LC Doesn't Repond to Reset Button

[emarsh]

I'm doing some work with an LC using both i2c channels. Sometimes the LC will hang and pressing the reset button won't bring it back so I have to pull and replace the power lead.

This is not a huge problem but I'm curious as to why this might be happening.

Also, this morning I noticed that when I attach a logic probe to the LC and run my program that uses i2c to pass data between the Teensy and a Pi after a few seconds the Teensy hangs and won't come back. The probes are properly grounded and the behavior stops when I remove them. Any ideas why?

Thanks,

Eric

[KurtE]

Actually there is no reset button. The button is actually a "Program" button, and when pressed puts the teensy into program mode waiting for a new program to download.

As for why hang, not sure... What type of logic probe,... Also helps to have more information, program code...

[emarsh]

Actually there is no reset button. The button is actually a "Program" button, and when pressed puts the teensy into program mode waiting for a new program to download.

As for why hang, not sure... What type of logic probe,... Also helps to have more information, program code...

Well - that's useful.

My hang problem with the probe went away. The probe is a Saleae Logic 8. I've noticed that the Teensy is sensitive to anything that might degrade the i2c signal. The probe has about an 8" lead - I've got another 8" from there to the breadboard. Then there is are 4" leads between the LC and the Pi.

I'm using the Pi to power the LC and a few sensors. I wonder if voltage might contribute to things.

My code is nothing spectacular on the Teensy side. I'm using Wire and Wire1. This is the bulk of it:

// In setup

// register events
  Wire1.onReceive(receiveEvent);
  Wire1.onRequest(requestEvent);

// In body
//
// handle Rx Event (incoming I2C request/data)
//
void receiveEvent(size_t len)
{
  if (Wire1.available())
  {
    addr = Wire1.readByte();
  }
}

//
// handle Tx Event (outgoing I2C data)
//
void requestEvent(void)
{
  Wire1.write(mem[memPtr][addr]); // fill Tx buffer (from addr location to end of mem)
}

[Ben]

I ran into this problem when I powered the teensy from an isolated power supply, it was very sensitive to touching anything connected to it. When I inserted a USB cable (for data connection, VUSB cut), the problem vanished, I guess because the system now had a proper GND connection to the rest of the world through the USB GND.

[emarsh]

I ran into this problem when I powered the teensy from an isolated power supply, it was very sensitive to touching anything connected to it. When I inserted a USB cable (for data connection, VUSB cut), the problem vanished, I guess because the system now had a proper GND connection to the rest of the world through the USB GND.

Thanks for the tip - I'll take a look at that.