Guide to Debugging a Slow Sketch
We've seen issues recently involving TAMProxy Sketch code running with long delay (hardware takes time to respond, and the delay gets longer and longer over time). This suggests that your communication queue between the NUC and the Teensy is backed up. Here are a few common reasons, and ways to debug them:
If you have a strange timing profile within your
loop() method, you may see issues with deriving from the
SyncedSketch class, as it tries to synchronize with the Teensy's loop while running
loop(). In this case, you may want to fall back to the normal
Sketch class, or fix your
loop() method (see below).
Hogging the NUC processor in your loop()
You might see issues if you are running processor-intensive code within your Sketch
- You might be running a really tight loop, like the loop below. This looks innocent but actually eats up a bunch of CPU cycles while doing nothing.
while timer.millis() < 2000: pass
Instead, you probably want to have your
loop()method give up control very quickly. Just do the check every loop and then return if it fails:
def loop(): if timer.millis() < 2000: return else: # Send some commands # Maybe set another timer # Don't take lots of processing time!
You also might not need to do your
loop()code every time you are given control. You can use a timer to only accept the loop every 10ms (as a suggestion):
def loop(): if global_timer.millis() > 10: # Do loop stuff global_timer.reset() else: return
- You might be doing heavy processing within
loop(), such as heavy-duty image processing. Instead you probably want to move this into another ROS node, and let it be managed as an entirely separate process.
Lots of communication with the Teensy
As you add more devices, you will inevitably just have more and more communication with the Teensy. If you are following the suggestions above and still have issues, you may want to edit
tamproxy/config.yaml and increase the
default_sleep_duration. This is the amount of time TAMProxy naturally sleeps the
loop() thread, to give the communication thread time to send packets to the Teensy.