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CC3200 idle_profile LPDS without USB not working

nemanja stefanovic
Prodigy 60 points
Other Parts Discussed in Thread: CC3200, UNIFLASH

Hello,

I'm having an issue with the CC3200 idle_profile example running it from a battery or external 3v power source.

When I flash the example using Uniflash, and connect the board to my machine over USB, the example works perfectly. The red LED turns off to indicate it has entered LPDS and only flashes for GPIO or host IRQ wake-up.

However, when I do all the same stuff using external power, the board never enters deep-sleep. The red LED never turns off and the unit never goes into LPDS. I'm not sure what I'm missing or doing wrong here to induce this. I've tried many jumper configurations as well as using a different UART adapter than the FTDI one, by reading UART from the 20-pin connector.

If anyone has any insight into this, I'd really appreciate it. Thanks!

  • 0
    Prodigy 60 points

    I think I discovered my issue. I was using UART0 to print out debug statements. If I connected the UART to the onboard FTDI module, everything worked as planned, even when externally powered.

    To get it to work right without the jumpers, I removed all of my UART code so the peripheral wasn't even activated or used. By doing that, everything seems to work fine now.

    Is there some way to still be able to expose the UART though externally? Was the problem that I wasn't pulling its pins up or down when not connected over USB?

  • 0 in reply to nemanja stefanovic
    TI__Genius 11120 points

    Can you try with only the UART_TX connected to the USB. So you may be able to see the UART logs. So you need to remove only the J6 jumper.

    The RX line of the device will float and any noise pick-up may be interpreted as a start-bit, so the processor will come out of LPDS. You can also enable the internal pull-up on the RX line to see if that solves the problem.

  • 0 in reply to Prajay Madhavan
    Prodigy 60 points

    Thank you Prajay for your help. I think you're right on that the floating RX line was the problem. I pulled this up externally with a 10K ohm resistor and that seemed to have solved the issue. 

    I couldn't find how to enable the internal pull-up from firmware unfortunately. But I think in my final design I'll do this externally anyway. Thanks again!