MSP430-1611 get time since last reset

Hi fred,

some MSP430 devices feature a real time clock (RTC) --> http://focus.ti.com/paramsearch/docs/parametricsearch.tsp?&familyId=342&uiTemplateId=PP-T-GSPA_T&techFamId=null&rootFamilyId=null&sectionId=95&tabId=1200&appId=null&viewDeviceCallingPage=null&totalCount=299&showAdditionalParameters=no&parameter=2544704423&lc=2000062&lc=2001227&lc=2001220&lc=2001219&lc=2000886&lc=2000121&lc=2001132&compare=yes&download=yes&sort=yes&customize=yes&paramResults=yes&paramCriteria=yes&familyTree=yes&military=no&baSystem=yes&paramTable=no&sortOption=PA_SUB_FAMILY_NAME&sortMode=DESC&searchPaths=1000342&pageId=342&templateId=0&navigationId=0&family=mcu&paramTable=no&military=no&&uiTemplateId=PP-T-GSPA_T&techFamId=null&rootFamilyId=null&sectionId=95&tabId=1200&appId=null&viewDeviceCallingPage=null&resetCompare=true#sdp

You will need to use a 32kHz crystal to feed it, but it will give you an accurate timing.

Rgds
aBUGSworstnightmare

ok but msp430F1611 is not in the list

I think I must use a timer to do this task, or see if there is already a time counter incremented in contiki stack

The usual way is to set up a timer for a preiodic interrupt (e.g. 1ms). In this interrupt, you increment a counter variable that finally gives you a time since startup. The accuracy depends on the source clock accuracy of the timer.

For projects, where I need a real time, I have added an external PCF8583 with I2C bus, powered by a gold cap. With a separate crystal and adjustable capacitor, you can bring it to almost any accuracy you want. In the MSP, I read the RTC at startup and every minute, calculate the difference between internal, timer-driven time and RTC and adjust the timer settings by a tick if necessary. Gives excellent long-term results. (I do it identically for an ATMega based access point as well as for our MSP based logging metering devices.)

Maybe there's a counter of the above type already inplemented in teh COntiki stack. I don't know. Most OS-like codebases implement at least a millisecond counter. Some even provide a time/date conversion based on it. It won't be, however, as acurate as a real RTC.

Thanks for your reply

I have solved this problem

Is there a branch of the forum for contiki (and msp430)

I think msp430F1611 can deliver their remaining battery and temperature, is it right? I'm looking to get a driver to read this values (using contikiOS)

The ADC12 inside the 1611 can measure an internal temperature diode as well as its VCC/2. The values need to be taken using one of the internal reference voltages (since measuring VCC/2 against VCC doesn't make sense)

It's not simple, however, to measure remaining battery. All you can do easily is measuring the battery voltage (which depends on remaining charge and momentary load).

Jens-Michael Gross said:

For projects, where I need a real time, I have added an external PCF8583 with I2C bus, powered by a gold cap. With a separate crystal and adjustable capacitor, you can bring it to almost any accuracy you want. In the MSP, I read the RTC at startup and every minute, calculate the difference between internal, timer-driven time and RTC and adjust the timer settings by a tick if necessary. Gives excellent long-term results. (I do it identically for an ATMega based access point as well as for our MSP based logging metering devices.)

Could you share sample code for i2c communication with PCF8583? I use 2553, and  I try to use i2c lib from TI example slaa382. It was not suitable (no restart). After i tried i2c lib from slaa386a. Tx/Rx interrupt occurs after ending TI_transmit() function execution, some bytes lost. 

Bloom said:

Could you share sample code for i2c communication with PCF8583? I use 2553, and  I try to use i2c lib from TI example slaa382. It was not suitable (no restart). After i tried i2c lib from slaa386a. Tx/Rx interrupt occurs after ending TI_transmit() function execution, some bytes lost. 

OK, I found solution yourself, and I can tell everyone, who want :)