[TriEmbed] Raspi, Python and PWM

Rodney Radford ncgadgetry at gmail.com
Thu Sep 10 08:16:03 CDT 2015


Why deal with a kernel module at all if you can solve the problem from user
land, and get the benefit of up to 22 servos at the same time?

On Thu, Sep 10, 2015 at 8:28 AM, Geoffrey Tattersfield via TriEmbed <
triembed at triembed.org> wrote:

> As far as completing the adafruit lesson, you have to deviate from how it
> is currently written to complete it.
>
> In the following forum post, adafruit support acknowledged that the kernel
> module no longer exists and the lesson is on the list to be
> updated. wiringpi is prescribed. compiling/loading the old kernel module is
> proscribed. :)  See page 2.
>
>
> https://forums.adafruit.com/viewtopic.php?f=10&t=49300&hilit=servo+raspberry+pi+lesson+8
>
> On Wed, Sep 9, 2015 at 10:14 PM, Ted Pudlik via TriEmbed <
> triembed at triembed.org> wrote:
>
>> I have controlled the hardware PWM from Python using wiringpi2.  Here
>> <https://github.com/tpudlik/Birdfeeder/blob/master/iron_curtain.py> is
>> an example.  I found this discussion
>> <http://raspberrypi.stackexchange.com/questions/4906/control-hardware-pwm-frequency>
>> useful in figuring out how to control the frequency.
>>
>> Best,
>> Ted
>>
>> On Wed, Sep 9, 2015 at 9:21 PM, Rodney Radford via TriEmbed <
>> triembed at triembed.org> wrote:
>>
>>> I use servo blaster for generating pwms on the Raspberry pi.
>>>
>>> It sets up a linked list dma structure to automatically generate pwm
>>> signals with no cpu intervention and can control over 20 servos with easy
>>> control from python, C and via the command line.
>>>
>>> There is a kernel driver and user daemon. I prefer the daemon as it is
>>> not kernel version dependent.
>>> On Sep 9, 2015 9:08 PM, "John Rock via TriEmbed" <triembed at triembed.org>
>>> wrote:
>>>
>>>> I’ve been working through the Adafruit tutorials for the Raspi.
>>>>
>>>>
>>>>
>>>> Tutorial #8 is about driving a servo off the Raspi PWM pin #18.
>>>>
>>>>
>>>>
>>>> I have supposedly installed the Occidentalis extensions to Raspian,
>>>> which looked like it completed successfully.
>>>>
>>>>
>>>>
>>>> I am not able to access the folder structure in the code in the
>>>> tutorial.
>>>>
>>>>
>>>>
>>>> Anyone out there a Python / Linux / PWM expert that has been able to
>>>> control a servo from the Raspi PWM pin #18?
>>>>
>>>>
>>>>
>>>> John Rock
>>>>
>>>>
>>>>
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>>
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>
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