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the_axis

Spy-Bi-Wire

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I have contructed a simple PWM device that uses a MSP430G2231, I would like to update the software with the JTAG connections on the Launchpad programmer I have. This device has its own power supply. What connections do I need to make beween the Lauchpad and my device? Are the TEST and RST all that is required to use the Spy-Bi-Wire interface?

 

Axis

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Connect TEST, RST and GND. If you do want to also power it from the launchpad, connect VCC. But, don't connect VCC to the launchpad if your target board is powered up.

 

Here's a picture of one of my boards connected like this:

 

imag0245.jpg

 

(I'm also taking TXD and RXD from the launchpad, but they're not connected to the target board, hence the socket+pins in the cable)

 

Take the jumpers off of J4 on the Launchpad and connect to the pins on the FET side (nearer the usb socket). I'm taking GND from one of the headers.

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Well I wired it up and I'm having trouble with it. The external device has its own 3.3v power supply, the reset pin is pulled high with a 47K resistor and a 0.1uF cap to ground. I have connected the ground from the launchpad to ground on the device, TEST to pin 11 and RST to pin 10. When I attempt to debug with code composer I get the error:

 

Error connecting to the target:

Could not find device (or device not supported)

 

If I remove the SBW cables, reinstall the jumpers on the launchpad It will still program the micro in the socket on the Launchpad.

 

Do I have to change any settings in Code Composer to get it to use the JTAG/SBW connections?

 

Axis

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I've only tried in-system-programming with my target board powered from the Launchpad.

My reset pin is tied high with a 10K and no cap.

 

I'm using mspdebug, but I doubt that it'd make a difference.

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Hi the_axis. I think the problem is the cap con the RST pin. Look at the TI document SLAU278, page 22, there is a good schematic showing how to connect the emulator to an MSP430. The upper limit for a cap in the RST pin is 2.2 nF, but I think thats referring to cable or pad inner capacitance. Hope it helps.

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That was it, the capacitor I had from the reset line to ground was creating the trouble. After removing it, the microcontroller programmed fine with just the 2 lines + GND.

 

Thanks for all the help!

 

Axis

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