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Tiva C Series Launchpad TM4C123GXL with DLP-7970ABP RFID

Kristian Doggett
Intellectual 320 points
Other Parts Discussed in Thread: DLP-7970ABP

I am having trouble getting the 7970ABP RFID module to work with my Tiva C Series Launchpad TM4C123GXL.

The product information states: Compatible with the TIVA C Series LaunchPad.

I am connected to the Launchpad in debug mode and my COM port is "Stellaris Virtual Serial Port (COM3)".  When I attached the 7970 with pin 1 to 3.3V and pin 20 to ground, the Launchpad will not power on.  The boards are right on top of each other with this pin alignment, as opposed to offset.

  • 0
    Guru 117855 points

    Assuming that your stack of accessory board and launchpad properly connects both 3V3 & ground - and that there are no other "current harvesting" other/unwanted paths - is the accessory board's power requirement w/in the spec of the launchpad's 3V3 Regulator?  (believe that being "compatible" does not insure that adequate power is delivered - in the connection manner you've described)

    It may also be that your USB sourced power proves inadequate for such, "dual board" powering.  (powering from an unpowered hub is the usual suspect)

    As always - do be wary of powering either board "alone" - while both are interconnected.  Makes sense that you confirm the current draw of the accessory board - early releases may not accurately reflect production changes... 

    Realize that - at its price point - it's unfair to expect the launchpad to provide full power for each/every accessory...

  • 0 in reply to cb1_mobile
    Intellectual 320 points

    I can confirm that I am connected directly to the USB port, which should provide adequate power, and the accessory board is connected correctly with pin 1 to power source and pin 20 to ground.

    I will work on confirming the current draw from the accessory board.

    Has anyone ever been able to use the Tiva C Series Launchpad TM4C123GXL with the DLP-7970ABP booster pack?

  • 0 in reply to Kristian Doggett
    Intellectual 320 points

    The 7970A was not working.  Replaced and the board powers on fine.