I'm building a pair of beam break timing gates using two sets of IR emitters and sensors placed about 100 feet apart. The idea is to start a timer when the first beam is broken and stop it when the second beam is interrupted. However, we're facing some challenges with the wireless communication needed for this setup. The connection can't rely on cables, and I'm aiming for accuracy within a hundredth of a second. I've tried using UDP, but I encountered a lot of packet loss, which made it unreliable. On the other hand, using TCP introduced noticeable latency, delaying the stop signal by several tenths of a second. I'm looking for suggestions on how to establish a reliable, low-latency connection between the two ESP32s. Is there a way to synchronize their internal clocks accurately to track the time elapsed? I know that commercial systems manage this well, but I'm unsure what techniques they use.
3 Answers
If you can manage to keep them connected with minimal interruptions, that should enhance reliability. Just remember to test different methods for sending stop signals; sometimes, tweaking the payload or transmission timing can yield better results as well.
For connecting two ESP32s, ESP-NOW is likely your best bet as it allows for low-latency communication directly between devices without WiFi. For accurate clock syncing, if you do need to use WiFi, remember that it introduces some delay. Adding GPS modules to both ESP32s might be the way to go for the tightest clock synchronization, which could help in achieving those precise timing results you need.
If both your ESP32s are connected to WiFi, consider using NTP (Network Time Protocol) servers to keep their clocks synchronized. When an event occurs, you can record the timestamps from each device and then have the second device send its timestamp back to the first. By comparing these synchronized timestamps, you should be able to get pretty accurate timing. With testing, you could achieve millisecond precision, but for better accuracy, think about adding GPS modules since they can provide microsecond-level precision.
I’m hoping to avoid needing an internet connection since these will be used in various locations with only a cellphone hotspot available. If I connect them briefly after powering on, can I maintain synchronization for a day with decent accuracy? I guess I'll have to test that out.