SE254
The SE254 is a 4-channel logic analyzer sampling at up to 250 MS/s. It is the entry point to the range, aimed at education and at benches where four channels are enough.
Principle of operation​
The SE254 stores captured samples in a 256 Mb embedded memory and transfers them to the computer when the capture ends. It does not stream while capturing. This keeps the device simple and low cost, but it means capture length is limited by the internal memory, and not by how long you are willing to wait as it is on the SP259 and SP1000G.
Pre-trigger samples come from a ring buffer, so the device is always holding recent history and can supply it when the trigger fires.
Specifications​
| Channels | 4 |
| Maximum sample rate | 250 MS/s |
| Logic bandwidth | 50 MHz |
| Embedded memory | 256 Mb |
| Streaming while capturing | no |
| Input impedance | 200 kΩ, 8 pF |
| Threshold groups | one, covering all four channels |
| Logic levels in ScanaStudio V6 | 1.8 V, 2.5 V, 3.3 V, 5 V |
| Absolute maximum input | ±25 V |
| External trigger in / out | no |
| Pattern generator | no |
The full timing and DC characteristics are in the SE254 datasheet.
The SE254's architecture makes 250 MS/s best suited to intermittent traffic such as I2C or SPI. For a signal that toggles continuously above 10 MHz, use 125 MS/s, which is correct in every case up to the 50 MHz logic bandwidth.
Connections​
The logic probes use a standard 2.54 mm 5-pin connector: four channels and a ground. You can use your own wire harness instead of the supplied probes, in which case keep the wires under about 25 mm for signal integrity.
Connect the ground lead. A noisy capture is usually caused by a bad ground connection, not by the device.
What is in the box​
- The SE254
- A 5-lead hook probe set, colour-coded to match the channel colours in ScanaStudio
- A 1 m micro-USB 2.0 cable
Drivers​
None, on any platform. The SE254 enumerates as a standard USB serial port, which Windows, macOS and Linux all support natively, so there is nothing to install and no administrator rights needed.
On Linux, the udev rule shipped with ScanaStudio is still required for the software to open the port. See Installing ScanaStudio.
Using it​
The SE254 has no external trigger connectors and no outputs, so the External trigger tab and the Pattern Generator card do not appear. Everything else in this manual applies: Configuring the device for the acquisition settings and Trigger for the conditions it can wait for.