In SX Microcontrollers, SX/B Compiler and SX-Key Tool, DosManDan wrote:

OK, it's me again....
 

I can't seem to debug an SX-28 using 3.03V. I checked the valid operating range and that was definitely in it. I'm using the USB converter connected to the SX-Key which in turn is plugged into the Key Ring. It was my understanding, with the Key Ring I could program and debug at low voltage.

 

I was over at Parallax today and spoke with David and another tech. Both seemed to think I should be able to debug at lower than 5V. One tech suggested that I might have burned out the debug circuit. So, I took the chip out, plugged it into the PDB and it worked fine in debug mode. I plugged it back into the circuit at 3.03V and the debug shows it is running and all of the buttons are grey. That program isn't actually running either.

 

Here are the specifics:

  I am NOT using an external resonator at all

  The Key Ring is powered by 7.5V at 1.2A - Using a Parallax power supply

  The circuit is running at 3.03V - measured at VDD and VSS (at the chip) using a digital meter. I am drawing power from the PDB 5V and using an LM1086 regulator to reduce the power to 3V

  I can program the chip without a problem. I just can't run it in debug mode

  I have taken the chip out, put it in the PDB and it worked fine, so the debug circuit isn't burned out

  I can leave the chip in circuit, change the power to 5V and it works too, so the circuit isn't causing the problem. 

 

Help me tech support, you are my only hope....OK, cheesy StarWars line, but I really need ya. The voice chip I am using only works at 3V, so I don't have the option of using 5V without a bit of extra work.

 

Thanks again,

Dan

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