Serial connection not responding

I have an Arduino UNO and I can connect to it via IDE and flash it. I can connect to the serial console using serial monitor and/or putty. Everything seems to be in order and working fine. I can do $ or $$ and it returns data.

However, when I add the CNC Shield to the UNO it tries to connect to the console but I never gives me the grbl prompt and does not respond to key strokes.

If i try UGS it appears to connect to the UNO, but if i try to do a $ or $$ int he console there, it give an error of grbl not completely booted.

Could it be a bad CNC Shield? I am new to using Arduino and just was trying to get some direction on posible fixes.

Thanks

You are not giving us much useful information.

What PC operating system are you using?
What program have you got on your Arduino that gives rise to the comment "Everything seems to be in order and working fine"?

When you say "However, when I add the CNC Shield to the UNO it tries to connect to the console" what is it that "tries to connect"? And what "console" do you mean?

When you try with the CNC shield what program is on the Arduino?

...R

Sorry, like I said I am new to Arduino.

I have Windows 10 laptop
Putty v0.7
Arduino IDE 1.8.8

If I connect the plain Arduino UNO via USB to my computer. I can open Arduino IDE and load GRBL v0.8 on to the Arduino UNO. Once GRBL is loaded I can use the serial monitor in IDE or Putty and get the GRBL v0.8 prompt where I can actually type commands like $$ to see the GRBL settings.

Now I disconnect the UNO from my PC and add the CNC Shield board on top of the UNO board. I reconnect the USB cable and when I try to use the serial monitor in IDE or Putty, it never gets to the GRBL v0.8 prompt as it did without the CNC Shield installed.

So my question is why am I not getting to the GRBL v0.8 prompt with the CNC Shield installed on the UNO?

Power?

What shield is it, do you have the datasheet, a link of the product? Do you know what arduino pins the shield is using?

I have tried it with both power to the CNC Shield and without. No difference.

I have attached the CNC Shield Guide.

CNC Shield Guide - BM v1.0.pdf (923 KB)

Is anything connected to the RX/TX connections on the CNC shield?

Not sure I know what you mean. But I have tried it with just the CNC Shield installed with no motors or drivers (DRV8825) attached. I have tried it with the CNC Shield with a DRV8825 attached, I have tried it with the CNC Shield, a DRV8825 driver and a stepper motor attached. So basically it is like I cannot get a serial terminal prompt with anything attached to the UNO.

After a quick read of the PDF I can't see any reason why inserting the shield would prevent the normal functioning of the Arduino.

One stray thought is that the shield may be touching the USB connnector housing and causing a short circuit. That is easily checked by sliding a piece of paper between the housing and the shield.

Also check for inappropriate contact with any of the pins (I don't mean sockets) on the Uno.

...R

I checked and nothing seems to be touching anything it shouldn't. Actually, at the location of the USB connector there are no runs or solder connections at the spot.

One thing it am seeing it that if i just connect the UNO to the USB the 'on' led lights up and the 'L' led flashes a couple times and then the prompt appears on the serial monitor or putty.

But when i connect the CNC Shield to the UNO and plug into USB, the 'on' led lights up and the 'L' led stays on solid. Alos like when the CNC Shield is attached it is hanging and not completely bootng GRBL on the UNO.

gutntag:
But when i connect the CNC Shield to the UNO and plug into USB, the 'on' led lights up and the 'L' led stays on solid. Alos like when the CNC Shield is attached it is hanging and not completely bootng GRBL on the UNO.

Trying a different CNC shield is an obvious option, but perhaps rather expensive.

I think if this was my problem I would load the simple BLINK program onto the Uno and see if that works with the shield attached.

If it does NOT work then I would try using jumper leads to connect some of the Arduino pins to the shield to see if I could figure out exactly which connection causes the problem. I know that would be a tedious process.

...R

Thanks. I have tried the blink program. it works on the UNO by itself and doesn't with the shield attached. The LED stays on solid all the time with shield attached.

gutntag:
Thanks. I have tried the blink program. it works on the UNO by itself and doesn't with the shield attached. The LED stays on solid all the time with shield attached.

Then you are in for some tedious fault finding, or just trying another CNC shield.

...R

i have the same problem did you fix it?