mesa 7i76E - new pinout?
04 Feb 2017 07:12 #87283
by Reinhard
mesa 7i76E - new pinout? was created by Reinhard
Hello,
after fiddling around a 7i80HD I'd like to go for a 7i76E - from the numbers of pins it should be fine, but the original pinout is too much wastage of pins. My stepper drivers have differential interface, so I don't need 5V and GND on the stepper channels. So I painted a new pinout.
Is it possible to achieve such a pinout with the 7i76E?
... and is there anybody willing to help me create a new bit-file?
I tried to download the xilinx ise, but I'm from outside of us and xilinx wants to verify my phone too
after fiddling around a 7i80HD I'd like to go for a 7i76E - from the numbers of pins it should be fine, but the original pinout is too much wastage of pins. My stepper drivers have differential interface, so I don't need 5V and GND on the stepper channels. So I painted a new pinout.
Is it possible to achieve such a pinout with the 7i76E?
... and is there anybody willing to help me create a new bit-file?
I tried to download the xilinx ise, but I'm from outside of us and xilinx wants to verify my phone too
![:( :(](/media/kunena/emoticons/sad.png)
Please Log in or Create an account to join the conversation.
- tommylight
-
- Away
- Moderator
-
Less
More
- Posts: 18515
- Thank you received: 6184
04 Feb 2017 07:40 #87285
by tommylight
Replied by tommylight on topic mesa 7i76E - new pinout?
You will have to wait for PCW to confirm, but i know for sure you can not change the +5V and GND pins on any board, Mesa or other.
Please Log in or Create an account to join the conversation.
04 Feb 2017 07:52 #87287
by Reinhard
Replied by Reinhard on topic mesa 7i76E - new pinout?
OK, thanks for the hint. Then I'll try another one.
Please Log in or Create an account to join the conversation.
- tommylight
-
- Away
- Moderator
-
Less
More
- Posts: 18515
- Thank you received: 6184
04 Feb 2017 08:07 #87288
by tommylight
Replied by tommylight on topic mesa 7i76E - new pinout?
You are welcomed.
Please Log in or Create an account to join the conversation.
04 Feb 2017 08:20 #87289
by Reinhard
Replied by Reinhard on topic mesa 7i76E - new pinout?
Please Log in or Create an account to join the conversation.
04 Feb 2017 14:13 - 04 Feb 2017 14:14 #87294
by PCW
Replied by PCW on topic mesa 7i76E - new pinout?
You cannot use bare FPGA pins for differential inputs (except LVDS which will not work with encoders)
Differential signals from encoders are used as a way of rejecting common mode noise, Standard RS-422 receivers
can detect as little as 200 mV of differential signal in as much as +-7V of common mode noise. The FPGA inputs in differential mode have a much smaller common mode range. Also Note the 7V of common more noise will destroy the FPGA chip in microseconds. It might be conceivable to use LVDS inputs with balanced resistive divider for each encoder input but not sure whether that's worth the effort.
Also in general its not suggested to drive step drives directly with the FPGA outputs. This can work if the FPGA is driving step drives with optocouplers with a common 5V (common Anode) connection and the FPGA is sinking current,
but is unlikely to work well for differential outputs since the outputs will not source current above 3.3V
If you want additional step/dir outputs and differential encoder inputs I would suggest adding 1 or 2 7I85S daughtercards
Differential signals from encoders are used as a way of rejecting common mode noise, Standard RS-422 receivers
can detect as little as 200 mV of differential signal in as much as +-7V of common mode noise. The FPGA inputs in differential mode have a much smaller common mode range. Also Note the 7V of common more noise will destroy the FPGA chip in microseconds. It might be conceivable to use LVDS inputs with balanced resistive divider for each encoder input but not sure whether that's worth the effort.
Also in general its not suggested to drive step drives directly with the FPGA outputs. This can work if the FPGA is driving step drives with optocouplers with a common 5V (common Anode) connection and the FPGA is sinking current,
but is unlikely to work well for differential outputs since the outputs will not source current above 3.3V
If you want additional step/dir outputs and differential encoder inputs I would suggest adding 1 or 2 7I85S daughtercards
Last edit: 04 Feb 2017 14:14 by PCW.
Please Log in or Create an account to join the conversation.
04 Feb 2017 14:54 #87295
by Reinhard
Replied by Reinhard on topic mesa 7i76E - new pinout?
Thank you very much for your attention!
_
Does it mean, that the step/dir pins from 7i76E have LVDS drivers?
My stepper drivers are Leadshine 3DM683 and LiChuan LCDA86H.
www.leadshine.com/UploadFile/Down/3DM683m.pdf
components-electronic-electrical.europag...el%20example)~3.html
_
May be 7i80HD was a better choice. The cncpod2 is something like 7i92 - so I already went for a bigger mesa card.
Are AM26C31/AM26LS32 from TI the right choice for protecting FPGA pins and support differential interfaces?
Can you help me create a bitfile for the mesacard of choice?
_
Ok, that sounds reasonable.You cannot use bare FPGA pins for differential inputs (except LVDS which will not work with encoders)
Differential signals from encoders are used as a way of rejecting common mode noise, Standard RS-422 receivers
can detect as little as 200 mV of differential signal in as much as +-7V of common mode noise.
Does it mean, that the step/dir pins from 7i76E have LVDS drivers?
