Fixed issue 31 PCA9685 configured to take i2c commands from all addre…

[ScottMonaghan]

…sses

Issue description:
I'm combining my PCA9685 with HT16K33 8x8 matrix.
As soon as I send a command to the HT1633 the PCA stops responding and all my connected servos go limp.

The solution for this issue was identified here: rwaldron/johnny-five#1591 (comment)

It appears the issue was fixed in the arduino library but not corrected in circuit python (see adafruit/Adafruit-PWM-Servo-Driver-Library@9f8e1dd#diff-5d1e3a5213c0ef6dedb2baf5cc323727L106-R110)

I confirmed the fix below works for me:
Change line 163 of adafruit_pca9685 in frequency(self, freq) from
self.mode1_reg = old_mode | 0xa1 # Mode 1, autoincrement on
to
self.mode1_reg = old_mode | 0xa0 # Mode 1, autoincrement on, fix to stop pca9685 from accepting commands at all addresses

I will submit a pull request with this change.

[kattni]

@ScottMonaghan Hello! Thank you for the contribution! The checks on this PR have failed. Please check out this guide to find out how to handle the formatting and Pylint checks. If you need assistance, please let us know. Tagging @FoamyGuy who can also assist you.

[ScottMonaghan]

@kattni and @FoamyGuy. I've updated my code to comply with pylint and Black. Also, I had to update one of the Adafruit-provided examples to comply with pylint (had to change import order of libraries).

Let me know if you need anything else!

[FoamyGuy]

@ScottMonaghan Thank you for submitting this! Also thanks for working through the CI checks, including the unrelated pylint error that popped up on you during the process.

I took a look through the the thread you linked. It does venture a bit deeper than my current understanding goes, but I do see the conclusion at the end and how you've applied the same fix here and it does make sense to me.

I do have one remaining minor question about the comment near this updated code: It specifies Mode 1. I am unsure of the context it's being used in though. If the change that we've made here results in using a different mode (in whatever context it's used) we should probably update the comment as well.

[ScottMonaghan]

@FoamyGuy I based the comment on @ladyada’s edit here which still calls out mode 1: adafruit/Adafruit-PWM-Servo-Driver-Library@9f8e1dd.

I assumed the original 0xA1 was a typo and 0xA0 was the correct mode 1 based on Lady Ada’s edit.

For confirmation you can refer to the PCA9685 data sheet.

[FoamyGuy]

I took a look through the data sheet and while I don't understand everything in there I do think I can understand enough to see that Mode 1 is referring to the register itself not really the value that is being set into the register.

This PR looks good to me now. But have not tested it, don't have this device.

[ScottMonaghan]

@FoamyGuy and @kattni Great! Is there anything else you need from me?

[kattni]

@ScottMonaghan Not at the moment! We should probably have someone else test this PR before merging, but that's to sort out on our end, not yours. It'll be a few days before I can do it. We'll figure it out though! Simply wanted to give you a heads up.

[ScottMonaghan]

@FoamyGuy and @kattni , I hope you both are well. I just wanted to follow up on this pull request.

I'm about to embark on a new open-source project with this library on the raspberry pi and it would be great if we can just pull down dependent libraries from pip without worrying about having to modify.

[kattni]

I'm ok with merging this. I haven't tested it, but I verified that the same change was made in the Arduino library. Thanks again for the submission, and thank you for your patience!

[kattni]

@ScottMonaghan This should be available on PyPI as soon as the release assets are deployed. It will be available in the Adafruit CircuitPython Library Bundle tomorrow.

[ScottMonaghan]

@kattni thank you! I'm honored to be able to contribute!