PWM is "pulse width modulation". PDM is "pulse density modulation".
In PWM you have a carrier frequency, a duty cycle, and a resolution. The duty cycle specifies what fraction of the cycle should be high, or active. The resolution determines how accurately the requested duty cycle can be implementes in the pwm output signal. For example, if the PWM signal ha sonly 2 bits of resolution, your effective duty cycle can only take the values 0%, 25%, 50%, or 75%. In PDM you have a "time-slot duration" (or time-slot frequency) and a duty cycle. You do not have a carrier wave (like you do with PWM). Instead each little "time slot" in the output signal is independently set high or low, and they average to the requested duty cycle. Regarding your second question, the hm2 firmwares are compiled with the free-as-in-beer VHDL tools from Xilinx. Jeff Epler recently did some work to automate this process, but I don't know much about it. -- Sebastian Kuzminsky never be discouraged just let your nerdy flourish -----Original Message----- From: claude <men...@bluewin.ch> Subj: [Emc-users] hostmot2 PWM Date: Tue 2010 Feb 16 13:13 Size: 1K To: emc-users@lists.sourceforge.net Hi all, First, I take this opportunity to say a big THANKS to every one for this wonderful piece of software. I use it for machining and also some automatic machine with great reliability and flexibility. I may use for a future project some MESA card with hostmot2 "firmware". After reading a bit how to set PWM, I don't get the complete picture, what is PDM PWM ? what is the difference between this and "regular" PWM ? is there somewhere drawing on how it work (I look a bit on VHDL code, but it pretty difficult to get the exact way of work). As a second point, I may do some change to the PWM VDHL code. I didn't find any explanation on how to compile FPGA (I have knowledge on FPGA and VHDL language, unfortunately only on Altera one). As much as I imagine, there should be some free way to do compilation and test, but this doesn't seems to be integrated with EMC distribution, can someone give me some hint ?? regards Claude ------------------------------------------------------------------------------ SOLARIS 10 is the OS for Data Centers - provides features such as DTrace, Predictive Self Healing and Award Winning ZFS. Get Solaris 10 NOW http://p.sf.net/sfu/solaris-dev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ SOLARIS 10 is the OS for Data Centers - provides features such as DTrace, Predictive Self Healing and Award Winning ZFS. Get Solaris 10 NOW http://p.sf.net/sfu/solaris-dev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
