lpcxpresso 1769 in halves - voltage

[lpcware]

Content originally posted in LPCWare by dragilla on Fri Dec 23 12:00:40 MST 2011
I'm having doubts now. In some sources it is said that the board is powered by 3v3: "Power 3.15V-3.3V external powering, or from USB via JTAG probe (LPC-LINK)". The getting started guide says on the schematic for lpcxpresso1769: "VIN (4.5-5.5V).
When I measure the voltage coming from lpc link to the target board - it's 5 volts.
So the question is: when I split the board in half, which voltage should I supply? 3v3 or 5v? And where do I connect this voltage to... maybe this is the question...? Directly to VIN?

regards and MERRY CHRISTMAS TO EVERYONE! :)
--
Luke

[lpcware]

Content originally posted in LPCWare by NXP_Europe on Sat Dec 31 08:04:15 MST 2011
Hello dragilla,

in the Embedded World it not only very 'handy'... I would say: strongly advisable ... to be able to read electronic designs.

Start by reading 'simple' magazines or books.

Standard 'embedded schematics' can be difficult to read. You have to gain some experience.

[SIZE=2]"Motivation is what gets you started. Habit is what keeps you going."
[/SIZE]

[lpcware]

Content originally posted in LPCWare by dragilla on Wed Dec 28 15:56:11 MST 2011
Yes, I have some trouble reading the schematics and the documentation is far from user friendly (especially a non-specialist), but I will give it another try. If I just had some more time :)
Anyway, sorry for asking silly questions and thank you for your time.

[lpcware]

Content originally posted in LPCWare by Rob65 on Wed Dec 28 15:19:34 MST 2011

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Quote: dragilla

Sorry, but this is really confusing me...

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Both Zero and I have pointed you to the board schematics, data sheet and user manual.
I suggest you read those and try to figure out what happens.

Zero already answered your questions.
I assume you did connect the lpc1769 module to your PC and you did try to run a few sample programs. What happened? Did it work, was the LED flashing when you downloaded Blinky? And did it work even though you did not supply a Vbat? And did you see that both the data sheet or user manual mentions the Vbat pin and what to do with it (yes - it's in there, I read it but just don't remember which of the two documents it was).

You should be able to answer all your questions your self by checking the documents. If you are not able to read the schematics or understand what to do then maybe, just maybe, you are better of with a complete solution like and RDB1768 or an Embedded Artists Base Board.

Rob

[lpcware]

Content originally posted in LPCWare by dragilla on Wed Dec 28 12:19:21 MST 2011
I wasn't using RTC so far and I don't think I will need it. The question is can I leave the Vbatt unconnected or do I have to connect 3v3 to it? Some devices won't work if Vbatt is not connected.

The other thing that is unclear is how it works when connected (not split).
You said that normally the 3v3 is produced by the lpc-link ("VIN of target board is supplying the voltage regulator of LPC-Link (as shown in schematic)"), but this doesn't seem right because if I measure voltages on all 8 pins connecting lpc-link and lpc-target board there is no 3V3, only 5V.
Also the VIN on lpcxpresso is 4.5-5.5V so it seems that 3V3 is produced by lpcxpresso target board after all. If so, then is it possible not to provide 3V3 to VIO_3V3X but 5V to VIN and then use the VIO_3V3X as source of 3V3?

Sorry, but this is really confusing me...

[lpcware]

Content originally posted in LPCWare by Ex-Zero on Wed Dec 28 11:57:29 MST 2011

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Quote: Zero
VIN of target board is supplying the voltage regulator of LPC-Link (as shown in schematic)

If you separate the boards you have to supply 3.3V to PIN28

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What's unclear there? If you separate your target board from LPC-Link VIN is connected to :eek:NOTHING:eek:, so you can connect there anything :rolleyes:

VBAT is VBAT = Battery voltage (coin cell for RTC). Are you using RTC or it's NVRAM?

[lpcware]

Content originally posted in LPCWare by dragilla on Wed Dec 28 11:45:34 MST 2011
Is that enough? :) What about pin J6-2 (VIN / EXT_POWX) and J6-3 (VB - battery supply)? Should I just leave them unconnected?

[lpcware]

Content originally posted in LPCWare by Ex-Zero on Fri Dec 23 15:06:39 MST 2011

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Quote:

So the question is: when I split the board in half, which voltage should I supply? 3v3 or 5v? And where do I connect this voltage to... maybe this is the question...? Directly to VIN?

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VIN of target board is supplying the voltage regulator of LPC-Link (as shown in schematic) :eek:

If you separate the boards you have to supply 3.3V to PIN28 :)