Google Git
Sign in
android/platform/external/walt/refs/heads/android11-mainline-tethering-release
commit
d215878a4cc9c769ad0d1ad4f153ec1970c817b3
[log]
author
Tai Kuo <[email protected]>
Thu Jul 30 18:36:24 2020 +0000
committer
Automerger Merge Worker <[email protected]>
Thu Jul 30 18:36:24 2020 +0000
tree
00e0f9517f22f9f9fc95aa6a242a072f9b188f09
parent
4c763195c12454b17be4ffa74e30c90a36e4a9ca [diff]
parent
26b4ade211075ab524c99a8d4e68c8593b7d8457 [diff]
pywalt: fix stuck communication am: de48cf557f am: 842e8b8860 am: 26b4ade211

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/walt/+/12239743

Change-Id: Icadf1cf1a5a4e0f09a8ee7e63976d1035749b3bb
tree: 00e0f9517f22f9f9fc95aa6a242a072f9b188f09
  1. android/
  2. arduino/
  3. docs/
  4. hardware/
  5. ios/
  6. pywalt/
  7. server/
  8. AUTHORS
  9. CONTRIBUTING.md
  10. CONTRIBUTORS
  11. LICENSE
  12. METADATA
  13. MODULE_LICENSE_APACHE2
  14. OWNERS
  15. README.google
  16. README.md
README.md

WALT Latency Timer

DISCLAIMER: This is not an official Google product.

WALT is designed to measure the latency of physical sensors and outputs on phones and computers. It can currently perform the following measurements:

  • Tap latency - time from the moment a finger-like probe touches down (or up) on the screen until the kernel timestamps an ACTION_DOWN (or ACTION_UP) event. This physical contact with the screen is timed using an accelerometer mounted on the probe.
  • Drag latency (scroll).
  • Screen draw latency - using a photodiode that detects whether the screen is black or white.
  • Audio output and microphone latencies.
  • MIDI input and output latencies

The WALT app for Android can be installed from Google Play or downloaded in the releases section; the iOS app must be built from source.

WALT photo

Notes

  • Hardware build instructions can be found in this repository under hardware/.
  • Clock synchronization details are described here.
  • The Android/iOS device and Teensy clocks have a tendency to diverge due to differing clock frequencies. This means they will go out of sync after several minutes. The workaround is to use the app to re-sync the clocks. Some, but not all tests in the app will sync the clocks when starting a measurement.
  • Python code used to communicate with WALT from Linux and ChromeOS can be found here.