Raspberry Pi 4 with Mesa 7c81
16 Jan 2024 02:50 #290824
by PCW
Replied by PCW on topic Raspberry Pi 4 with Mesa 7c81
Typically you would use a breakout board like the common "5 Axis Mach" BOB
and not connect directly to the 7C81s ports
and not connect directly to the 7C81s ports
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16 Jan 2024 11:24 #290856
by andypugh
Though admittedly that doesn't really answer your questions, because the functions of the various chips depends on the firmware flashed to the 7c81.
There are a number of possible firmwares, but it is probable that the one you have is good enough for your purposes.
There are two ways to identify which signals are on each header pin of the 7C81. You can use mesaflash, or you can run a LinuxCNC HAL command line session.
Starting with the HAL method, this will also check that LinuxCNC comms to the board are working.
Open a terminal.
If all it well, this should connect to the Mesa board, and give you a list of what function is on which IO pin.
You can then continue with additional HAL commands, for example
When finished:
The other way is with mesaflash. You might need to install this: "sudo apt-get install mesaflash"
(This might need to tbe "sudo mesaflash")
Report back what the results are, there are a number of possible hurdles to either of these working immediately.
Replied by andypugh on topic Raspberry Pi 4 with Mesa 7c81
Have you found the 7C81 manual? www.mesanet.com/pdf/parallel/7c81man.pdfThe current gap I’m trying to fill is how to get from the Mesa 7c81 board to the 5 StepperOnline DM542Ts (Spindle, X, Z, A, & C). In particular, I am at a loss on how to get the 3 needed signals to the DM542Ts: Step, Direction, & Enable.
I am seeking some guidance on where to find instructions or manuals which can me help get started. I recognize that this is probably a very basic set of questions, so I appreciate whatever help can be provided to point me in the right direction.
Though admittedly that doesn't really answer your questions, because the functions of the various chips depends on the firmware flashed to the 7c81.
There are a number of possible firmwares, but it is probable that the one you have is good enough for your purposes.
There are two ways to identify which signals are on each header pin of the 7C81. You can use mesaflash, or you can run a LinuxCNC HAL command line session.
Starting with the HAL method, this will also check that LinuxCNC comms to the board are working.
Open a terminal.
halrun
loadrt hostmot2
loadrt hm2_rpspiIf all it well, this should connect to the Mesa board, and give you a list of what function is on which IO pin.
You can then continue with additional HAL commands, for example
show pinWhen finished:
exitThe other way is with mesaflash. You might need to install this: "sudo apt-get install mesaflash"
mesaflash --spi --device 7c81 --readhmid(This might need to tbe "sudo mesaflash")
Report back what the results are, there are a number of possible hurdles to either of these working immediately.
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16 Jan 2024 14:38 #290873
by PCW
Replied by PCW on topic Raspberry Pi 4 with Mesa 7c81
The default 7C81 firmware is 5ABOBx3 which is compatible
with the common Mach 5 Axis BOBs
with the common Mach 5 Axis BOBs
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16 Jan 2024 14:55 #290874
by andypugh
It looks like you will have to use the manual to map the physical pin numbers to IO numbers to find where each signal is, which is slightly unfortunate.
