MESA 7i76e PWM Pin needed on Expansion Connector

Dear all,

For a scientific project on our university we are using Linuxcnc for controlling a 3D-printer. However, to complete our work we would need a single PWM Pin on the 7i76e to control UV-LEDs. At the moment we are already using 5 stepgens and several I/O pins on the board.

I ve found out, that its possilbe to get a PWM Pin by using a custom bitfile. Are there already custom bitfiles out there which we could use - or do we need to write our own?

Greetings,
Michael

Hi tommylight,

thank you for the fast response. According the datasheet of my led driver there is a PWM frequency range from 100 Hz to 1 Khz.

I think i still would prefer the pins on the expansion header since they re 5V which already suits to the driver.

Ah okay sure. Can you tell me how I can use PWM on the normal outputs? in the PNPconf I can not choose a PWMgen.

The 7i76e_7i76x1_5abobD.bit config has a PWMGen on pin 1 of expansion connector P1 and
7i76e_7i76x1_5abobpD.bit has 3 PWMGens on P1 pins 1,3,5 (DB25 pins 1,2,3)

Note that if you use the expansion pins directly, its best to use a series resistor of
say 220 Ohms to prevent negative inputs from damaging the input clamp diodes.

It works! I flashed the new firmware with the PWM Pin 1 on P1 and I could add an PWMgen in hal.

Thank you for your help!

Hi Xpertmill
I am very interested b y PWM on expansion ports of 7i76e, do you have any description of what you did?
Which firmware did you load? where did you get it?
Regards

Firmware for the 7I76E is available from Mesa in the 7i76e.zip file:

www.mesanet.com/software/parallel/7i76e.zip

If you don't need all 5 stepgens, its probably more convenient to use
7i76e_7i76x1pD.bit which replaces the fifth stepgen with a PWMgen.
so you have a buffered 5V signal.

Hi PCW! Thank you so much for this quick answer.
Yes I need 5 stepgens.
Sorry I am rather new in linuxcnc world, I still have a lot to learn.
I thought that there are many different firmware for 7i76e depending on which resource we want to use on this board. Am I right? If yes, can you please tell me where can I read about different versions?