Voltage Stacking with energy harvesting STM32WB55

[methene]

Hello, I am attempting in voltage stacking of 2 STM32WB55 board, but unlike arduino I could not connect Top board's GND to bottom board's 3.3 V pin. I would like to request for help or insights for alternative method I could make it work. I would really appreciate the help. 

Problem

1. When I connect the Top STM32 GND to the VDD of Btm STM32, it discharged the voltage in Btm capacitor.

2. On one attempt I rearranged the circuit in similar stacked configuration, it did not discharged the Btm capacitor voltage. Instead the system goes haywire.

Thank you.

[methene]

Yes I am fully aware the boards are not meant for the purpose of this, is just that my topic are related to voltage stacking of microcontrollers with energy harvesting capabilities. I appreciate any input on how can I make it functionable, but if it is impossible I might have to switch my approach to this.

Thank you very much for you knowledge. Would appreciate if there any other method I could achieve similar result.

[Andrew Neil]

The document you attached showed that this relies on special power supply arrangements within the chip - I really don't think it's something that you can apply to an existing chip or board which does not have that designed-in.

[methene]

Yes the documents I had sent is on the transistor level of voltage stacking, which are more common. My goal is to find out if it is possible for off-chip implementation of voltage stacking, especially energy harvesting voltage stacking. Which I was able to achieve with arduino, and I don't think arduino is made with this intention as well. Hence the obnoxious connection, I know it looks crazy but I was able to achieve halving of current which was a point mentioned for the advantage of voltage stacking. 

If it is really impossible with STM32 board to do that arrangement, I have to revise my research goals and objective. 

[Andrew Neil]

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@methene wrote:

 I was able to achieve halving of current  

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but at the cost of doubling voltage - so no actual gain in power / energy ?