/iotsaResponseTime

Primary LanguageC++

iotsaResponseTime - web server to measure Stimulus-Response times

This is a wifi http server that allows triggering a digital signal, and measuring how long it takes for another digital signal to respond. It is built using the iotsa framework.

Home page is https://github.com/cwi-dis/iotsaResponseTime. This software is licensed under the MIT license by the CWI DIS group, http://www.dis.cwi.nl.

As distributed the service sends a 3.3v trigger signal on GPIO 4. This signal can be configured as "rise" (low to high transition), "fall" (high to low transition) or "toggle" (inverting the output). It then measures the time it takes until the expected response state change is detected on GPIO5. This expected response can be "rise", "fall", "same" (same transition as output) or "reverse" (reverse transition as output).

Configuration is done manually at /rtconfig or through the REST api at /api/rtconfig, which expects a JSON object with three fields:

  • "stimulus" one of the stimulus strings explained above,
  • "response" one of the response strings explained above,
  • "duration" duration in milliseconds after which the output is reset to the other state (mainly for rise or fall stimuli).

A stimulus is generated after a GET access to /api/stimulus. This call will fail for rise/fall stimuli for which the duration has not run out yet.

Response time is read with GET access to /api/response. If no response has been received yet this returns an empty object. If a response has been received the time difference between stimulus and response is returned in micros (in microseconds). Because this value is only recorded in 32 bits a less precise measurement (in milliseconds) is also returned, in millis.

Software requirements

Or you can build using PlatformIO.

Hardware requirements

  • a iotsa board. Alternatively you can use any other esp8266 board, but then you may have to adapt the GPIO pins used.