How to change Vdd for digital IO's on eval board

Hi,

if you are using MSP-FET430UIF and CCSTUDIO please refer this short online video:

http://www.youtube.com/watch?v=t2BJaRRzdFw

For IAR it should be more or less the same:

Thank you, that was easier than I thought. But when I connected the batteries to the board, the voltage went back down to 3 V. I tried changing the build configuration to "release" but that didn't help. (I'm using CCS)

Have you looked at the board schematic?

http://www.ti.com/lit/ug/slau278m/slau278m.pdf

you can change the supply source by changing JP2:

Yes, I always change that jumper when I switch to battery power. I also had the JTAG disconnected, because I'm going to need the board to be purely battery-powered and free to move around. I've been using the battery packs that came with the kit and plugging them into CON12, but I'm planning to use a lithium ion battery instead. I don't know why the target power changes just because I changed to external power.

Ok, I thought the batteries were arranged in parallel, which made me think that Vdd was being defaulted to 3 V.

That solves my problem then. I didn't know Vdd always changes to the external supply voltage, but that makes sense. The batteries I'm planning on using are at 3.6 V, so I guess I'll be fine.

Thank you for your help. Sorry for being confusing but I'm still learning!

Digital I/O is sourced by the same VDD as the MSp itself. If you supply 3.6V, then the digital I/O runs on 3.6V. If you apply a batery with 3V, it will sink the supply voltage by teh JTAG and draw VCC down to 3V again (and the FET will shut the supply off due to overcurrent when charging the batteries)

If you want to have I/O of 3.6V running on your own supply (not the programmable supply of the FET) then you have to provide 3.6V yourself, not 3V.

You can't eat the cake and keep it.