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Schematic considerations for MSP430?

I know that I've seen a TI document about this before, but a 15 minute google search left me with nothing.

I am double-checking a schematic that uses an MSP430F149, and I want to ensure that I have all the pins correctly terminated for (1) correct operations and (2) access to the JTAG port for in-circuit programming and debugging. Here's what I've got:

AVcc -- 3.3V DVcc -- 3.3V DVss -- GND AVss -- GND XIN -- GND VeRef+ -- GND VeRef- -- GND RST -- Pulled up to 3.3V, with a connector at pin TCK -- Connector at pin TMS -- Connector at pin TDI -- Connector at pin TDO -- Connector at pin

Everything else is open (except for some inputs and outputs that I am using). I am using the internal oscillator as clock.

Any help (whether a reference to a document or a check of my pinout) will be greatly appreciated.

-Chess

Reply to
Chess Saurus
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Hi,

TI have a demo board based on the msp430f149, you can check all the connections against that.

I'm not sure it's schematic is on the web, but i could dig it out for you if your having problems finding it.

Dave

Reply to
David Powell

Not sure about tying RST high. TI's demo schems always use an RC reset in the range 10K-100K (though I think 30K is the "upper limit" according to other documentation) + 100n, and this works in the lab. The MSP's hardware brownout does leave a hole however, so I would recommend an external reset chip as best practice.

You can leave VeRef+ floating. I'd be tempted to do the same with XIN, it might be biassed.

Most of the demo files have a ASCII schematic in a big comment at the top.

Regards, Mike.

--
Mike Page BEng(Hons) MIEE           www.eclectic-web.co.uk
Quiet! Tony's battling the forces of conservatism, whoever we are.
Reply to
Mike Page

Thank you for the offer, but I do have that schematic. The things that I noticed about it is that it has a filter capacitor on the DVcc and AVcc lines, and that it actually connects the XOUT pin to the JTAG port.

I have added a capacitor to mine (100nF ceramic), put have not put a lead on XOUT, because I read elsewhere on USENET That this pin is no longer necessary.

-Chess

Reply to
Chess Saurus

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