Simple "Blink" sketch does not survive reboot with SM5100B Cell Shield in place

Projects Networking, Protocols, and Devices
1

Hello,

I am working may way through my first major arduino project.

I have a SM5100 cellular shield mounted on top of my Arduino Uno. I can use the pass-thru sample sketch and make phone calls, send text messages, etc.

What seems odd though, is if I upload a simple "blink" sketch to the board the sketch will run. However, once I unplug power for more then 2 seconds and plug it back in (either USB or external power applied to 5V+ and GND) the LED blinks the rapid 3 pulse continuously from the bootloader rather then the designated sketch. This continues until I either remove the SM5100B Cell shield or re-upload the sketch.

/*
  Blink
  Turns on an LED on for one second, then off for one second, repeatedly.
 
  This example code is in the public domain.
 */

void setup() {                
  // initialize the digital pin as an output.
  // Pin 13 has an LED connected on most Arduino boards:
  pinMode(13, OUTPUT);     
}

void loop() {
  digitalWrite(13, HIGH);   // set the LED on
  delay(1000);              // wait for a second
  digitalWrite(13, LOW);    // set the LED off
  delay(1000);              // wait for a second
}

I was reading on the FAQ that the bootloader expecting might be expecting serial input... and not loading the designated sketch.

What am I missing?

Thanks for your help.

  • Ben
2

I have a SM5100 cellular shield mounted on top of my Arduino Uno.

Is this shield connected to pins 0 and 1? If so, and it generates any noise on those pins during a reset, the bootloader could be fooled into thinking that a sketch is coming.

3

PaulS:

I have a SM5100 cellular shield mounted on top of my Arduino Uno.

Is this shield connected to pins 0 and 1? If so, and it generates any noise on those pins during a reset, the bootloader could be fooled into thinking that a sketch is coming.

Yeah... it does connect to 0 and 1. Guess I should experiment jumper wiring it the Arduino instead of using using stackable headers.

Thanks for the suggestion... I'll look into it.

  • Ben
4

On a hunch I went down to my local Radio Shack and bought another Arduino Uno (new one is a rev 3, old one is not labeled... so guessing rev 1).

This one does not exhibit the same symptom. So far, all the reboot and power disconnection attempts i've thrown it at have still permitted the sketch to start properly.

I guess I goofed up the bootloader somehow.

Neither of these are the SMD variety... any issue swapping chips (between rev 1 and rev 3 board) to further troubleshoot?

Thanks.

  • Ben
5

any issue swapping chips (between rev 1 and rev 3 board) to further troubleshoot?

Only the possibility of bending pins or inserting the chips backwards. With care, though it can safely be done.