如何减少线程时间片？

你好，
在多线程FX3项目中，一个线程的任务是通过每160个USEC通过SPI端口从ADC获得样本。
每个样本读取意味着一个4字节的传输到ADC，然后是3字节的读取。
当另一个线程开始时，在执行期间，ADC不被读取，因此FX3丢失了一些样本。
最小可用时间片是1毫秒：有可能减少它吗？
来自ADC的EOC是下降沿信号，并且该信号连接到FX3GPIO引脚，以便将其链接到ISR。
我的目的是在ISR内部开始基于DMA的读/写SPI传输，但是我不理解如何在不涉及CPU的情况下完成它。
有可能做到这一点吗？
DMA Trasver块的最小维度是16字节：如何减少？
感谢和问候
马西莫利吉奥



     以下为原文
  Hi,
in a multi-thread FX3 project, a task of one thread is to get samples from an ADC every 160 usec thru SPI port.
Every sample read means a 4 bytes transmission to ADC and then a 3 bytes reading.
When another thread starts, during its execution time the ADC is not read, so FX3 loses some samples.
The minimum available time slice is 1 ms: is it possible to reduce it?

The EOC from ADC is a falling edge signal, and this signal is connected to a FX3 GPIO pin in order to link to it an ISR.
My purpose is to start inside the ISR a read/write SPI transmission based on DMA, but i didn't understand yet how to do it without involving CPU.
Is it possible to do it?

The smallest dimension of a DMA trasfer block is 16 bytes: how can I reduce it?  

Thanks and regards
Massimo Liggio