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Hi Forum; 

I went to use my CNC Router the other day and the cobbled together controller has give up.. Won't even boot after a few kicks and wiggles...

So I've put together a Raspberry Pi LinuxCNC controller with a mesa board to squeeze into the old PC location.

I've gotten  the Pi5/LinuxCNC all running off the boot image but just yesterday received and added the Mesa 7C81 I/O board. 

It's assembled and powers on, now I just need to figure how to connect the Mesa I/O to the outputs from LinuxCNC.   I guess it's time to read.

If anyone has a good 7C81 configuration page they can refer me to I'd appriciate it.  Ive just started and am not stuck yet but love a good example to follow. 

Adventure Awaits!

My second machine build log, If you want a good laugh and have time to waste that you will never get back
www.cnczone.com/forums/cnc-wood-router-p...t-log/35355-cnc.html
 

received support, it is working

Hi All,

have an early 7c81 with I bought couple years ago to use with the PI4, but that system was to slow for my setup.

Now I like to replace my rater large PC with a PI5 setup, but I found out that I have to flash it with a PI4 to make it work.
Can I flash the 7C81 with a PI3 instated?
I tried but it doesn't seem to connect, the wiring is correct and SPI is enabled.

do I have to use a certain version of Mesaflash, I have 3.5.11 from the LinuxCNC image.

 

Hi All, 
The ohmic enable gets randomly triggered when laser is enabled. The wiring is as follows to the 7c81 board: 5v from bob , signal to 7c81 encoder pin direct, pins 3 and 4 to gnd of bob. Please help!

hitchhiker wrote:

Warum brauch ich für die 7c81 ein usb-blaster?
Kann man nicht mit dem w5500 modul zugreifen und per mesaflash flashen per ethernet?
 

weil das ganze mesa zeugs nur mit der mesa gateware läuft, also auch das mesaflash,
du könntest noch rio darüber drauf flashen aber danach nicht mehr.
Flashen über Ethernet/SPI ist in rio nicht eingebaut.

@ bladekel:
i take look later

Warum brauch ich für die 7c81 ein usb-blaster?
Kann man nicht mit dem w5500 modul zugreifen und per mesaflash flashen per ethernet?

generell finde ich es pratischer die konfiguration am pc zu machen (VM mit Linux geht auch), dann könnte man auch den TangNano9k programmieren.

Für das ECP5 board brauch man den programmer (usb-blaster, der funktioniert auch am PI und die toolchan auch (arm64) )

Zum betrieb am RPI4 kann man SPI (Jumperwire kabel) nutzen oder en W5500 Ethernet-Adapter (~4-5Euro).

Dann musst du aber noch schauen was du ansteuern möchtest, also z.B. Stepper,
da wird es mit den dev-boards etwas umständlich.

Wie soll denn dein test-aufbau aussehen ?

Oder wenn du eine 7c81hast kannst du die auch nutzen, brauchst aber wie einen PC/VM + USB-Blaster zum programmieren.

Ahaaa i have laying a 7c81... i use on my rpi4 a 7i92.

Other question

What is the cheapest fpga with which i can start? Can you recommand...

Ach qas laber ich hier auf englisch...
Was ist deiner meinung nach der günstigste fpga zum starten?
Stm32 black und bluepill hab ich... auch n radpberry pico usw..

Danke dir

short version:

i put the ethernet cable in the rj45 socket

longer version:
i used the rio gateware and add an w5500 ethernet board to the spi pins:

 

Could you please explain how you connect the 7c81 via ethernet?

Hi All

Thanks for the help with this. But I am truly stuck up in calculation of the below.: 22900 and 23900 & 930000.0
 If the head is away I am getting a safe value of about 24000 for capacitive-sense-velocity in the halshow
My hm2_7c81.0.encoder.00.velocity-rpm is about 1440000 in the halshow.

When i run my program, the IHS happens perfectly but when the the THC takes control the torch just gets the down signal and never goes up. Kindly help with any formulas with these three parameters. Thanks!

# Configure a limit component for the capacitive sensor output since it is scaled
loadrt limit1
addf limit1.0 servo-thread
net capacitive-sense-velocity limit1.0.in
setp limit1.0.min 22900
setp limit1.0.max 23900
# hook up the limited signal to the plasmac arc voltage
net plasmac:arc-voltage-in <= limit1.0.out

and 

# Make a fake Ohmic probe based on the capacitive sensor
# Use the .velocity-rpm so the .velocity can be left unused for arc_ok
loadrt comp count=1
addf comp.0 servo-thread
net fake-ohmic-probe-in hm2_7c81.0.encoder.00.velocity-rpm comp.0.in0
setp comp.0.in1 930000.0
net plasmac:ohmic-probe comp.0.out
# ohmic output is comp.0.out



 

That looks OK but unless the low level signal is < 0.8V it cannot work.

That is, this is a hardware/interfacing issue.

The 7C81 inputs are fine with 5V signals but 1.8V is an indeterminate level
for the TTL level signals that the 7C81 expects

Do you have a data sheet for the encoder?


 

When I have time I will write up a "5aBOB for Dummies". My big router will use a 7c81 x 5aBOB.

Hi
Wiring looks ok to me. Please guide for the below points if they can help
a. Should I decrease the input voltage to 3 V. Will that help?
b. Should I decrease the output voltage of the encoder using a divider?
c. Perhaps changing the below values?
setp    hm2_7c81.0.encoder.00.counter-mode 1
setp    hm2_7c81.0.encoder.00.filter 0
setp    hm2_7c81.0.encoder.00.index-invert 0
setp    hm2_7c81.0.encoder.00.index-mask 0
setp    hm2_7c81.0.encoder.00.index-mask-invert 0

A 1.8V low level is not valid for a 5V single ended encoder output
Maximum low level for TTL signals is 0.8V

This may be a wiring error or similar.