Sometimes in MCU design, you may encounter serial communication issues in your UART, SPI, I2C, software-UART or etc. Often, these issues are related to accidental errors in design or implementation rather than bad chips. The following tips may help you to verify your issue.
Check whether your Clock Source is stable.
A clock source is one of the most important inputs for running an MCU. Any errors or instabilities in your clock frequency will affect the communications signals from that MCU. Selection of the right crystal, correct load circuit and proper board layout are important for a stable clock source too. Checking your clock signal performance can be one way to discover why your communication signals are malfunctioning.
Using the correct tools for measurement
A digital oscilloscope is an essential piece of equipment which can help to measure your communication signal and see whether it’s a good signal or not. It can help to detect any phase shifts or signal disturbances in an analogue waveform. A logic analyzer is used for verifying and debugging the operation of digital designs looking at logic states and timings. In some cases, a logic analyzer may not be sufficient to detect anomalies during the communication transmission. A logic analyzer might not see the glitches and drop, but a well set up scope will reveal all.