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Found 5 results

  1. The example msp430fr5994x_lpm4-5_02.c is supposed to show how little current is used in this mode. In the file it says: // MSP430FR5x9x Demo - Entering and waking up from LPM4.5 via P1.3 interrupt // with SVS disabled // // Description: Download and run the program. When entered LPM4.5, no LEDs // should be on. Use a multimeter to measure current on JP1 and // compare to the datasheet. When a positive voltage is applied // to P1.3 the device should wake up from LPM4.5. This will enable // the LFXT oscillator and blink the LED (on P1.0). Even for a high-end multimeter this current is too low to be accurately measured. So I helped myself this way: - power the processor from the supercap - a 10k resistor with two antiparallel diodes act as a shunt, - connect the volt meter across the supercap, not across the processor 0.43mV over a 10k resistor gives 43 Nanoamps. (!) Yes, the datasheet (page 32) is right, typical value at 25°C is 45nA. A CR2032 (200mAh) cell would allow the processor to wait for an interrupt for 530 years.
  2. Hi, my name is Fabian an im recently working on an MSP430 project with the Launchpad MSP-EXP430G2 and Energia 0101E0017. I have an TEG Harvester and want to run the MSP that sends data via a NRF24l01 module. Everything works great, current is really low in working and in sleeping mode. But now the problem: When i apply power to the chip (3,3V) it draws significant current for about 2 seconds. Then it starts working normal and the current drops and stays low as long as you don't remove the supply and start again. This is really bad for energy harvesting applications, because you need a much bigger harvester just because of that power up current that just happens sometimes. Is there a setting for the startup time? Please see my attached code. Thank you so much, Fabian PPEH.ino
  3. I've run into an issue with execssive current usage on the Launchpad. My goal is to run a sensor on a battery for at least a year. The initial test was promosing because the launchpad (with J3 jumpers removed of course) was drawing barely a uA in LP3 sleep mode using the sleepSeconds() function in Energia. I was thrilled. Then I figured that I should keep tabs on the battery level. To do this, I had to set analogReference to INTERNAL2V5 and use analogRead(11) to get the value. It works great. Below is a barebones snippet. The problem is that the current usage jumps to 180uA even in LP3 sleep mode. I understand that there will be some current usage to get the reference voltage, but it never turns off. Even if I set analogReference back to DEFAULT after the analogRead and call sleepSeconds. Can anyone explain this? I'm hoping I'm doing something wrong. void setup() { // Use the 2.5V internal reference analogReference(INTERNAL2V5); //analogReference(DEFAULT); } void loop() { // Get battery voltage //analogReference(INTERNAL2V5); int v = analogRead(11); //analogReference(DEFAULT); sleepSeconds(10); }
  4. In at least two places the Energia documentation claims that LaunchPad pins can source or sink up to 40 mA. Is that true of all (or any) of the launchpads supported by Energia? (i.e., Stellaris/Tiva, Tiva Connected, MSP430, Fraunchpad, C2000, CC3200) For the Stellaris launchpad, the documentation for the LM4F120 gives drive strength options of 2, 4, or 8 mA, and says up to 4 pins can sink 18 mA. So where does the 40mA come from (or go to)? Yet energia.nu says: "LaunchPad pins can source (provide positive current) or sink (provide negative current) up to 40 mA (milliamps) of current to other devices/circuits." http://energia.nu/guide/tutorial_digitalpins/ http://energia.nu/reference/constants/ I note that the Arduino documentation says the same 40mA, so suspect this specification may have accidentally been copied from the AVR. If so, seems like an invitation to release the magic smoke. Please someone either point me to where the documentation says that the various launchpads can source/sink that much, or fix the web site to either include the actual numbers for the various launchpads, or remove the misleading number. I previously posted this question on stellarisiti (where it failed to generate any action), but just noticed that the web site says to post documentation corrections on the 43oh Energia forums.
  5. In the energia tutorial it says that "LaunchPad pins can source (provide positive current) or sink (provide negative current) up to 40 mA (milliamps) of current to other devices/circuits. " http://energia.nu/Tutorial_DigitalPins.html Is that correct for the Stellaris Launchpad? In the documentation for the LM4F120 it gives drive strength options of 2, 4, or 8 mA, and says up to 4 pins can sink 18 mA. Where does the 40mA come from? Can the MSP430 source/sink that much? I note that the Arduino documentation says the same 40mA, so wondered if this specification was accidentally copied from there.