What the hell is going with RST on msp430g2553

After succesfull debug of my project with msp430g2553 (not launchpad) I faced with a problem on standalone run.

Due do datasheet, /RST pin pull-uped with 47k resistor to VCC. No success.

Than I pulled-down /RST to GND with 2,2nF capacitor without any effect.

After some googling I also soldered 0,1 uF capacitor between GND and VCC but still circuit don't work out of debug.

During the debug /RST has voltage level 3,1 V, in standalone run - 0. It is obvious that problem is there, but how to pull it up correctly?

UPD I also tried capacitors 100n, 4,7uF and resistors 1k, 10k, 0k (direct wire) and source circuit from battaries but with no luck. In debug mode program works perfectly in any of such RC's.

As a programmer I use Launchpad f5529. 

23 Replies

  • This may sound strange or even insulting. But based on what your posting, you did not provide power to it when it is standing alone.

    msp430g2553 is a "low-power device", not a "no-power device". It needs power.
  • In reply to old_cow_yellow:

    Hehe, good comment :) But standalone power was OK. Firstly I tried with Launchad's power pins, same as used during debug (didn't disconnected circuit at all), than I used two different batteries with 2.9v and 3.57v voltage. I'll post a schematic for more details..
  • In reply to old_cow_yellow:

    So this is the schematics. It is very simple application: using DS18B20 temperature sensor MCU periodically measures temperature and if it higher than needed sends a kind of "TURN ON"command  to my A/C via IR LED. As I mentioned above everything works perfect during the debug mode.

    Thanks for your reply.

  • In reply to Sergii Matsiievsky:

    The schematics look fine. But you did not show the battery.

    When all connected in the stand alone mode.

    1. What is the measured voltage between the battery + and – terminals while in use?
    2. What is the measured voltage from a to b?
    3. What is the measured voltage from c to b?
    4. What is the measured voltage from d to b?

    Your first posting says: During the debug /RST (d) has voltage level 3,1 V, in standalone run - 0.

  • In reply to old_cow_yellow:

    1. The transistor in the schematic exchanges its `e' and `c'?
    2. Why not use the temperature sensor in 2553 directly just like TI demo?
    3. Can the port drive HL1 without the transistor?
    4. With no RST switch, are R2 and C1 needed?
    5. Can the internal DCO/VLO replace the Cr1?

    After all, in the schematic, is everything except 2553 and HL1 necessary? And of course, the battery as pointed out by old_cow_yellow.
  • In reply to old_cow_yellow:

     OCY, thanks for your reply. Here is fresh measurements:

    ab - 3,57 v

    cb - 0 v

    bd - 3,39 v. And this looks very strange! During my first measurements it was always 0. May be I was mistaken yesterday somwhere, or it was because the bad soldering... very strange. I checked the circuit several times.

    So now I can state that RST pin works as it should. But the problem remains the same and nothig happens out of debug. 

    Let me say some words about debug. I have an IR-analyzer made with AVR mcu which catch IR pulses and print timings over rs232. This circuit I use few years to decode RCs and make my own controllers for home automation. So out of debug it catches nothing, my problem is not sounds "I CAN'T TURN ON MY AC", just "my MCU circuit does'nt works %-)

  • In reply to Sergii Matsiievsky:

    Hi Sergii!

    What type of battery are you using? Is it capable of providing enough current? Look at R4 - without the internal output resistance of P3.3, this path would already draw about 30mA. And HL1 doesn't have any current limiting resistor at all. Maybe while debugging you got additional power from the FET, but the battery has too high input resistance. So when the transistor turns on, the supply for your circuit drops, causing a reset, over and over again. You should add a resistance for HL1 and you should also increase the resistance of R4. If the current gain isn't enough, use a Darlington NPN or a FET. Do you have a bench supply? I would test if the circuit works with a higher current capable supply.

    And add some decoupling capacitors to the MSP's supply pins - a 10µF + 0.1µF in parallel would be OK.

    VT1 has a wrong orientation, but I think you already noticed that.


  • In reply to small_stone_head:

    small_stone_head, thanks for you interest and questions.

    The transistor is used simply as a digital switch, because of high LED current consumption - 50mA in my case, so I risk to burn our the MCU if connect it directly. Connection throug resistor will decrease distance of remote control.
    I prefer use external temperature sensor because of its precision and some added feautures (like using 2 and more sensors or internal alarm signal).
    The R2C1 needed to pull RST pin higher. Before it happens MCU can not start.
    Cr1 is used for accurate and useful calculation of time delay. Most time of working cycle MCU should be in LPM3 mode, and the crystal is used to count seconds with low power consumption. Few added pennies are not the case :)

    Regards, Serge.
  • In reply to Dennis Eichmann:

    Hi Dennis! Thanks for your comment.

    I tried to run this circuit with Launchpad's supply pins, CR 2032 battery, Nokia battery BL-5CA (3,58v), 2 AAA elements without any luck.

    To check your suggestion about current draw I totally removed transistor, 100 Ohm resistor from its' base, IR LED and even DS18B20 sensor and changed the program to send some number through UART periodically. The result is still the same - the device works only during the debug session. And yes, I added decoupling capacitors to the MSP's supply pins - a 10µF + 0.1µF in parallel. Ufff, this is kinda strange))

  • In reply to Sergii Matsiievsky:

    Did you try if a simple blink LED program works?