PCB Anti-Interference Design for High Speed DSP System
Generally, PCB high speed DSP system is designed according to the system's specific requirements. However, due to limited design capabilities and laboratory conditions, if anti-interference measures are not reliable and stable, then DSP program flow will be disordered when work environment is not ideal or there exists electromagnetic interference. When the DSP normal working code can not be restored, flight program or crash or even components damage will happen. Therefore, EPCB suggests that you should pay attention to take appropriate anti-interference measures.
PCB anti-interference design for hardware
Hardware has high efficiency when dealing with anti-interference. Thus, if allowed by the system complexity, cost and size, then PCB anti-interference design for hardware is preferred. Common hardware anti-interference technology can be summarized as follows:
a.Hardware filtering: RC filter can greatly weaken all kinds of high frequency interference signal, such as it can suppress the "burs" interference.
b.Reasonable grounding: A reasonable design of the grounding system for high-speed digital and analog circuitry with low impedance and large area of the ground layer is very important. The grounding layer can provide a low-impedance return path for high-frequency currents, while also minimizing EMI and RFI and shielding external disturbances.
c.Shielding measures: AC power, high frequency power, strong electrical equipment, arcing spark, all will produce electromagnetic waves, and become a source of electromagnetic interference noise, the metal shell can be used to surround the device together, and then grounded,
which is an effective shielding measure for electromagnetic interference.
Optical isolators can effectively avoid interference between different circuit boards. High-speed optical isolators are commonly used in interfaces for DSP and other devices (such as sensors, switches, etc.).
PCB anti-interference design for software
PCB anti-interference design for software has irreplaceable advantages compared to hardware. In the DSP application system, you should fully tap the anti-interference potential ability of the software, so as to suppress the impact of interference to a minimum. Common software anti-interference technology can be summarized as follows:
a.Digital filtering: The noise of the analog input signal can be eliminated by digital filtering. Commonly used digital filtering techniques are: median filter, arithmetic mean filter, etc.
b.Trap setting: Set a boot program in the unused program area, jump to this area when the program is interfered. The boot program will be forced to capture the program to the specified address, where a special program is designed for error handling.
c.Redundant instruction: Inserting two or three bytes of no-op instruction NOP after a double-byte instruction and a three-byte instruction.