i] = uart4_data.buf[i];
    
85. 080064d8: ldrb.w r1, [r3], #1
    
86. 080064dc: strb.w r1, [r2], #1
    
87. 138 for(i=0; i<uart_data.ndtr; i++)
    
88. 080064e0: cmp r3, r7
    
89. 080064e2: bne.n 0x80064d8 <vTaskLDS5461+92>
    
90. 142 uart_data.buf[i&0x000000ff] = 0;
    
91. 080064e4: uxtb r0, r0
    
92. 080064e6: movs r3, #0
    
93. 080064e8: strb r3, [r5, r0]
    
94. 144 uart4_data.flag = 0;
    
95. 080064ea: str.w r3, [r4, #272] ; 0x110
    
96. 145 if(HAL_UART_Receive_DMA(&huart4,(uint8_t *)&(uart4_data.buf),256) != HAL_OK) //USART4接收
    
97. 080064ee: mov.w r2, #256 ; 0x100
    
98. 080064f2: mov r1, r4
    
99. 080064f4: mov r0, r6
    
100. 080064f6: bl 0x80027a4 <HAL_UART_Receive_DMA>
     
101. 080064fa: cmp r0, #0
     
102. 080064fc: beq.n 0x800649e <vTaskLDS5461+34>
     
103. 147 Error_Handler();
     
104. 080064fe: bl 0x800680c <Error_Handler>
     
105. 08006502: b.n 0x800649e <vTaskLDS5461+34>
     
106. 08006504: adds r5, #200 ; 0xc8
     
107. 08006506: movs r0, #0
     
108. 08006508: adds r6, #224 ; 0xe0
     
109. 0800650a: movs r0, #0
     
110. 0800650c: adds r3, #96 ; 0x60
     
111. 0800650e: movs r0, #0
     
112. 08006510: movs r7, #108 ; 0x6c
     
113. 08006512: movs r0, #0
     

复制代码

注意一下优化等级吧，设为最低试试看