MESA PWM
13 Feb 2014 23:05 #43828
by kostas
How?
That said, Its probably possible to make a bitfile with inverted PWM output with some minor VHDL hacking
How?
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13 Feb 2014 23:19 - 13 Feb 2014 23:20 #43830
by PCW
Last edit: 13 Feb 2014 23:20 by PCW. Reason: formatting
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14 Feb 2014 02:44 #43834
by eslavko
Use hardware watchdog!!!
At startup ALL driver enable should be dissabled. When LinuxCNC starts then use F1 estop latch to kick watchdog on hardware pin. So in meantime you should set other pins correctly. Kep this as safery feature. When you plug in machine nothing should happen! Even when PC is booted up. (if you use just parport then there is mess of signals in bootup process) NOTHING SHOULD HAPPEN UNTIL YOU PRES F1 AND/OR EXTERNAL POWERON BUTTON.
This cost one extra releay and few diodes to make chargepump. It cost nothing compared to fingers!
At startup ALL driver enable should be dissabled. When LinuxCNC starts then use F1 estop latch to kick watchdog on hardware pin. So in meantime you should set other pins correctly. Kep this as safery feature. When you plug in machine nothing should happen! Even when PC is booted up. (if you use just parport then there is mess of signals in bootup process) NOTHING SHOULD HAPPEN UNTIL YOU PRES F1 AND/OR EXTERNAL POWERON BUTTON.
This cost one extra releay and few diodes to make chargepump. It cost nothing compared to fingers!
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14 Feb 2014 03:54 #43835
by kostas
This works as advertised. Thanks Peter!
Eslavko, that's why I'm worried of this small pulse at the beggining.
I probably should have an enable pin in my hardware somewhere but for the work I'm doing now it does not really matter and there are no safety issues.
This is a very small machine, actually a toy of mine. Anyway, this should work ok now.
Eslavko, that's why I'm worried of this small pulse at the beggining.
I probably should have an enable pin in my hardware somewhere but for the work I'm doing now it does not really matter and there are no safety issues.
This is a very small machine, actually a toy of mine. Anyway, this should work ok now.
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14 Feb 2014 04:24 #43836
by eslavko
Even toy machine can drill trought a finger...
At least wire E-Stop properly. Don't rely on F1/ESC. The LinuxCnc window can lost focus and keyboard will not respond.
This is a very small machine, actually a toy of mine. Anyway, this should work ok now.
Even toy machine can drill trought a finger...
At least wire E-Stop properly. Don't rely on F1/ESC. The LinuxCnc window can lost focus and keyboard will not respond.
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20 Jul 2014 09:14 #48960
by PCW
The PWM rate is settable to a few Hz up to ClockHigh/512
Clock high is either 100 MHz or 200 Mhz depending on FPGA card
This makes the maximum PWMrate ~192 KHz or ~384 KHz depending on FPGA card
The PWM rate is a global setting however so if you have multiple devices using the PWM,
they all have to use the same frequency. The PDM rate setting is separate however so if you
need different rates, and some devices can use PDM (7I48 and 7I33 can for example) this allows
an independent PWM rate to be set
Clock high is either 100 MHz or 200 Mhz depending on FPGA card
This makes the maximum PWMrate ~192 KHz or ~384 KHz depending on FPGA card
The PWM rate is a global setting however so if you have multiple devices using the PWM,
they all have to use the same frequency. The PDM rate setting is separate however so if you
need different rates, and some devices can use PDM (7I48 and 7I33 can for example) this allows
an independent PWM rate to be set
The following user(s) said Thank You: vre
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