Using Cheap Logic Analyzer with PulseView

In my fourth semester of engineering I built a logic analyser mostly using analog components and parallel port. After that I had not thought about one. But for last few weeks I have been dabbling with reverse engineering some signals. A logic analyser comes in handy for that. I really wanted to buy a 8 channel Saleae Logic 8, but it’s not available in India and I forgot to get one last time I was in USA. So I settled for a Saleae Compatible, very affordable, Chinese made logic analyser. It doesn’t have a name. Just says “Logic Analyzer, 24 Mhz, 8CH”, somewhere on the vendors site says Saleae compatible. I was going to use Sigrok/PulseView on my Ubuntu anyway. So the only question was if this hardware is supported by Sigrok. Since Sigrok supports lots of Saleae compatible devices. I was sure this one would work.

It's a no name device, as big as match box. Here connected to test D7 of NodeMCU (ESP8266).

It’s a no name device, as big as match box. Here connected to test D7 of NodeMCU (ESP8266).

Installing Sigrock/PulseView was straight forward. Install the sigrock package for Ubuntu1. It will install everything required.

$sudo apt-get install sigrock
$pulseview

Once you install, connect the logic analyzer to USB port. start the pulseview by running the command pulseview. In the UI, go to File – Connect to Device. On the screen select driver as fx2lafw and scan devices. Your device should appear. If not just unplug and plug-in again and scan. It should appear. Mine appears as Saleae device. Select the device.

Selecting Logic Analyser Device

Selecting Logic Analyser Device

To test I wrote a simple program to give me a pulse of 10ms HIGH and 20ms LOW signals.

void setup() {
  pinMode(13, OUTPUT);
}

void loop() {
  digitalWrite(13, HIGH);
  delay(10);            
  digitalWrite(13, LOW);
  delay(20);  
}

I uploaded the code to NodeMCU and connected D7/pin-13 of NodeMCU to CH1 Logic Analyzer and ground on NodeMCU to ground on Logic Analyzer. Once I powered up the NodeMCU and started the logic Analyzer. Magic, signal appeared on the screen. At 20KHz (lowest capturing rate)

At 20 KHz

At 20 KHz

At 24MHz (Highest capturing rate), I had to capture a lot of samples as the signal is too big (or slow?).

At 24MHz

At 24MHz

Looks like everything is working well as of now. But these are just preliminary tests. I really want to use built in protocol decoders. I will use it with one of them and update you with the details.

Also if you are in USA and visiting India soon. Let me know. I really want that Saleae Logic Analyzer.

  1. Ubuntu installs PulseView 0.2 version. So I downloaded Linux AppImage binaries and using it now. It’s version 0.5, looks so much better and supports lots of protocols.

You may also like...

1 Response

  1. August 6, 2018

    […] Analyzer is a good tool to have on your work bench. You read about my experiments with cheap knockoff last time. Now I have a Zeroplus LAP Educator1. It’s a 8 channel Logic Analyzer targeted at […]

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.