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TX and RX not working through the motor shield 2.3?
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TX and RX not working through the motor shield 2.3?

by mehtaboys on Fri Jul 26, 2019 10:22 pm

Hi. My son and I are newish to the Arduino. We are working on powering his lego power functions through the motor shield v2.3. We have everything working pretty well.

Yesterday we bought the HM-08 bluetooth module (link below) to allow us to use our iPad to communicate to the Arduino without the need for wires. The bluetooth connection works just fine when we just use the Arduino to connect to the module without the motor shield attached. However, once we add the motor shield (we used stacking headers so we can still use the pins) it will connect to the iPad but will not transmit or receive.

Does the motor shield have something in it that will interrupt or stop the TX/RX pins from working?

Here's a link to the bluetooth module. https://www.amazon.com/DSD-TECH-SH-HC-0 ... B01N4P7T0H

Any help would be awesome.

mehtaboys
 
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Re: TX and RX not working through the motor shield 2.3?

by franklin97355 on Sat Jul 27, 2019 1:24 am

Can you post a picture of your connections and the soldering from both sides of the board?

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Re: TX and RX not working through the motor shield 2.3?

by mehtaboys on Sat Jul 27, 2019 9:03 am

I attached images of the soldering from the headers. Also, we tested for continuity through each pin using a multimeter and each one worked.
Attachments
IMG_5747.jpeg
IMG_5747.jpeg (718.11 KiB) Viewed 124 times
IMG_3617.jpeg
IMG_3617.jpeg (536.82 KiB) Viewed 124 times
IMG_3243.jpeg
IMG_3243.jpeg (812.23 KiB) Viewed 124 times

mehtaboys
 
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Re: TX and RX not working through the motor shield 2.3?

by adafruit_support_bill on Sat Jul 27, 2019 9:08 am

Nice job on the soldering! Other than +5v and GND, the only other pins used by the shield are SDA and SCL. On an Arduino UNO, SDA is A4 and SCL is A5.
Which Arduino board are you using?
What pins are you connecting the bluetooth module to?

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Re: TX and RX not working through the motor shield 2.3?

by mehtaboys on Sat Jul 27, 2019 11:18 am

Thanks for the soldering encouragement!

We have the bluetooth module connected to an Elegoo Arduino Uno rev3.

Bluetooth > Arduino
VCC > 3.3v
GND > ground
TX > RX (pin 0)
RX > TX (pin 1)

I have also tried to reverse the data cables and it did not work either (RX>RX and TX>TX)

mehtaboys
 
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Re: TX and RX not working through the motor shield 2.3?

by mehtaboys on Sat Jul 27, 2019 11:52 am

I simplified everything to test it by following this video (https://www.youtube.com/watch?v=ELK5rwnUwgE).

We could get the light to light up using the app on my iPhone without the Motor Shield connected, but as soon as we added the motor shield, the bluetooth device would connect just fine on the phone, but not TX or RX.

Thinking it might be any shield, I tried it using an unused empty prototyping shield and it worked using that.

Do the TX and RX pins on the motor shield connect to anything or are just pass through? It does not look like it does connect to anything on the shield.

mehtaboys
 
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Joined: Fri Jul 26, 2019 10:13 pm

Re: TX and RX not working through the motor shield 2.3?

by adafruit_support_bill on Sat Jul 27, 2019 12:33 pm

There is no connection from those pins to any circuitry on the shield. It should be a straight pass-through via the stacking header pins.
https://cdn-learn.adafruit.com/assets/a ... 1396892649

It's a very clean soldering job with no bridging or other problems visible. To check if there is a short on the PCB itself, remove all connections from the shield and test the resistance between each of those two pins and the GND pin.

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Re: TX and RX not working through the motor shield 2.3?

by mehtaboys on Sat Jul 27, 2019 1:02 pm

I think I figured it out.

The stacking header pins coming from the adafruit into the Arduino board do not seem to connect inside the stacking header pins on the Arduino on Pin 0. I think it is a physical connection problem within the board's header jack. I am going to get another board and see if that fixes the issue. It is good to know that it is a straight passthrough for the connection.

I sure appreciate your super fast help with this. The best part about this has been to show my son how useful and helpful an online community can be.

If this does not fix it, I will update this post.

mehtaboys
 
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Joined: Fri Jul 26, 2019 10:13 pm

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