Question

我会尽量更清楚：我需要将在RAM内存中计算出的3个浮点数转换为存储在RAM内存中不同位置的缓冲区：我编写了一个代码来执行此操作但是缓冲区没有以正确的方式填充：我只能读取一个值。这是RAM中用于计算var

的函数

#pragma CODE_SECTION(Calculatevar,".FLASHCODE")
void Calculatevar(volatile signed char *a,volatile signed char *b,volatile signed char *c)
{
float axg, ayg, azg; // x, y, and z axis readings of the accelerometer
volatile unsigned char a_x,a_y,a_z;

axg = (ax + 2083)/16131.0;
ayg = (ay + 208)/16131.0;
azg = (az + 204)/16131.0;

*a=axg*126;
*b=ayg*126;
*c=azg*126;
}

在main（）中我写了Calculatevar（＆amp; a，＆amp; b，＆amp; c）;定义volatile signed char a，b，c; 这是DMA功能：

   unsigned char DMA_transfer(buffer *pointer_buffer) //DATA WRITE/PUSH
{ int next = pointer_buffer->head + 1;
   if (next >= pointer_buffer->Num_Samples)
    next = 0;
   //buffer is full
    DMA0SZ =pointer_buffer->Num_Samples;
//    __data20_write_long((unsigned long) &DMA0SA,(unsigned long) &d1);
    __data20_write_long((unsigned long) &DMA0SA,(unsigned long) & a);
    __data20_write_long((unsigned long) &DMA0DA,(unsigned long) &pointer_buffer->buffer[pointer_buffer->head]);
    DMA0CTL |= DMAEN +DMAIE;                         // Enable DMA0
    DMA0CTL |= DMAREQ;                      // Trigger block transfer
    pointer_buffer->head = next;
    return 0;
}

我错过了什么？

Answer 1

对于初学者来说，第一个片段与DMA无关，并显示存储3个字符而不是浮点数。

其次，没有代码设置块传输，源/目标地址更改或字节（与字）传输。

如果没有其他代码配置DMA0，则一个字的默认单一传输模式只能正确传输一个值，因为在每个DMA0SZ传输次数后，源地址和目标地址都不会递增。

MSP430使用DMA传输存储在RAM

1 个答案: