This blog is to introduce the logic analyzer and describe how it is an essential tool for embedded solution development. Meanwhile, I would cover several common brands of logic analyzers in the market and do a comparison of all of them.
Importance of Logic Analyzer for Embedded Solution Developer
Logic analyzers are used for digital measurements involving numerous signals or challenging trigger requirements.
A logic analyzer is an excellent tool for verifying and debugging digital designs. A logic analyzer verifies that the digital circuit is working and helps you troubleshoot problems that arise. The logic analyzer captures and displays many signals at once, and analyzes their timing relationships.
For me, when I use the Logic analyzer, it gives me the following features.
- Debug and verify digital system operation
- Trace and correlate many digital signals simultaneously
- Detect and analyze timing violations
- Trace embedded software execution
- Add the GPIO pin as the debugger and Trace the routine sequence
- Optimize the system performance, such as improve the refresh rate on the LCD display
- Measure the timing of the power up and system initialize sequence
Having an excellent logic analyzer is the mandatory tool for a professional embedded engineer.
I also found some URLs which provided very good overview on the logic analyzer.
Nordic Power Profiler Kit II (Cost US$93)
The Power Profiler Kit II is a standalone unit, which can measure and optionally supply currents all the way from sub-uA and as high as 1A on all Nordic DKs, in addition to external hardware.
The PPK2 can also use digital inputs as a low-end logic analyzer, enabling code-synchronized measurements. This can be achieved by connecting the digital inputs to an I/O pin on the external device under test (DUT). In order to use this functionality, the DUT must be powered by a VCC voltage of 1.6-5.5V. The digital input can then show what code is executed in the DUT at different points in time.
10x quicker sampling (i.e. 100ksps) compared with the long-term window of the previous generation enables maximum continuous resolution at all times. This enables a user to gather average acquisition data and zoom in for high-resolution data using the same window.
In the system block diagram of the PPK II, it has 8 bit bidirectional port as below.
To view the digital values, enable digital channels and zoom in on the main chart until the values are visible.
Saleae Logic Analyzer (8 ports ~ US $479)
Saleae is an American manufacturer of USB-powered electrical test equipment. The company sells digital mixed-signal logic analyzer, which combines a logic analyzer and oscilloscope.
It provides the excellent user interface and user friendly menu.
I used it before. But I think Saleae is overpriced. Also, the protocol is not much as expected particular on the serial protocol.
The Saleae Logic software includes the following protocol analyzers:
- Asynchronous Serial
- SPI (Serial Peripheral Interface)
- CAN (Controller Area Network)
- I2S Audio / PCM
- Manchester, Differential Manchester, Bi-Phase Space, and Bi-Phase Mark
- Synchronous Parallel
- PS2 Keyboard & Mouse
- Atmel SWI (Single Wire Interface)
- LIN (Local Interconnect Network)
- MDIO (Management Data Input/Output)
- USB Low Speed and Full Speed
- SMBus (includes PMBus and Smart Battery)
- HDLC (High-Level Data Link Control)
- Modbus RTU & ASCII
- HD44780 Parallel LCD
- SWD (ARM Serial Wire Debug)
Qingdao Kingst Electronics Co., Ltd. is a high-tech enterprise. They are engaging in developing and manufacturing innovative products in many fields, including the virtual instruments like logic analyzers and oscilloscope, kernel control module and MCU/embedded system training platform.
The price of the LA1010 (16 channels) is around US$50.
Protocol Support List
On the market, there are still multiple professional logic analyzers such as DSLogic, Zeroplus. But in this blog, I just would like to give the above 3 brands because I am still currently using them.
If you need to do the simple (no need to do the protocol decoder) task, it is highly advise to use the Nordic Power Profiler II. Because it can play as run-time current consumption multiple meter (maximum 1A).
If you need to choose the best price with performance, Kingst should be the best option. The lowest cost model LA1010 is around US$50. The LA5016 can do the QSPI decoding if you use it to drive the LCD display and it can also support the ISO7816 for secure element protocol. This is the reason why I use it most of time.
Welcome to give any welcome and suggestion.
I use the Nordic Power Profiler II and the Kingst LA2016. The PP2 is a great tool for taking current measurements, but I found the ‘logic analyzer’ to be too slow to capture rapid GPIO transitions sourced from the nRF52. That said, it is nice to have the same device be able to correlate GPIO transitions with current measurements when optimizing your software for minimum current draw.
The Kingst device seems like a very solid and affordable device. I’ve used it to debug I2C and SPI comms, and am yet to find any shortcomings.
I have used HP/Agilent LSAs in the past. For those who have access to such a device, good for you, I hope you use more than a small fraction of it’s capabilities. For the rest of us mere mortals, the current breed of sub $500 USB LSAs get the job done.