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msp430 for low power application

Started by cellmania December 4, 2008
i am working on a project on wireless sensors....i need a processor where
the clock frequency can be varied during RUN-TIME so as use in low-power
applications....but it must not be as low as is the case in the sleep
mode.

i found that the option of variable frequency is not available in avr
controllers on which i have worked on till now...i was thinking about
msp430 series but i cannot find a relation between clock frequency and
power mode in this processor....

can anyone help me with more info about power control in msp....


On 2008-12-04, cellmania <pulkitpandey1988@gmail.com> wrote:

> i am working on a project on wireless sensors....i need a > processor where the clock frequency can be varied during > RUN-TIME so as use in low-power applications....but it must > not be as low as is the case in the sleep mode. > > i found that the option of variable frequency is not available > in avr controllers on which i have worked on till now...i was > thinking about msp430 series but i cannot find a relation > between clock frequency and power mode in this processor....
I don't understand what you mean by "relation between clock frequency and power mode". AFAIK, there is no relationship: they're orthogonal. The power management features are explained pretty clearly in the user's manuals.
> can anyone help me with more info about power control in msp....
Power is pretty much linear with respect to clock frequency. -- Grant Edwards grante Yow! Boys, you have ALL at been selected to LEAVE th' visi.com PLANET in 15 minutes!!
On Dec 4, 6:08 am, "cellmania" <pulkitpandey1...@gmail.com> wrote:
> i am working on a project on wireless sensors....i need a processor where > the clock frequency can be varied during RUN-TIME so as use in low-power > applications....but it must not be as low as is the case in the sleep > mode. > > i found that the option of variable frequency is not available in avr > controllers
What do you mean by not available? Can't you set the clock prescaler in 16 steps between /1 and /256, for example?
On Thu, 04 Dec 2008 08:08:02 -0600
"cellmania" <pulkitpandey1988@gmail.com> wrote:

