Pi-Blaster Raspberry PI3+ Bullseye : brushless motors do not run

[peniblou]

Bonjour Pi-Blaster team.

I have a Raspberry PI 3+. It was running perfectly with ServoBlaster and Stretch.

I had to install Bullseye, and took advantage of this new environment to install Pi-Blaster (replacing Servo-Blaster). Installation was easy and successful. However, I cannot make it work...

ESC is waiting for a signal between 1 ms and 2 ms. I did :
pi@raspberrypi: /pi-blaster$ echo "4=0.1" > /dev/pi-blaster (expecting a 1ms signal)
pi@raspberrypi: /pi-blaster$ echo "4=0.11" > /dev/pi-blaster (expecting a 1.1 ms signal)
But no noise , nothing ...

After few (multiple ) tries I did :
pi@raspberrypi: /pi-blaster$ echo "4=0.01" > /dev/pi-blaster and
pi@raspberrypi: /pi-blaster$ echo "4=0.011" > /dev/pi-blaster
The brushless motor then works very badly : forward and backward every seconds. No other values are working 0.012 0.009...
Remark: I though it was a problem of frequency ( ESC is waiting for 20ms signal = 50hz when Pi-Blaster mentions 100 Hz) but
the problem 120 issued by Whiskthecat specifies that we have a 50 Hz signal ...)

So my questions are:
- Is my environment Raspberry PI 3+ / Bullseye compatible with Pi-Blaster ?
- Did I do something wrong ? Can you confirm that my first command ( value =0.1 and 0.11 ) should work ?
- If you do not see any possible fix, can I just use Servo Blaster (and uninstall Pi-Blaster) ?

Many thanks for your help and support

Michel Hirvois

[sarfata]

Hi Michel,

The rpi 3+ should work well.

Are you able to hook an oscilloscope to the raspberry pi to see what is actually generated?

Can you copy/paste the text information displayed by pi-blaster when you start it?

If you do not see any possible fix, can I just use Servo Blaster (and uninstall Pi-Blaster) ?

Yes of course. I am not sure I understand why that would not be an option.

[peniblou]

Bonjour Thomas,

Thanks for coming back to me.
Unfortunately, I do not have an oscilloscope to check the signal generated by the pi.

I have done some additional testing. To ease things, I will ask 2 questions

• Q1- expected parameters for an ESC motor brushless
  I need a 50hz signal. The pulse signal should vary from 1ms to 2ms .. See figure below.
  What parameters do you recommend ?
  

-Q2- I am not sure of the procedure to change the parameters ...
This is what I do
o I edit the pi-blaster.c file and change the parameters cycle_time_us ( 2000) and sample_us (100)...
o make pi-blaster
pi@raspberrypi:/pi-blaster $ make pi-blaster
gcc -Wall -pedantic -std=c99 -o pi-blaster pi-blaster.o mailbox.o_
o Check new parameters
pi@raspberrypi:/pi-blaster $ ./pi-blaster
MBox Board Revision: 0xa52082
DMA Channels Info: 0x7ff5, using DMA Channel: 14
Using hardware: PWM
Number of channels: 32
PWM frequency: 50 Hz
PWM steps: 20
Maximum period (100 %): 2000us
Minimum period (5.000%): 100us
DMA Base: 0x3f007000
pi-blaster: Failed to open /dev/mem: Permission denied
pi-blaster stopped.

I am not sure that my changes are taken into account. ( I am not an expert in C and compilation... ) Even if I delete the files pi-blaster.c et pi-blaster , pi-blaster still works ! (badly). For information, my pi-blaster starts automatically at boot.

Many thanks in advance for your help

Michel Hirvois

[peniblou]

Bonjour ,

I have installed ServoBlaster with still some issue that I have added in

Therefore I close this current issue #128