Programming error only when shield is connected

I have made my own shield for solar charging and can only program the Mega 2560 when the shield is disconnected. I do not have anything connected to pins D0 and D1. Pins 0 and 1 are the one used for programming, correct? I tried three different Mega's. I get errors during upload, like "com port busy".

Hi, can you post a circuit diagram of your project, so that we can see what you have connected and if possible a picture of your shield. Tom... :)

I have made my own shield for solar charging and can only program the Mega 2560 when the shield is disconnected. I do not have anything connected to pins D0 and D1. Pins 0 and 1 are the one used for programming, correct? I tried three different Mega's. I get errors during upload, like "com port busy".

Pins 0 and 1 are the one used for programming, correct?

Yes.

I get errors during upload, like "com port busy".

Maybe you should post something like your schematic. No, wait. Not something like your schematic. Post your exact schematic and the EXACT error messages.

Crossposting won’t get you more answers. In fact, it pisses a lot of people off that might have answers.

AtlantaRobotics: I get errors during upload, like "com port busy".

That suggests the problem is to do with the virtual COM port on the PC. Either the USB interface is not working correctly, or something else on the host PC is accessing the COM port. The error message seems to imply the latter. It would help if you posted the exact error message you got. Can we assume that the only thing you're doing between the working and non-working case is removing the shield? Does the shield make any connection to the reset pin?

Sorry, here is the error message.

avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: ser_send(): write error: sorry no info avail

The schematic of the mega is attached. It shows pin 0 is attached to an encoder knob bu I disconnected it while I am troubleshooting. The code is also attached.

Solar Oven Shield 0v3b.pdf (98.2 KB)

Solar_Oven_0v3b.ino (63.6 KB)

You're wasting everybody's time by asking the same question in multiple places. The problem is already being discussed here:

http://forum.arduino.cc/index.php?topic=191706.msg1416382

Topics merged. Cross-posting wastes time DO NOT CROSS-POST

Sorry about cross posting. I posted the first one and it disappeared from where I posted it and I could not find it so I posted another one figuring I did not submit it.

I do not have anything connected to the reset pin or pins 0 and 1. I have tried this on 3 different PCs. It only happens when my shield is connected during programming. I have also tried several Mega 2560s.

So I am guessing no one has any other thoughts or ideas as to why this is happening?

So I am guessing no one has any other thoughts or ideas as to why this is happening?

You say that there is nothing connected to pins 0 and 1, but your pdf pf the schematic says that there IS something attached. Whatever it is that is attached (to D18, D19, and D0) is unlabeled.

I mentioned earlier that though the schematics show something connected to pin 0 I have actually disconnected it in order to troubleshoot this problem. You mentioned D18 and D19. Are these used for programming? I thought only D0 and D1 were used for programming

I got it working. I was the power supply. When programming and powering from the USB the voltage was 4.9V and it programmed fine. With the shield connected the voltage was 4.85V and it would not program when power was supplied via the USB. I put 12V on Vin and the voltage showed 5.01V. With 12 volts on Vin the Arduino Mega was able to be programmed over USB. I also reconnected D0 and still programs fine. I do not understand why such a little voltage difference caused this but it did.

I had something similiar to your problem. The way I ended up fixing it was easy.... I just unplugged the usb cord waited a min and then plugged it back in. Now I am able to send my programs without error. Try this. It could happen to be this simple for you too. :D