Struggling with communication protocols like SPI, I2C, CAN or serial? You're not alone. Whether you're working with high-level environments with HAL or Arduino, or diving deep with CMSIS, debugging is often necessary because things rarely work perfectly from the start.
The challenges can be daunting at low levels and even more complex for those operating at higher levels. Understanding what's actually happening can feel elusive.
For instance, consider SPI where setting the slave select pin to low is crucial for sending communication to the device. It's easy to mistakenly power the pin instead, preventing data from reaching its intended destination without any clear indication of what went wrong. This leaves us meticulously combing through code, trying to piece together where a misstep might have occurred and how everything should ideally function.
We need a tool that can cut through the complexity of abstract settings and directly reveal the tangible outcomes of our program. Enter the oscilloscope, seemingly tailor-made for this task. Available in 2 and 4-channel models with integrated logic analyzers, these devices promise effective performance. However, their usefulness is tempered by limitations in frequency and channels, alongside a price tag that may deter newcomers and hobbyists.
Yet, consider this: oscilloscopes excel in measuring analog phenomena, whereas our focus lies in discrete communication protocols. Unlike scrutinizing minute voltage changes, our priority is simply detecting the presence or absence of current flow. Thus, the precision of an oscilloscope is unnecessary, especially for debugging binary signals. Rather than investing approximately 500 euros in an oscilloscope, a more practical solution emerges—a multi-channel logic analyzer costing about 10 euros offers comparable functionality at a fraction of the price.
I write this because it was a revelation to me. Faced with numerous signal programming challenges on my Nucleo board and CMSIS, I was on the verge of purchasing an oscilloscope. This isn't a promotion for any specific product, so I won't be providing any links. To discover such a tool, simply search for "logic analyzer" on any search engine.
A logic analyzer is designed to capture and analyze digital signals within an electronic circuit. It can record and display multiple digital signals concurrently, making it invaluable for debugging and validating digital systems.
Most of these analyzers are multi-channel devices equipped with probe cables and powered via USB for connection to your computer. Software is essential for interpreting the captured data. I found Logic 2 particularly accessible and used it to great effect. Connecting a functioning SPI to all four channels yielded compelling results.
By linking CS, MISO, MOSI, and CLK to the analyzer, I quickly generated voltage graphs. The software features an analysis tool where you can configure your communication parameters. It allows you to view received and transmitted data in binary, hexadecimal, decimal, and ASCII formats. Moreover, it provides timing information, calculates frequencies and duty cycles, and can measure pulse-width modulation.
In summary, these tools are indispensable for identifying and resolving issues within complex digital systems, ensuring designs operate as intended. I trust this information proves helpful to you. Thank you for taking the time to read it.
