Pan tilt operating from script

Support
1

Hi there,

I have the pan-tilt hat for the raspberry pi.
I’ve built and installed it and confirmed it works, however it only works from the command line interactively and not from a script.

e.g. if I run:

python3
import pantilthat
pantilthat.pan(60)

The hat pans correctly, however if I have a script, panscript.py:

#!/usr/bin/python3
import pantilthat
pantilthat.pan(60)

that does the same and I run it

python3 panscript.py

the hat does nothing. weirdly the getpan and gettilt still return updated numbers as if the hat had moved.

Any help appreciated!

2

Well that’s curious. What happens if you put a small delay between import pantilthat and pantilthat.pan(60) like:

import time
import pantilthat
time.sleep(0.1)
pantilthat.pan(60)
3

ok, so some digging later.

If i give it an absolute value like

import pantilthat
pantilthat.pan(90)

it works even in the script, however if i use a variable in my script:

import pantilthat
panv = pantilthat.get_pan()
panv = panv - 10
pantilthat.pan(panv)

it does nothing (even if i add time.sleep(0.1)), yet it works interactively ie if i type

python3

then all the commands manually.
Any suggestions?

4

If you output your panv value in your script, what do you see?

Bear in mind get_pan() doesn’t get the position of the servos, but rather the last pan value sent to the controller so it can be a bit misleading.

5

I’ve added printing out the panv value:

import pantilthat
panv = pantilthat.get_pan()
panv = panv - 10
print("Panv: “, end=” ")
print(panv)
pantilthat.pan(panv)

and the script outputs a number that corresponds to the panv.

Its odd, but the script seems to be intermittently working. Sometimes if i issue it it now works, but won’t work if i run a second time just after. This is really making me scratch my head.

Given get_pan() returns the last position, i may have to keep a record of the position somewhere else to enable relative movements.