Replied by andypugh on topic Raspberry Pi 4 with Mesa 7c81
IO Connections for P1+Serial
Pin# I/O Pri. func Sec. func Chan Pin func Pin Dir
0 0 IOPort PWM 0 PWM (Out)
0 1 IOPort None
0 2 IOPort StepGen 0 Step/Table1 (Out)
0 3 IOPort None
0 4 IOPort StepGen 0 Dir/Table2 (Out)
0 5 IOPort None
0 6 IOPort StepGen 1 Step/Table1 (Out)
0 7 IOPort None
0 8 IOPort StepGen 1 Dir/Table2 (Out)
0 9 IOPort StepGen 2 Step/Table1 (Out)
0 10 IOPort StepGen 2 Dir/Table2 (Out)
0 11 IOPort StepGen 3 Step/Table1 (Out)
0 12 IOPort StepGen 3 Dir/Table2 (Out)
0 13 IOPort None
0 14 IOPort QCount 0 Quad-A (In)
0 15 IOPort QCount 0 Quad-B (In)
0 16 IOPort QCount 0 Quad-IDX (In)
0 17 IOPort None
0 18 IOPort None
IO Connections for P2+Serial
Pin# I/O Pri. func Sec. func Chan Pin func Pin Dir
0 19 IOPort PWM 1 PWM (Out)
0 20 IOPort None
0 21 IOPort StepGen 4 Step/Table1 (Out)
0 22 IOPort None
0 23 IOPort StepGen 4 Dir/Table2 (Out)
0 24 IOPort None
0 25 IOPort StepGen 5 Step/Table1 (Out)
0 26 IOPort None
0 27 IOPort StepGen 5 Dir/Table2 (Out)
0 28 IOPort StepGen 6 Step/Table1 (Out)
0 29 IOPort StepGen 6 Dir/Table2 (Out)
0 30 IOPort StepGen 7 Step/Table1 (Out)
0 31 IOPort StepGen 7 Dir/Table2 (Out)
0 32 IOPort None
0 33 IOPort QCount 1 Quad-A (In)
0 34 IOPort QCount 1 Quad-B (In)
0 35 IOPort QCount 1 Quad-IDX (In)
0 36 IOPort None
0 37 IOPort None
IO Connections for P7+Serial
Pin# I/O Pri. func Sec. func Chan Pin func Pin Dir
0 38 IOPort PWM 2 PWM (Out)
0 39 IOPort None
0 40 IOPort StepGen 8 Step/Table1 (Out)
0 41 IOPort None
0 42 IOPort StepGen 8 Dir/Table2 (Out)
0 43 IOPort None
0 44 IOPort StepGen 9 Step/Table1 (Out)
0 45 IOPort None
0 46 IOPort StepGen 9 Dir/Table2 (Out)
0 47 IOPort StepGen 10 Step/Table1 (Out)
0 48 IOPort StepGen 10 Dir/Table2 (Out)
0 49 IOPort StepGen 11 Step/Table1 (Out)
0 50 IOPort StepGen 11 Dir/Table2 (Out)
0 51 IOPort None
0 52 IOPort QCount 2 Quad-A (In)
0 53 IOPort QCount 2 Quad-B (In)
0 54 IOPort QCount 2 Quad-IDX (In)
0 55 IOPort None
0 56 IOPort None It looks like you will have to use the manual to map the physical pin numbers to IO numbers to find where each signal is, which is slightly unfortunate.
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16 Jan 2024 15:19 - 16 Jan 2024 16:05 #290876
by PCW
Replied by PCW on topic Raspberry Pi 4 with Mesa 7c81
Is that the latest mesaflash?
(current mesaflash should print the 7C81 pinouts correctly)
(current mesaflash should print the 7C81 pinouts correctly)
Last edit: 16 Jan 2024 16:05 by PCW.
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- richcolvin
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29 Feb 2024 21:20 #294802
by richcolvin
Replied by richcolvin on topic Raspberry Pi 4 with Mesa 7c81
I have received the two Sain Smart 5-Axis CNC Break Out Boards (ST-V3) which connected easily to the Mesa 7C81.
When I connect these BOBs to the StepperOnline DM542T drivers, it seems that the common connection is +5V, not GND. Does it seem right that it would be connected this way?
BOB DM542T
+5V PULse +
ENAble +
DIRection +
ENable ENAble -
DIRection DIRection -
STEP PULse -
When I connect these BOBs to the StepperOnline DM542T drivers, it seems that the common connection is +5V, not GND. Does it seem right that it would be connected this way?
BOB DM542T
+5V PULse +
ENAble +
DIRection +
ENable ENAble -
DIRection DIRection -
STEP PULse -
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29 Feb 2024 21:22 #294803
by richcolvin
Replied by richcolvin on topic Raspberry Pi 4 with Mesa 7c81
Regarding the Sain Smart 5-Axis CNC Break Out Boards (ST-V3) and lathe spindle, is the A axis used for the spindle? Or is that somehow configured in LinuxCNC?
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29 Feb 2024 21:43 #294804
by PCW
Replied by PCW on topic Raspberry Pi 4 with Mesa 7c81
1, You can wire the drives with either
common ground:
= drive step-/dir- --> GND, BOB step/dir --> drive step+,dir+
or common +5V:
= drive step+,dir+ --> 5V, BOB step/dir --> drive step-,dir-
If you use common 5V, you must invert the step outputs
as they are now active low
Typically you would not use an axis for the spindle
common ground:
= drive step-/dir- --> GND, BOB step/dir --> drive step+,dir+
or common +5V:
= drive step+,dir+ --> 5V, BOB step/dir --> drive step-,dir-
If you use common 5V, you must invert the step outputs
as they are now active low
Typically you would not use an axis for the spindle
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