看了移植文档，如果系统支持DMA，使用MDA会更好。可是DMA一般用于定长数据传输，CC3100的SPI传输不单是数据，还有配置什么的，这些数据的长度都不一，那怎么用DMA，大家有什么好的建议吗？
If your system has DMA you should consider to use it in order to increase the utilization
of the communication channel
If you have enough memory resources you should consider using a buffer to increase the
efficiency of the write operation
