# STM32 dev kit: Which power pin, APP or EMU?

I need a voltage source for an external peripheral on my STM32 dev kit. (Reference manual available here.) I see from looking at the extension pins that there are two types of power pins: APP and EMU. (E.g. EMU_3V3 page 22, APP_3V3 page 23.)

What does EMU and APP mean? What is the difference between the pins? Which one should I use to power an external temperature sensor?

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The pins seem to belong to the connector for daughter boards, and I think are regulated voltage outputs. What kind of temperature sensor are you going to use? –  clabacchio May 16 '12 at 9:03

APP_3V3 is connected to the eval board's 3.3V rail.
EMU_3V3 does not actually seem to be connected anywhere, from what I can glean from the schematic (well, the two connectors are connected together, but that's it).
Fortunately, the schematic is saved as a vector-file, rather then images, so you can search for net-labels in the PDF. The only place EMU_3V3 crops up at all is on CN1 and CN3.
Note that this is a pretty freaking terrible schematic. There are multiple power nets, that are connected together. As such, D5V and EMU_5V are really the same net. The same is true for APP_VCC, +3V3, and APP_3V3, which are also all tied together.