DLPS052 October 2015 DLPA3000
The SPI interface consists of several digital lines and the SPI supply. If routing of the interface lines is not done properly, communication errors can occur. It should be prevented that SPI lines can pickup noise and possible interfering sources should be kept away from the interface.
Pickup of noise can be prevented by ensuring that the SPI ground line is routed together with the digital lines as much as possible to the respective pins. The SPI interface should be connected by a separate own ground connection to the DGND of the DLPA3000 (Figure 32). This prevents ground noise between SPI ground references of DLPA3000 and DLPC due to the high current in the system.
Interfering sources should be kept away from the interface lines as much as possible. High-current lines, such as neighboring PWR_7, should especially be routed carefully. If PWR 7 is routed too close to SPI_CLK, for example, it could lead to false clock pulses and thus communication errors.