Debugging I2C, SPI, and RS-232 with the Serial Protocol Analyzer Functions of the Hantek LA5034 Logic Analyzer

The Hantek LA5034 Logic Analyzer allows the technician or Engineer the ability to debug and troubleshoot serial bit streams encountered in I2C, SPI, and RS-232 serial data busses. Logic Analyzers without the ability to decode the data stream make it extremely difficult and error prone to manually decode these types of serial busses. This would consist of the engineer capturing the data stream on the logic analyzer then manually writing down the corresponding 1’s and 0’s. He would then convert these binary bits into the hexadecimal equivalent value.

We will describe the simplicity of using the protocol to view the data stream from an RS-232 signal. I used a breakout box to access the RS-232 signals from a PC used to control a programmable power supply. Since the RS-232 standard only requires a minimum of two wires (Tx and Rx), we will connect these two signals to the Logic Analyzer channels A0 and A1. We could have used any two pins for this connection since we will define the signals in the Bus setup screen. We need to open the Bus Setup screen by clicking SETUP then Bus Setup or by choosing Bus Setup from the toolbar. Now add two buses that each only have one signal. We can name these new buses Rx and Tx respectively. Next open up the Plug In Manager and select the RS-232 setup screen. Click Analyzer then Plug-In Manager then select RS-232 and click the EDIT button. Now fill in the parameters for Baud rate, Stop bits, Parity and Flow Control. You will also need to type in the name of the signal that was setup when we created the two new buses (Tx and Rx). You will have to select either the sending (Tx) or receiving (Rx) signal to decode since only one can be decoded at any time. When you click OK , the decoded RS-232 signal should show up at the bottom of the screen.

The setup for the other supported serial buses is equally easy and allows the user to debug and troubleshoot both I2C and SPI buses in real-time.


George Leger has a Masters in Electrical Engineering from Stanford University, worked in private industry pioneering surface-mount technology and in government research labs for twenty years, published several papers on surface-mount technology, co-authored papers published in national symposiums on accelerator technology, was past president of SMTA and an adjunct professor at the community college level, holds a patent, and is a certified microchip design partner, serving as a consultant to many companies developing electronic circuits.

Leave a Reply