While trying to measure the speed of the outputs of a GPIO expander, some very short anomalies appear. In the example below, two of them last 4 ns each.
I can get rid of those anomalies by applying a glitch filter and setting the duration at eg. 8 ns.
- However, what are those glitches?
The critical question here is:
- Are they coming from the circuit I am analysing, or are they generated by the Saleae logic analyser hardware, firmware or software?
The first case may invite me to consider another IC. As the glitches are appearing randomly, using an oscilloscope to record a long time and spot the exact period when they appear may be difficult.
- What recommendation, if any, to prevent those glitches from appearing?
In an other configuration with channel 5 and 6 used for I2C, I have noticed the signal from channels 4 and 7 are more prone to raise glitches.
- Should shielded cables be used instead for the signals?
Configuration: Saleae 8 Pro, Logic 2.3.30 running on Debian