Square wave generation

ANIL KUMAR

Other Parts Discussed in Thread: MSP430G2553, MSP430WARE

Hello,

i would like to generate 6 different frequency square waves at a time , from MSP430g2553. Anyone can help me? frequency should be accurate.

over 11 years ago

0 Todd Anderson78572 over 11 years ago

Guru 14640 points

Somewhat possible using Timer0_A3 and Timer1_A3 - you can set up PWMs from those timers, but not sure you can get to 6. I know you can get 4 square waves easily, but not sure about the other 2. Take a look at the Timer examples for PWM outputs.
If you are trying to drive a 3-phase motor with those square waves, you may want to consider the C2000 processor, which is tailored for that...

0 ANIL KUMAR over 11 years ago in reply to Todd Anderson78572

Prodigy 50 points

sir,
thank you for your concern.
sir, i want to generate some square waves with different frequency.4 is OK. Can you give me the code ?

0 ANIL KUMAR over 11 years ago in reply to ANIL KUMAR

Prodigy 50 points

Sir,
can you send me one example code ,please

0 Todd Anderson78572 over 11 years ago in reply to ANIL KUMAR

Guru 14640 points

If you pull down MSP430ware_1_95_00_32, one example is at
c:\ti\msp430\MSP430ware_1_95_00_32\examples\devices\2xx\MSP430G2xx3_Code_Examples\C
msp430g2xx3_ta_16.c (Single PWM output using timer A1 - can be changed to do 2 outputs.)
You can also add a second timer to do a similar thing for A0 - sorry, I do not have a G2 Launchpad, but I will leave some of the work for you. You should be able to attach an oscilloscope to the outputs to determine how close the square wave outputs are to what you want. I would start with the _16 example, then add additional PWM outputs...
Hopefully that helps.

0 old_cow_yellow over 11 years ago

Guru 58965 points

Quit a few others have asked the same or very similar questions before you. They usually end up with: "Well, I do not want the CPU to do it, I want the CPU to go to sleep". In that case my answer is: "No, there is not enough Timers in G2553 to do that."

If you express the periods you want to generate in fractions and the least common denominator is slower than a few kHz, then you can generate them with the CPU and a Timer (G2553 has two Timers). Can you make a list of the periods (or frequencies) you want?

0 ANIL KUMAR over 11 years ago in reply to old_cow_yellow

Prodigy 50 points

sir,
thank you.
23KHz
33KHz
44KHz
48KHZ

0 Todd Anderson78572 over 11 years ago in reply to ANIL KUMAR

Guru 14640 points

OK, it might take 4 Launchpads to do this, because there is not a high enough frequency to cover all 4 of these...unless OCY has a better idea...

0 old_cow_yellow over 11 years ago in reply to Todd Anderson78572

Guru 58965 points

I was talking about "a few kHz". 23, 33, 44, and 48 are all tens of kHz, no deal.

In this case, it takes at least 4 TIMERs to do it.

0 ANIL KUMAR over 11 years ago in reply to old_cow_yellow

Prodigy 50 points

Can you send me an example code using timers?

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Square wave generation