In a previous article, we introduced a logic analyzer built using a serial port. Today, we will discuss a logic analyzer based on USB2.0+FPGA.
Before we begin, let’s introduce a logic analyzer’s host software – sigrok. Without good host software, even if the hardware is built, the experience will not be good.
sigrok
Here is the official website:
https://sigrok.org/wiki/Main_Page
sigrok is an unavoidable host software for logic analyzers. You can see the currently supported logic analyzers:
This is clearly a product modified from sigrok or directly using it, and there are many products based on sigrok that have not published their source code.
Currently supported interfaces:
-
Cypress FX2 (CY7C68013 series) -
FTDI FT245 USB FIFO (FT232 series) -
RS232 -
Ethernet -
USB Interface Microcontroller -
JTAG – suitable for similar to ChipScope -
PCIe -
Parallel Port -
Cypress FX3
The last three are also supported, but currently, there are fewer open-source hardware solutions.
The development documentation related to sigrok is also very rich, and you can download it from the official website for research. Next, we will introduce two logic analyzers based on USB2.0+FPGA.
FX2+FPGA
FX2 is relatively inexpensive and is also the architecture recommended by sigrok.
On this website, there are four logic analyzers based on this architecture:
https://sigrok.org/wiki/Fx2grok
You can choose according to your interests.
FT232+FPGA
This architecture can use either FT232 or FT2232, and it employs the FT245 USB FIFO+FPGA architecture.
The recommended project for this architecture is:
https://github.com/perehinik/Logic_Analyzer_PCB
The architecture is XC7A15T+FT232, which is very cost-effective. The internal logic of the FPGA is as follows:
Of course, this project does not use the sigrok host software but has developed its own host software based on PYTHON. However, the difficulty of porting is not high, providing an additional choice.
Conclusion
sigrok is at the core, constructing the entire open-source world of logic analyzers. However, sigrok supports not only logic analyzers but also the following devices:
The significance of research is quite substantial.
The last two logic analyzer projects are also worth replicating. If you only want to create a usable logic analyzer without focusing on FPGA, it is still recommended to use the RP2040 and its upgraded version of the logic analyzer (24 channels, 100Msps logic analyzer), which costs less than 20 and offers an experience worth over 100.
https://github.com/gusmanb/logicanalyzer
