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CC2538 Technical Doubts

AlvJorge
Intellectual 575 points

Other Parts Discussed in Thread: CC2538

Hi,

designing for CC2538 platform I have found some doubts I expect you could help me with.

  1. Power.
    1. Power Source.
      1. Having different power sources, an external DCDC regulator has to be added. So, regulator's output voltage has to be selected, as well for CC2538 supply voltage. Reading on datasheet, I can't find any about power consumption evolution in function of supply voltage. Abstracting from other parameters (ie. CPU frequency), which would be the differences of work at different voltage levels (2.5V or 3.3V)?
      2. Would the supply voltage affect to GPIOs levels? If I decide to power CC2538 with 2.5V, could it deliver 3.3V at outputs?
    2. Power Consumption.
      1. Is CC2538 able to measure its own power consumption internally?
    3. Power Measurement.
      1. If a (3.7V-3.8V) portable battery powers the device, could be the low power comparator module used for measuring battery voltage level?
      2. Is it neccesary to add any extra hardware to do this function?
  2. Peripherals.
      1. I2C.
        1. Could I2C ports be configured at any digital ports?
        2. How many I2C devices can be linked to the same interface?
      2. SPI.
        1. Can the SPI ports be configured at 'real-time' for another purposes? For example, if several components are connected to the same ports, and one has an analog output and another one has SPI protocol communication interface, SPI ports should be 'swapped' from analog to SPI & viceversa (CC2538 has enough ports to not need to implement this, but I prefer to know before thinking in such idea).

    • Xtals.
      1. How is CC2538 avoiding possible issues of having two different external xtals (32MHz & 32.768kHz)? Even, when they are use at different power modes, MCU needs to swap between frequencies at xtal change time.
    • Temp Sensor.
      1. Could the internal Temp sensor be used to read ambient temperature? Or is this sensor only available to read the internal one?

    Regards!

    • 0
      TI__Mastermind 27145 points

      Hi,

      We are looking into it and get back to you ASAP.

      Thanks,

      PM

    • 0
      TI__Mastermind 27145 points

      Hi,

      For question 1.1.1 - As per the data sheet , the toal current consumption is Icore + Iperi. At 3V, Icore in Tx mode at +7dBm = 34mA and add Iperipheral current  (depends upon the peripheral running - for example for USB 3.8mA).

      For question 1.1.2 - Yes, Vdd will affect the GPIO levels. It will lmit to the Vdd level.

      For question 1.2.1- No, it doesn't have an internal power consumption measurement

      For question 1.3.1- Battery voltage monitor can be implemented by using internal A/D. Please refer to section 15.2.1of CC2538 UG (SWRU319C)

      For question 2.1.1 - Yes, I2C ports can be configured on any Digital I/O

      For question 3.1 - Please refer to section 7.2 1of CC2538 UG (SWRU319C)

      For question 4.1 - No, the temp sensor is used to read the temp on the chip.

      Thanks,

      PM

    • 0 in reply to PM
      Intellectual 575 points

      Hi,

      thanks PM!

      One more thing about 1.1.1, just for confirmation. 

      Datasheet is electrical specs are for 3V Vdd, so will I expect that power consumption will be reduced if Vdd is reduced? And at the other side, if I level up the power voltage, will the power consumption rise?

      Regards.

    • 0 in reply to AlvJorge
      TI__Mastermind 27145 points

      Hi,

      Yes, your assumption is right. Please see the following table for details.

      Device Mode Current Drain, mA
      Vdd, V
      3.0 3.3 3.6
      CC2538 Stdby 17.2 17.6 18.1
      Recive 34.0 34.6 35.0
      Transmit 44.6 45.4 45.9

      Thanks,

      PM

    • 0 in reply to PM
      Intellectual 575 points

      Hi PM,

      thanks for your answer.

      It's just what I need.

      Regards.