My stepper drivers are Leadshine 3DM683 and LiChuan LCDA86H.
www.leadshine.com/UploadFile/Down/3DM683m.pdf
components-electronic-electrical.europag...el%20example)~3.html
_
I see - but that combination seems to expensive. The competitor is beamicon2 with cncpod2 for about 300 bucks (I'll have to create a daughterboard on my own). I'd prefer linuxcnc, but currently I don't see how I could solve my needs.If you want additional step/dir outputs and differential encoder inputs I would suggest adding 1 or 2 7I85S daughtercards
May be 7i80HD was a better choice. The cncpod2 is something like 7i92 - so I already went for a bigger mesa card.
Are AM26C31/AM26LS32 from TI the right choice for protecting FPGA pins and support differential interfaces?
Can you help me create a bitfile for the mesacard of choice?
Please Log in or Create an account to join the conversation.
04 Feb 2017 16:33 #87299
by PCW
Replied by PCW on topic mesa 7i76E - new pinout?
26LS32s are commonly used receivers for differential encoder signals and work well
26LS31s are not commonly used for differential drivers for step motor drives
because they dont have more than about a 3V output swing under load
As far as expense goes, I think you are somewhat comparing apples to oranges
The Benezan products you list do not AFAICT have multiple high speed encoder inputs
26LS31s are not commonly used for differential drivers for step motor drives
because they dont have more than about a 3V output swing under load
As far as expense goes, I think you are somewhat comparing apples to oranges
The Benezan products you list do not AFAICT have multiple high speed encoder inputs
Please Log in or Create an account to join the conversation.
04 Feb 2017 17:45 #87303
by andypugh
Replied by andypugh on topic mesa 7i76E - new pinout?
You seem to be wanting 6 steppers and 6 encoders (and ethernet?)
You can get that with a 7i80HD and 1 x 7i47. That comes to €262 from eusurplus. Less than the cncpod2. (and it could be €20 less with a 7i80HD-16 rather than -25, but they don't seem to list that option). You would probably want something like a 7i37TA for GPIO (that has 48V / 1A drivers). There are cheaper alternatives to the 7i37TA, but I suspect that the voltage/current flexibility is worth the extra.
If you are prepared to use the EPP parallel port as your communication, then you could use the 7i90 + 7i47 ($59 + $69 ) and add a 7i37TA ($79) for you GPIO, leaving one header free.
You can get that with a 7i80HD and 1 x 7i47. That comes to €262 from eusurplus. Less than the cncpod2. (and it could be €20 less with a 7i80HD-16 rather than -25, but they don't seem to list that option). You would probably want something like a 7i37TA for GPIO (that has 48V / 1A drivers). There are cheaper alternatives to the 7i37TA, but I suspect that the voltage/current flexibility is worth the extra.
If you are prepared to use the EPP parallel port as your communication, then you could use the 7i90 + 7i47 ($59 + $69 ) and add a 7i37TA ($79) for you GPIO, leaving one header free.
Please Log in or Create an account to join the conversation.
05 Feb 2017 05:04 #87330
by Reinhard
But anyway - may be I was wrong respect to the encoders. I wanted to have an upgrade path for small servos, but after a quick research it looks like leadshine offers the same interface for small servos as for CL steppers. So may be, I don't need the encoder channels.
_
I have about 3-4m from Stepper-Drivers to Screen and if I place the PC next to the Stepper drivers, I need long cables for screen, keyboard, mouse, whatever ...
If I place the PC next to Screen, I only need an Ethernet-cable from PC to Controller, which will be next to the Stepper drivers.
Regarding my requirements, I'll start with 5 CL steppers, a spindle channel, 6 endstops, 4 relais and 3 MPG channels and several IOs for pushbuttons ...
My upgrade path is 2 additional stepper channels and 3 endstops.
So if I can drive 7 steppers at reasonable price, I would prefer that instead of switching stepper channel.
And yes, if there's a good reason, I'll keep on thinking about oranges and don't care for apples.
Replied by Reinhard on topic mesa 7i76E - new pinout?
You're right! With Benezan I have only one choice, so with linuxcnc I already thought about oranges instead of apples and was willing to pay more (benezan price includes software license).As far as expense goes, I think you are somewhat comparing apples to oranges
But anyway - may be I was wrong respect to the encoders. I wanted to have an upgrade path for small servos, but after a quick research it looks like leadshine offers the same interface for small servos as for CL steppers. So may be, I don't need the encoder channels.
_
Yes, ethernet is fixed for the following reason:... (and ethernet?)
I have about 3-4m from Stepper-Drivers to Screen and if I place the PC next to the Stepper drivers, I need long cables for screen, keyboard, mouse, whatever ...
If I place the PC next to Screen, I only need an Ethernet-cable from PC to Controller, which will be next to the Stepper drivers.
Regarding my requirements, I'll start with 5 CL steppers, a spindle channel, 6 endstops, 4 relais and 3 MPG channels and several IOs for pushbuttons ...
My upgrade path is 2 additional stepper channels and 3 endstops.
So if I can drive 7 steppers at reasonable price, I would prefer that instead of switching stepper channel.
And yes, if there's a good reason, I'll keep on thinking about oranges and don't care for apples.
Please Log in or Create an account to join the conversation.
Time to create page: 0.164 seconds