MSP430 Spy-By-Wire recommended connections

Hi Ayman,

please refer to the following wiki page for the recommended MSP430 JTAG connections:

http://processors.wiki.ti.com/index.php/JTAG_%28MSP430%29

Hope this helps.

Thanks for respond,

OK, I do not like to leave floating pins unless it is a must.  I have connected a 50K, pull up and noticed that the part gets into a strange mode and starts driving the reset PIN and evntuially lock up uC.  I am afraid if I leave this pin floating It can get inot the unkown state and lock up the controller.

Please comment.

Regards,

Ayman

Ayman,

could you please describe what is the problem which you are facing? Which device are you using specifically? What i understand is that your code somehow does not run properly (locked up). If it is the problem, here are some check list:

- have you turned off the WDT at the beginning of your program? per default, WDT is active after reset.

- have you made sure that you are operating the MSP430 on the frequency that complies to the supply voltage Vcc? basically there is a minimum supply voltage requirement to run the device on higher frequency.

- Have you tried to run our example codes? This code has been tested and shall work on our development boards.

- Have you read the MSP430 Software coding techniques? It has some good tips regarding basic MSP430 programming.

Hope this helps.

-Leo-

For most F2xx small pin number MSP430, there is a weak internal pull-down resistor built-in to the TEST/SBWCLK pin.

That pin will not be "floating" simply because you do not connect anything to it. There is no reason to dislike that. Be rational.

Adding a weak external pull-up in parallel to the internal weak pull-down does not make any sense.

If you have evidence that the built-in pull-down is too weak, you may add an external pull-down or even ground it.

This is the information that I was missing, I did not know that there a weak pull on the RST/SWBCLK pin.  I wish that TI would do a better job explaining the programming pins internals in their doucments.  I did not see it in the product spec, do you know where can I find this information for future reference.

Thanks

Ayman

In the data-sheet of the chip (and probably other places too, but I am do not know anything about FaceBook, U-tub, Blobs, etc.).

Look for JTAG Interface and you probably will find:

RInternal, Internal pulldown resistance on TEST: min 25, Typ 60, max 90 kΩ

Hi Ayman,

The exact connections that should be made for programming the part are listed in the Hardware Tool's User's Guide found here. see Figure 2-1 on p. 25 for the 4-wire JTAG connection schematic, and Figure 2-2 on p. 26 for the Spy-bi-wire JTAG connection. This lists all necessary resistors and caps on the SBW pins, and we recommend that you follow this exactly to ensure the best results. There is also information about the connections of unused pins in the 2xx User's Guide on p. 44 that you should also follow. I hope that this helps!

Regards,

Katie

ayman hajmousa said:

I have connected a 50K, pull up and noticed that the part gets into a strange mode and starts driving the reset PIN and evntuially lock up uC.

Yes, because high it the active state. If you insist on adding a resistor, it should be a pulldown. However, the key on this pin is the input current, not the voltage. So it won't catch radio waves, unless you have a long wiore connected to it and are near a radio station.