When browsing Dealextreme New Items one day I saw Logic Analyzer w/ DuPont Lines and USB Cable for SCM – Black product that was described as USBEE AX PRO. I had previously looked at the USBee but thought they were too expensive. This one was really cheap (around 10 Euros). I have not tried USBEE software before (but I have seen some good comments on it), so it is worth to try and compare how well it performs against Saleae Logic. The specifications of the product seemed to be pretty OK for a cheap logic analyzer: Max. sample rate: 24MHz @ 8 channels; Input voltage range: 0~5V; Low input voltage: < 0.8V; High input voltage: >1.4V. 24 MHz on the low side for a logic analyzer but is enough for debugging quite a lot of common protocols. Support protocol: SPI, IIC, UART, SMBus, I2S, CAN, Parallel, Custom, Search, Async, 1-Wite, PS/2.
The product came after some waiting. The package included just logic analyzer, USB cable and signal cabled (dupont line). The color of the device was black (in original product picture it was white). Interesting that the USB cable that came with the device was Nokia USB cable (KDE-2).
The package did not include any instructions or software. Then go to Internet and find the software. Google search headed me to USBEE download page. I downloaded USBEE AX PRO software and installed it. MiniLogic analyzer is detected. The applications with voltmeter just show some random voltage because the box I got does not have analogue input like (real USBEE AX PRO has analogue input). So this box is a clone that only supports the digital logic analyzer functions, and doesn’t have the analog circuitry (ADC) to read analog voltages. So this box is really is more like an USBEE ZX.
Some of the programs on the software suite worked well, some not entirely correctly and some not at all. Some of the USBEE AX software worked OK, some did not work as expected. For example in logic analyzer program the sample rate settings did not seem to affect anything. Output programs did not work at all. So did not anything that needed analog inputs (scope, multimeter etc..) Simple pulse counting program and frequency counter for example worked as expected.
Maybe I needed some other software that worked better. I saw that the USBEE download page has USBee Suite for DX, AX, ZX, SX and BusBee software. I tried it. The logic analyzer functions in that worked as expected when I set the software to 8 channel logic analyzer mode (turn off oscilloscope channel). I has some problems with 24 MHz sample rate (missing data), but with lower sample speeds everything worked as expected. The Windows tooling is pretty nice, it comes with built-in serial decoding.
To know sure what is inside the device I looked inside the box.
Yes. This device is a clone based on CY7C68013. It supports only digital logic analyzer functions. It does not support oscilloscope channels (no input pins for them). It does not seem to support signal output functionality (one feature I was looking when getting another logic analyzer). Considering all the hardware that goes into this product the sales price is cheap. If you try to buy CY7C68013 at small volumes, that IC itself costs more than the price of this whole product.
Other hardware details that I found out was that the device itself runs on 3.3V voltage (there is a linear regulator on the backside of circuit board that regulates USB around 5V to 3.3V). The inputs seems to be implemented with HC245 (if I read the code on IC right because it was in quite unreadable condition) between input pins and CY7C68013. There was 150 ohms series resistor from input pin to HC245, probably to provide some protection. There was also pull-up resistors for each pin (around 100 kohms to 3.3V) to keep the pins up when not connected anywhere. On strange thing: HC245 is a bidirectional bus buffer IC, so I wonder why did they not implement the output in this device because the hardware was already there!
Another thing I found out was that the USBee software license says that you may not use this Software in conjunction with any pod providing similar functionality made by other than CWAV. So using this box with the original software is against the license. So good that I bought this cheaper one and not the more expensive model. The reason why this kind of cheap clones seem to pop up is that the logic analyzer hardware on those is similar to CY7C68013 evaluation board, all that is needed to program the right USB ID into the board to make it being identified the device you want.
If this box can’t be used with original USBee software without breaking the license, then what can be done with it without breaking license rules (I quess many buyers will not bother looking at the license). Those cheap logic analyzer boxes seems to be commonly available, so maybe there are some other software to use with it. On the hardware side this USBEE AX clone seems to have a USBEE SX hardware inside (maybe just different firmware and USB ID).
Google search revealed some USBEE SX protocol details and Linux driver and experimentation framework for USBee SX (check readme). I am not sure if those are directly suitable with my “USBEE AX” box that is in features closer to SX than real AX.
It seems that sigrok project might be of help to have the software to run this device “legally”. The sigrok project aims at creating a portable, cross-platform, Free/Libre/Open-Source signal analysis software suite that supports various device types. sigrok developers have made an open-source firmware fx2lafw for Cypress FX2 chips which makes them usable as simple logic analyzer hardware. The interesting part is scriptable protocol decoding that is extendable with stackable protocol decoders written in Python 3. The Windows version of the software is still a work in progress. The developers don’t provide pre-built installers right now (and only command line tool fully supported). I will look this software again after some time when the Windows version gets easy to install or I have time to play with my old Linux box.
24 Comments
Tomi says:
This USBEE clone is only designed for TTL level signals.
In case you want to analyze RS-232 signals there is one simple hack to make it work.
Connect a suitable series resistor between RS-232 level signal and logic analyzer input. The resistor will attenuate the signal to levels that can be handled together with the protection diodes on the input buffer IC.
I found that 12 kohms resistors seemed to work OK for this.
No damage to protection diodes (worst case current less than 2 mA though protection diodes) and signal seems to get through nicely (I tested with only 9600 bps serial data but I think works for faster speeds also..)
