I notice that the latest offerings in the MSP family feature "Brownout" reset capabilities. I therefore assume TI are aware of this "attribute" of the earlier MSP offerings, and have addressed it accordingly.
I too have seen the problem you mention in some MSP devices. In fact, I have seen this type of behaviour in many devices over the years, not just micro-controllers. It normally happens when the device power is restored BEFORE the power supply sags to some critical lower level. (Between about 1.5 down to about 0.5 volts, where the device has failed in operation, but enough "power" remains to keep the device partially "alive".) Note that since the current requirements can fall so low at low voltages, that "de-coupling" and filter capacitors may take hours to transition between the mentioned extents. (Exponential decay towards 0.0 volts) Because of that problem, I always use a reset controller on MSP devices (since my initial few projects with the MSP430, that is!) (Currently, a DS1816). If your projects require the ultimate in low power requirements, you may find that an external reset controller has a much higher current requirement than the MSP does when in shutdown. (I do not use the MSP for its low power, but for its convenience.) (And, of course, the excellent GCC "C" compiler and associated tools! Thanks to the developers and maintainers of this code!) On earlier projects with the MSP (remember, low power is not an issue for me) I added a 220 Ohm resistor across the 3.3 volt supply to ensure rapid discharge of the supply when the primary power is removed. This effectively cured the reset problems. If you are not worried about wasting a few milliamps on a continuous basis, this may also work for you. Cheers Harry -----Original Message----- From: mspgcc-users-ad...@lists.sourceforge.net [mailto:mspgcc-users-ad...@lists.sourceforge.net]on Behalf Of Kelly Murray Sent: Tuesday, July 13, 2004 4:27 PM To: mspgcc-users@lists.sourceforge.net Subject: [Mspgcc-users] power-on and reset Hello again, I've been doing deployment testing of my system(s) using MSP430's. The problem I have now (which I admit isn't mspgcc specific :) is the chip does not always run when powered-up. If I hit the reset (ground RST pin) after it's got power, it always then starts/runs correctly. In fact, I don't always even need to ground the rst pin, just touching it with some tweezers before making the ground contact, and it will get it going. I have a 83K resistor between +3.0v and the rst pin. I've used a 33K one, same result. TI says use a 100K resistor. Any suggestions? So far, this is killer unreliability! -Kelly Murray ------------------------------------------------------- This SF.Net email sponsored by Black Hat Briefings & Training. Attend Black Hat Briefings & Training, Las Vegas July 24-29 - digital self defense, top technical experts, no vendor pitches, unmatched networking opportunities. Visit www.blackhat.com _______________________________________________ Mspgcc-users mailing list Mspgcc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mspgcc-users
