Do you have diode protection across the coil to prevent a flyback
transient on your relay drive line?
On 3/9/2016 5:17 PM, [email protected] wrote:
I am working on a project where I have made modifications to the
beaglebone_pru_adc package available on GitHub here:
https://github.com/pgmmpk/beaglebone_pru_adc
<https://github.com/pgmmpk/beaglebone_pru_adc>
The code loads in firmware as a *.bin file to run on the pru. It is
complied PRU assembly from a *.p file.
My modifications were to implement a circular buffer in DDR based on
the oscilloscope_data() function in the module. This code grabs
samples from the adc like in the original code and stick the samples
in DDR, but it also updates memory pointers to wrap around. It loops
indefinitely and respects the cap_delay attribute.
The board is connected to provide fine grain analog data logging via
current transformer and voltage transformer on demand courtesy of the
PRU. For instance enabling RMS waveform calculation. I have also
written a python class that drives a latching relay. For test purposes
I hooked a heavy ~10A load to the relay. The PRU loop runs fine
indefinitely using the analog log to display RMS in the python code
space. However, the PRU loop continues running after the load is
switched on or off but the PRU continues looping only intermittently.
The load is resistive, yet clearly the interruption is correlated with
switching the load on or off. Sometimes the PRU continues running and
sometimes it stops running but only during a switching event.
I understand BeagleLogic.net may be a good lead to follow. In the
meantime, I watch for the PRU to stop loading new samples into the
DDR. Then I restart it. Very kludgy. My question is have you seen
anyone with similar problems switching heavy load and using the PRU?
Is there maybe an interrupt you think might be breaking the PRU out of
its loop? I can post code if it helps.
I really like these PRUs. Very slick to get real-time capabilities
plus the convenience of linux and speed of python prototyping.
Thanks,
Cressel Anderson
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