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tubbutec says:
Thanks for this post. Your remark about the bidirectional driver gave me the idea to investigate a little further. As it turns out you can mod this LA pretty easily to provide output capabilities:
I have a little howto here:
http://tubbutec.de/blog/adding-output-capability-to-a-10e-logic-analyser/
tomi says:
Very nice follow-up on my article.
I have to try this output option!
Adding output capability to a 10€ logic analyser | tubbutec says:
[...] There is a nice writeup about which software you can use on the ePanorama Blog [...]
tomi says:
I successfully built the modification according your plans and documented my success at this blog article:
http://www.epanorama.net/blog/2013/01/14/adding-output-capability-to-a-10e-logic-analyser/
Debugging RS-232 with logic analyzer « Tomi Engdahl’s ePanorama blog says:
[...] are nowadays cheap logic analyzers (like Saleae Logic and USBEE) that can easily record many channels of fast changing digital signals and even decode the serial [...]
Purchasing Huf Sf says:
Evidently going through the article plenty will like it because it is accurate and it’s pleasant reading from an author that’s telling it on the net to think about
Tomi Engdahl says:
Comments at http://dx.com/p/logic-analyzer-w-dupont-lines-and-usb-cable-for-scm-black-148945 page say that this device might be better with some modifications:
“Pros: Great product for the price. Essentially unlimited samples. Arrived fast (2weeks).
Cons: Its claims on label and via USB ids to be AX Pro clone. Dont be confused – its not as its missing the analog functionality. Better to reflash the USB ids to Salae Logic one and use it as such. Best guide – http://club.dx.com/reviews/text/148945/375476 Also about triggering – it works ok if you only need level/edge triggering. If you need to trigger on some content in contious stream – its not possible.”
“With the Saleae software, this simply rocks. I haven’t installed the USBee software, but from what I read it’s a bit outdated.”
” this device uses a standard cypress chip, which is used also by other companies. Their software is thus compatible. There are also several blogs explaining how to make the device work (see e.g. jwandrews.co.uk). Works also on linux.”
Tomi Engdahl says:
Saleae Logic Analyser Clone Teardown and Reprogramming
http://www.jwandrews.co.uk/2011/12/saleae-logic-analyser-clone-teardown-and-reprogramming/
shed virginia says:
Hardly ever do I come across a site that’s both entertaining and educated, and let me let you know, you will have hit the nail on the head. Your concept is excellent; the issue is that not enough people are talking about it.
ivan says:
Can somebody provide the vid/pid of the USB Ax Pro?
tomi says:
Check the following web page: http://sigrok.org/wiki/Fx2lafw
Maruthi says:
useful information, thanks.
Please can you check I2C reading operation using this device?
tomi says:
This USBEE AX clone is an input only device.
You can’t use it as a master that control I2C bus (send requests etc..).
You should be able to use it to monitor I2C data generated by some other devices..
There is modification idea to add output to this device, take a look at
http://tubbutec.de/blog/adding-output-capability-to-a-10e-logic-analyser/
Maruthi says:
Ok,
I am not using LA as master to control I2C bus.
I monitored the I2C write operation using LA and it is working fine.
But when monitoring the I2C read operation using LA it is not working properly.
In normal I2C read first we send the slave address, ack, register address and then ack and start and read value.
when writing slave address, register address it is working properly.
but when reading value it is always showing 1. Is that due to pull up to keep the pins up when not connected anywhere.
Thanks.
Tomi Engdahl says:
CY7C68013A USB Board (mini)/EZ-USB FX2LP USB Module/Embedded 8051 Core Evaluation Development Board
http://dx.com/p/cy7c68013a-usb-board-mini-ez-usb-fx2lp-usb-module-embedded-8051-core-evaluation-development-board-295692#.Uwcm7oVM0il
Tomi Engdahl says:
It seems that due USBEE AX clones he original manufacturer seems to have changed things so that you have to pay for USBEE AX drivers to get then from the manufacturer. Check http://www.usbee.com/usbeeqxarinc429module-1-1.aspx
Maybe this is the answer to the clones… When there is a lot of cheap hardware clones, try to sell the software for this instead of your own expensive hardware…
Tomi Engdahl says:
My device looks same as in this page, so clould work with those drivers?
MCU123 USBee AX Pro clone
http://sigrok.org/wiki/MCU123_USBee_AX_Pro_clone
Tomi Engdahl says:
http://usbee-ax-test-pod.software.informer.com/download/
http://usbee-ax-pro.software.informer.com/
Tomi Engdahl says:
fx2lafw
http://sigrok.org/wiki/Fx2lafw
fx2lafw is an open-source firmware for Cypress FX2 chips which makes them usable as simple logic analyzer hardware.
USB2.0 Development Board : ITDB01
http://store.iteadstudio.com/index.php?main_page=product_info&cPath=1&products_id=51
Steve Cunningham says:
Excellent article thank you for the write up and the link from tubbutec
Tomi Engdahl says:
http://www.usbee.com/products.htm says:
The USBee Test Pods are a product invented in 1998 and was sold until the end of 2015. Due to very successful clones being developed that utilize our USBee software, we had to close the business.
Tomi Engdahl says:
[001] Sigrok and Logic Analyzers
https://www.youtube.com/watch?v=dobU-b0_L1I
Introduction and experiments with low-cost logic analysers and the sigrok software suite.