AK-ST7MC

milantrcka · ‎2007-03-09

Posted on March 09, 2007 at 23:09

AK-ST7MC

milantrcka · ‎2011-05-17

Posted on May 17, 2011 at 10:13

I have 3-phase BLDC motor, ~100W, up to 27000rpm at 30VDC bus; AK-ST7FMC Control Panel software ver 2.1; sensor or sensorless mode on Softec eval board: communications between software control panel and inDART-STX crash when PWM exceeds approx 80% or during an ''aggressive'' start or transient. Problem seems to be associated with high-power, high-speed operation. Error message says ''communications lost... read manual''. No mention (that I can find) of conditions under which this should be happening. Either the processor crashes or the comm crashes - not sure what. Do not see too much noise on 5V power (processor or inDART, power does not sag. RF noise is present from the power stage.

Any suggestions how to troubleshoot the problem would be greatly appreciated

Milan

gaetano · ‎2011-05-17

Posted on May 17, 2011 at 10:13

Hi Milan,

I suggest you to use a shielded USB cable with ferrite cores present on each cable end.

Then, you should also check if, during communication fault, there is a signal RESET in the MCU (please, check it with a scope). In most cases this is the reason for receiveing the error message you're reporting.

If it is confirmed, you should investigate for understanding the origin of this MCU reset: for instance, a spike (duration 1 us) in the Vcc voltage could be enough to trigger off an internal reset (as the Low Voltage Detector LVD is on).

Regards,

Tanio

milantrcka · ‎2011-05-17

Posted on May 17, 2011 at 10:13

Tanio,

thank you for your suggestions - did all that you suggested but still had lost communications events. The processor was indeed resetting (as indicated by blinking red-green lights). Adding 3x 1uF ceramic and 360uF electrolytic caps to motor bus and 2x 2uF to the processor finally fixed it.

Thanks again for pointing me in the right direction.

Cheers

milan