Data acquisition and control is the key issue for embedded applications. With the expansion of the precision and the promotion of the conversion speed used in the digital to analog devices, we need more efficient computing platforms and methods. The PCM1702 is a precision 20bit digitaltoanalog converter. It also features a very low noise, ultralow distortion and fast settling current output. SPI bus interface is the typical application of embedded Linux system. In this paper, SPI bus driver is achieved through the general purpose I/O pins based on DSP and ARM dual core processor on highperformance DaVinci OMAPL138 platform, which is applied in highprecision DA chip PCM1702. The experimental results show that the method is efficient and stable, which is aimed at the high processing capacity of precision components.