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Programme not running on TM4C123GXL Launchpad

Alex Dumitrescu
Prodigy 50 points
Other Parts Discussed in Thread: ENERGIA

Hello.

Hardware: TI Tiva C Series TM4C123GXL Launchpad, TI LM1086IT-5.0/NOPB LDO Voltage Regulator and a 9V battery (a little used).

Software: Basic 'Blink' example from Energia

Problem: The programme does not run when the board gets its power (to VBUS) from the 9V battery, via the 5V regulator (my multimeter reads 4.9V). The LED does not blink at all while the board is powered by the battery. However, the green power LED is on. I did check and the LED blinks when the board is powered by my PC via USB.


Can anyone help, please?

Thank you.

 Alex

  • 0
    Guru 47900 points

    Alex Dumitrescu said:
    programme does not run when ... powered from 9V battery ... via the 5V regulator (my multimeter reads 4.9V

    Did you measure that 4V9 when the board was running?:   (a spent battery may output "ok" when unloaded - not so good when under load!)

    When you introduce power as you're doing - via external means - have you insured that all switches and other board power procedures are fully & properly managed?   Failure to comply w/vendor's instructions may damage board components...

  • 0 in reply to cb1
    Prodigy 50 points

    Hello and thank you for your answer, which was spot on!

    When under load the voltage was 2.6V, so, I replaced the old battery with a new one and now the 'blink' programme works. Thank you for the lesson. Regards,

     Alex

  • 0 in reply to Alex Dumitrescu
    Guru 47900 points
    Spot on - we like that. Thank you for the quick acknowledgement.

    Please do be aware of any vendor-directed "special handling" when you introduce "external power" - as you appear to be doing.
  • 0 in reply to Alex Dumitrescu
    TI__Guru**** 244400 points
    Hello Alex,

    A 9V battery to the input of the TPS7633DRB regulator. It survived but please note that the manufacturing limit on reliability is 6V absolute Max...

    Regards
    Amit