RGB LCD Shield & serial question

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pww
 
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RGB LCD Shield & serial question

Post by pww »

I just assembled and tested one of these shields... I noticed that after uploading the example sketch, the LCD works, but the USB serial connection to the host computer drops off-line. The only way I can reconnect is if I disconnect the USB cable, then remove the shield, then connect the USB cable again, and upload a blank sketch to prevent the previous program from auto-running and dropping the serial connection to the IDE.

Q: I'm assuming this is due to the sharing of the I2C and serial interface on the Uno?
Q: (Unrelated) Is there a way to stop the boot loader from auto-running what was previously uploaded? (Or should I hardwire a toggle switch and have my setup() check the switch position and continue executing or exit, depending on the switch position?)

thanks

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adafruit_support_bill
 
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Re: RGB LCD Shield & serial question

Post by adafruit_support_bill »

Q1 - There should be no interference between I2C and the serial communication. They use different pins. If you post clear photos of the front & back of the shield we can look for any assembly issues that might affect serial communication.

Q2 - Not without hacking the bootloader. Embedded systems are generally designed to come up running with no user intervention.

JD3
 
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Re: RGB LCD Shield & serial question

Post by JD3 »

Not quite clear on your setup.

The backpack is wired to your Arduino w/ serial wires.

You are also connecting the backpack with an USB cable.

Is this correct?
Last edited by JD3 on Wed Oct 10, 2012 4:49 pm, edited 1 time in total.

pww
 
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Re: RGB LCD Shield & serial question

Post by pww »

(sorry, don't have access to a camera or the Uno right now. They're at home)

The shield sits correctly on the Uno. It's not a mechanical or electrical issue. Like I said, once the example runs, the USB connection to my host computer drops. The example program runs correctly. Pushing the shield's reset button re-registers the USB connection for a few seconds and then the Uno's program runs and the connection drops.

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adafruit_support_bill
 
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Re: RGB LCD Shield & serial question

Post by adafruit_support_bill »

How are you powering this? USB only? I'm wondering if the added current to light the backlight may be causing enough of a dip in power to reset the connection.

JD3
 
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Re: RGB LCD Shield & serial question

Post by JD3 »

....
Last edited by JD3 on Wed Oct 10, 2012 4:53 pm, edited 1 time in total.

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adafruit_support_bill
 
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Re: RGB LCD Shield & serial question

Post by adafruit_support_bill »

@JD3 - The OP is using the RGB/LCD Shield - not the serial backpack. The Shield communicates via I2C.

pww
 
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Re: RGB LCD Shield & serial question

Post by pww »

Powered using the USB connection. I have the battery case thing that came with the starter kit. I can use this in parallel with the USB connection? It won't back feed into the USB?

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adafruit_support_bill
 
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Re: RGB LCD Shield & serial question

Post by adafruit_support_bill »

It's worth a try. The power will not feed back into the USB.

pww
 
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Re: RGB LCD Shield & serial question

Post by pww »

OK. The external power supply didn't change anything.

Upon closer examination, it turns out that the header pins for the LCD panel actually extends far enough through the LCD shield, that when the shield is installed firmly on the UNO, the pins touch 3 pins on the ICSP 6 pin header block.

So when the pins don't touch, everything works fine. I guess I should follow the last step instructions to clip those pesky leads. Doh!

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Re: RGB LCD Shield & serial question

Post by adafruit_support_bill »

That would do it! Thanks for the follow-up.

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