> i am working on a project on wireless sensors....i need a processor > where the clock frequency can be varied during RUN-TIME so as use in > low-power applications....but it must not be as low as is the case in > the sleep mode. > > i found that the option of variable frequency is not available in avr > controllers on which i have worked on till now...i was thinking about > msp430 series but i cannot find a relation between clock frequency and > power mode in this processor.... > > can anyone help me with more info about power control in msp.... > >
Do you really need to vary the master clock frequency, or can you just go into low-power sleep mode and then wake back up on either a periodic or externally generated interrupt? That's the strategy that seemed to be pretty much par for the MSP430 course, as I recall. -- Rob Gaddi, Highland Technology Email address is currently out of order
cellmania schrieb:
> i am working on a project on wireless sensors....i need a processor where > the clock frequency can be varied during RUN-TIME so as use in low-power > applications....but it must not be as low as is the case in the sleep > mode. > > i found that the option of variable frequency is not available in avr > controllers on which i have worked on till now...i was thinking about > msp430 series but i cannot find a relation between clock frequency and > power mode in this processor....
In the datasheet for MSP430F135 processor, page 25, chapter "electrical characteristics/supply current": Current consumption of active mode versus system frequency I(AM) = I(AM)[1 MHz] x f(system)[MHz] I(AM)[1 MHz] is about 300 uA. So it's pretty linear and in the ballpark for other types of mcu. The trick of MSP430 is a fast wakeup from sleep and easy change of frequency. If you can live with the internal oscillator (DCO), you can set its frequency according to slau049.pdf, chapter "4: basic clock module" by changing DCOCTL. There are three clock lines: MCLK (clock for processor core), SMCLK (clock for peripherals) and ACLK (second clock for peripherals). Every clock line has a prescaler (DIVM,DIVS and DIVA) which divides DCO clock (/1, /2, /4 or /8). In addition to that, you can stop every clock by setting some bits in the status register. In this case the peripherals and the core are fully static and an interrupt restarts the core clock. cheers Gunther
In comp.arch.embedded,
cellmania <pulkitpandey1988@gmail.com> wrote:
> i am working on a project on wireless sensors....i need a processor where > the clock frequency can be varied during RUN-TIME so as use in low-power > applications....but it must not be as low as is the case in the sleep > mode. > > i found that the option of variable frequency is not available in avr > controllers on which i have worked on till now...i was thinking about > msp430 series but i cannot find a relation between clock frequency and > power mode in this processor.... > > can anyone help me with more info about power control in msp....
Just reading up on them myself. :-) The information on power consumption and modes is split between the individual datasheets and the User's Guide. I don't know which derivative you are researching, but the user's guide for the MSP430x1xxx (slua049f.pdf) has a nice picture of the clockmodule. As far as I understand it, you can only control the frequency of the DCO. But you can switch between different clock sources. There is also a description on which clocks are enabled during which power mode. -- Stef (remove caps, dashes and .invalid from e-mail address to reply by mail) The trouble with heart disease is that the first symptom is often hard to deal with: death. -- Michael Phelps
cellmania wrote:
> i am working on a project on wireless sensors....i need a processor where > the clock frequency can be varied during RUN-TIME so as use in low-power > applications....but it must not be as low as is the case in the sleep > mode. > > i found that the option of variable frequency is not available in avr > controllers on which i have worked on till now...i was thinking about > msp430 series but i cannot find a relation between clock frequency and > power mode in this processor.... > > can anyone help me with more info about power control in msp.... > >
The DCO (resistance controlled oscillator) can be varied dynamically, and its basic frequency changed by switching between the internal resistance and an external one. The crystal clock can be turned off, and some variants have two crystal oscillators, so one can be a high frequency clock while the other runs from a 32kHz crystal. In addition, you can slow down (via 1/2/4/8 selectable dividers) or turn off clocks to the peripherals. There are also 5 low power modes: LPM0 - The CPU is disabled. LPM1 - The loop control for the fast clock (MCLK) is also disabled. LPM2 - The fast clock (MCLK) is also disabled. LPM3 - The DCO oscillator and its DC generator are also disabled. LPM4 - The crystal oscillator is also disabled. with decreasing power, but increased wakeup time, as the number rises. (partly from http://mspgcc.sourceforge.net/manual/x641.html) It's all in the appnotes on the TI website, though rather distributed all over the shop. JS
On Dec 4, 9:08=A0am, "cellmania" <pulkitpandey1...@gmail.com> wrote:
> i am working on a project on wireless sensors....i need a processor where > the clock frequency can be varied during RUN-TIME so as use in low-power > applications....but it must not be as low as is the case in the sleep > mode. > > i found that the option of variable frequency is not available in avr > controllers on which i have worked on till now...i was thinking about > msp430 series but i cannot find a relation between clock frequency and > power mode in this processor.... > > can anyone help me with more info about power control in msp....
Variable frequency is allowed in AVR's and MSP430 down to very low frequecies with near linear power reduction. Other processors you can't do this (ARM Cortex for instance). TI has a neat wireless MSP430, called the CC430 you may be interested in, see http://www.ti.com/corp/docs/landing/cc430/index.htm
In comp.arch.embedded,
steve <bungalow_steve@yahoo.com> wrote:
> > TI has a neat wireless MSP430, called the CC430 you may be interested > in, see > > http://www.ti.com/corp/docs/landing/cc430/index.htm
"Has" may be a bit optimistic if you want to start development now: "The first CC430 samples will be available in limited quantities in 1Q09 with mass-market sampling and further device introductions scheduled for later in the year" Shame actually, since it would be an ideal fit for what we are starting now. Currently investigating msp430+cc1050 as the cc1050's internal 8051 is a bit power hungry if you want any osc running in power down. -- Stef (remove caps, dashes and .invalid from e-mail address to reply by mail) Did it ever occur to you that fat chance and slim chance mean the same thing? Or that we drive on parkways and park on driveways?
> Shame actually, since it would be an ideal fit for what we are starting > now. Currently investigating msp430+cc1050 as the cc1050's internal
Why cc1050 and not cc1101?