Question about LM4F232 VDD3ON Mode

Joe,

Can you clarify your question? Are you having trouble getting the GPIO pads retain their state? Are you using the ek-lm4f232 board?

Thanks,

Sean

Scan,

I am using the ek-ln4f232 board,and when I trigger the MCU to Hibernate Mode and set the VDD3ON bit , the GPIO once is high can,t remain their state.I see the HIBCTL register at debug mode for CCS, its VDD3ON bit is set after I code it to set. Could you support  how to take this mode available, please.

Thank you,

Joe

Joe,

You need to modify the board by removing D6 diode.  This will break the HIB pin from power cutting Vdd when hibernate is active.  Also, please check to make sure the 3.0V battery for Vbat is present, and is with in specification parameters 1.8V to 3.6V.   If Vbat is not at a valid voltage level, unexpected results will occur when entering Hibernate.

If you still continue to have issues after removing D6, please let me know.

Lela

Hi Lela,

Thank you for your solution of the VDD3ON mode by LM4F232 EV Board, and I removed the D6 ,this mode worked normally,Now I have another question,when I tested the the power consumpiton of the VDD3ON mode at LM4F232 EV Board, the value is not like the datasheet described, and it is high and small with no regular,sometimes is 20ua,or sometimes is 4ua.   Could you please tell me the cause or give me a demo board of vdd3on and I can tested accurate. Thank you!

Joe

Joe,

Most likely one of two things is happening:  the device is not entering hibernate mode properly or one of the GPIO's is sinking current.

Can you confirm that when you measure the 20uA that the device is actually in Hibernate mode?  Measure the HIB test point next the D6 diode that was removed.  It should measure low.  If it is not low, then the device is not entering hibernate properly. 

What are the GPIO configurations and external pull values in the VDD3ON?  Are you using the Stellarisware example code and just adding the VDD3ON register write?  If you send me your code I can go through a setup here.

Lela

6470.hibernate1.zip

Lela

I tested again, and I confirm that the chip is in HIB mode because the Hib pin is low.The result I test today is 40ua and 200ua. I take most GPIO at defualt confuguration except the GPIOG3,6,7.These three pin I set high in VDD3ON mode.I attatch the code file. Could you please send me a VDD3ON demo board to test and compared, thank you!

Joe,

I will go through a set up here and let you know what my bench findings are.

Lela

Joe,

I went through a set up and took various measurements.  I believe the current spike you are seeing is when the wake signal is asserted, and current gets sourced to ground.  The wake pin is controlled by the select/wake button on the board, and is pulled up by a 220k resistor.  Can you clarify for me if you have made any other board modifications other than D6? 

Note:  You can also remove R33 to further isolate the current consumption at Vbat. 

We have our Stellaris launch pad coming out shortly, and it is set up for VDD3ON mode.  If you order now, it's discounted.  The EK-LM4F232 kit should work and provide accurate data. 

Lela

Lela,

Thank you for your request. I only  take PM0 a 10K resistor to 3.3V so that I can control the MCU into Hib mode.The VDD current is 200ua,and the bat current almost none. I dot not found R33 at this board. Could you please tell me the result you tested when used my code. Thank you!

Joe

Joe,

To obtain a measurement for current consumption for the I_{HIB_VDD3ON} similar to what is in data sheet, measure with a DVM (digital voltage meter) across R32 with resolution set to at least mV.  Then I_{HIB_VDD3ON} = your measurement (mV) / 1k.

Again, remove R33 to isolate power domain.

Lela

Joe,

My measurement for Vbat was off, it was 0.5uA (which does not correlate to data sheet.)  I am looking at external components that are sourcing the current.  I will let you know what I find. 

The EK-LM4F232 was not designed to isolate hibernate using VDD3ON mode, but rather Hibernate with VDD3ON = 0.  The EK-LM4F120 (Stellaris Launchpad) design is optimised to demonstrate hibernate with VDD3ON = 1.  By the time you get the hibernate current isolated by removing components from the EK-LM4F232, you may be better off ordering a Stellaris Launchpad. 

The data sheet value comes from testing done with all of the GPIO's tri-stated, and external components off.

Lela

Lela,

Thanks you very! Jacky has pre-ordered the  Stellaris Launchpad.I will try to test the VDD3ON mode when it reach.

Joe

Great!  Use the qs_rgb project that comes on the CD for a pre-compiled working example of Hibernate with Vdd3on mode.

Lela