sam sokolik wrote: > the amps that I built had a boot strap that required charging.. I also > never had issues with it not charging at startup. I figured there was > enough dithering that everything 'just worked' tm > > The default state of my brush servo amps is to ground both sides of the motor. So, that charges the bootstrap capacitors.
The other feature of the IR2113 FET driver chip is the shutdown signal is latched. So, after shutdown, you have to pulse each transistor on for an instant to reset the shutdown latch. If you command movement in the plus direction, there may never be a PWM drive pulse in the minus direction to reset the latches for that chip, so it won't enable the low-side drivers on the opposite side. This lead to the motors sometimes acting "limp" when commanded to move, but would then suddenly recover and start holding position or moving. The fix was to give a short pulse in each direction to clear all the shutdown latches before trying to move. A state machine in the ppmc driver puts out one servo period of very short pulses in one direction, then the opposite direction the next servo period, so it is all taken care of in 3 milliseconds after coming out of E-stop. This happens well before you can hit the F2 key. I am going to have to implement this in a HAL component for a guy who wants to use my brush servo amps with a 5i20 he already has. It is not needed with my brushless amps that do it in the CPLD. Jon ------------------------------------------------------------------------------ Protect Your Site and Customers from Malware Attacks Learn about various malware tactics and how to avoid them. Understand malware threats, the impact they can have on your business, and how you can protect your company and customers by using code signing. http://p.sf.net/sfu/oracle-sfdevnl _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
