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msp430 reset pin problem during programming

Hello myself ankit,

i am using msp430 2272 for my application which contains LCD.

i am programming the MSP 430 2272 using module ez430 which uses 4 pin of the microcontroller. 

1. test

2. reset

3.vcc

4. ground

when i connect the dongle USB to PC and then to my application board containing msp430 it works well. and i can program the msp properly.

But sometime i cannot program the msp and i found that the when i program the MSP reset pin doesnt go low. After that i am not able to program the MSP anytime . then I have to change the MSP . But my MSP is working fine for my last loaded application only problem is that i cant program it anymore.

I am using code composer essentials. as my tool.

My reset pn pullup by 10K resistor. Is there any precaution that i need to take for the for the reset pin.?

waiting for your reply.

3 Replies

  • That's unusual.

    The reset pin shoudl have an additional capacitor of no more than 2.2nF to GND. If it is larger, the reset pulse (or subsequent programming pulses) might be too short to drive the reset line low in time. There is, however, no reasom why a working setup would suddenly and finally fail.

    The only possible reason why there could be permanent failure woudl be physical damage of the chip. Ths may happen if you apply a wrong voltage to the port pin.
    All MSP port pins have clamp diodes whcih wilshortcut overvoltage to VCC ro GND. These diodes can bear up to 2mA. This may be enough to power the MSP through the programming pins, but if these diodes are damaged due to overcurrent (e.g. when the programming lines are high but the MSP is unpowered and the current is not limited), they can melt, causing either a shortcut of the pin to VCC (which could explain why you don't see it pulled down anymore) or break open, so that subsequent overvoltage will damage the port input logic itself.
    In most cases this won't affect the functionality of the rest of the MSP, but without reset pin, you cannot program it anymore.
    Try putting a series resistor (4,7k vor up to 10V) between your programmer and the reset/test pins and see whether the problem persists. And don't leave the MSP attached to a powered programmer without being powered itself for longer periods of time.

  • In reply to Jens-Michael Gross:

    Thanks Jens-Michael..

    will try to do this putting a capacitor less 2.2 nF . May be i was connecting the programmer for for a long period of time . will reply u the feedback and if any problemn persists

  • In reply to ankit patel:

    ankit patel
    will try to do this putting a capacitor less 2.2 nF

    Don't forget the series resistor(s) to ensure the current into the programming pins is below the allowed 2mA under all circumstances.