Suggestion for future revisions of EK-TM4C123GXL launchpad Tiva.

Hello rrom,

There is the Header jumper between H24 and H25. If the same is removed then the H24 can be used to give a VBAT supply from a coin cell or an external supply, while 3,3V still can come from the on board regulator which can be used during Hibernate Mode VDD3OFF.

Regards

Amit

Amit

You absolutely right. But This causes the obligation to manually remove the jumper H24 - H25 to connect an external supply during hibernation mode.

Only by going directly to the VBAT pin as I suggest, it would use the hibernate mode without VDD3ON. (full functions RTC)

Regards

Hello rrom,

The VBAT has to be supplied during board setup and not during hibernate mode. Also for users not using the Hibernate function, wouldn't it be a manual effort to put H24-H25 jumper back in?

If probably I am not able to understand what you expect, can you visually draw and send it across?

Regards

Amit

Believe both parties make fair/reasoned points - and that there is a, "joint solution!"

Simply add a board build - suffixed with "hib" - which includes H24-H25 jumper in a bag - rather than installed.  Thus - both masters are served.

Reality intrudes - suspect that those using hibernate are in the (great) minority - thus vendor's current implementation meets the "majority need."  (same cannot be said for the, "dreadful" 0-ohm R - MCU-MCU enforced connections!)

Yes VBAT must be supplied during setup of the board.
What I'm trying to explain is that in the current configuration, it is not directly possible to apply an external power supply (a battery, for example) on the H24 pin to permanent power VBAT if  jumper H24 and H25 is closed.

If H24-H25 Jumper is open, yes it's possible to supply VBAT for Hibernation. But Run mode for MCU is not possible.

An simple application example:

- Tiva MCU Run in normal power mode.
- It configure Hibernation Module and RTC to Wake up from RTC Match (after predefined time) 
- Then enter in Hibernate Mode (Only RTC supplied by VBAT is supplied), Main power can be removed to have lowest power consumption.
- Return in Run Mode after Wake up and mai  supply restored and continu again...

The best Low Power Mode

I hope to make me understand. 
 

Regards

Hello rrom,

Thanks for the explanation and yes, it does clear up the confusion.

To clarify the point if the H24-H25 is removed then MCU can still continue to run in RUN Mode without Hibernate Function. Please note that in the absence of VBAT the Hibernate module will switch to VDD supply as it runs of the higher of the two supplies.

The +3.3V comes from a LDO on the LaunchPad and so if USB is connected then the VDD and VDDA will be supplied as well.

Regards

Amit

Amit,

How MCU can still continue to work in RUN mode if H24-H25 jumper is removed ? You mean you need to apply an external voltage on H24 only ?

If i learn schematic and datasheet, by removing H24-H25 jumper VDD, VDDA are longer supplied because VDCC is not supplied too by internal LDO of MCU.

Correct me if I'm wrong !

Regards

Please also look at the DK-TM4C123G board. This board uses the external battery a CR2032.  It also has an example of the external logic required to account for all corner cases.

I think TI has offered all along (and even before the Launchpad) the solution the poster originally suggested.

Hello rrom,,

My apologies. I was looking at the schematic as VDD and VDDA coming from +3.3V.

You are right, VDD3OFF is not possible (the lowest-lowest power mode).

Regards

Amit

The 129 Launchpad should also have the zero ohms and test points needed to make this simpler.  it is by default VDD33ON mode only but can be re-configured.

The 123 Launchpad does not support VDD33OFF mode.

The over all philosophy of Launchpad was to be as simple as possible with as few jumpers as possible.  As the board reaches out to a group of developers who are less familiar with embedded debugging thus simplicity was a critical factor.

Dexter

Amit Ok, no problem

Dexter thank you for the info on the VBAT on the DK-TM4C123G
I am aware, objective of low-cost EK-TM4C123GXL vs to its big sister

So here is the goal of my suggestion in my first post.

Thank you all for your reply