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CC3220MOD: GPIO retention in hibernate and power consumption

jonarnp
Prodigy 75 points
Part Number: CC3220MOD
Other Parts Discussed in Thread: CC3235SF

Table 4-4 in the CC3220MOD datasheet, https://www.ti.com/lit/ds/symlink/cc3220mod.pdf, mention that most GPIOs can be Hi-Z, Pull or Drive in Hibernate. And the footnote on Hib is:
(2) Hibernate mode: The state of the I/Os is Hi-Z. Software may program the I/Os to be input with pull or drive (regardless of active pin configuration), according to the need.

I am not sure I fully understand this, so I have a few questions that I hope will clarify it for me.

  1. All GPIOs that are not configured will be Hi-Z both while MCU is active and in hibernate?
  2. Will a configured GPIO keep its input pull or output drive in hibernate? 
  3. Does 2. require .ioRetentionShutdown = PRCM_IO_RET_GRP_0 or will the IO state remain regardless of ioRetentionShutdown in hibernate? 
  4. When using .ioRetentionShutdown = PRCM_IO_RET_GRP_0, the hibernate current consumption increased 2-3 mA. Is that expected or could it be a HW or SW problem?

  • 0
    TI__Mastermind 22935 points

    Hey Jon-Arne,

    Sorry for the delay. I've been trying to find the answer to your query. You can find my response below:

    1. Correct. While the MCU is active, the GPIOs remain Hi-Z until the application configures them. For hibernate it depends on your I/O retention settings. Here is a screenshot from the prcm.h file about IO retention.

    The pins that are configured as outputs would go into a Hi-Z state since output pins cannot be driven when I/O retention is enabled. The state of the pins that are inputs and belong to the retention group specified by the user (e.g. PRCM_IO_RET_GRP_0), would remain the same state upon entering hibernate and the rest of the pins that don't belong to the group would go into a Hi-Z state (more details about the groups in the screenshot).

    2. Refer to answer above. All input pins would retain their state and output pins would go to Hi-Z.

    3. If I/O retention is not enabled, most IOs will be at Hi-Z. Refer to table 4-2 in the CC3235SF datasheet for more details on specific pins.

    4. When using any I/O retention, it is expected that power consumption increases. PRCM_IO_RET_GRP_0 retains the state of all relevant pins except for SFLASH and JTAG.. I would imagine the power consumption needed would scale depending on the number of pins you are using as inputs but I have not tested this. 

    Hope this helps. I will also follow up via email.

    Jesu