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Is the bs2 capable of generating an rf carrier (200 khz +) ? — Parallax Forums

Is the bs2 capable of generating an rf carrier (200 khz +) ?

mstrammstram Posts: 49
in BASIC Stamp
Greetings,

I have an old bs2 that I haven't used for "awhile"

I'm wondering if an output pin can be toggled, "outed" , "pulsouted" to the point of generating an RF signal of at least 200 khz?

If not, what's the maximum frequency possible using something like :

Main:
HIGH 1
HIGH 0
GOTO Main

What is the bs2 clock frequency ?

Mike

Comments

  • mstrammstram Posts: 49
    P.s. The only "RF measurement equipment" I have is my Grundig 400 SW receiver :)
  • ElectrodudeElectrodude Posts: 1,660
    edited 2016-04-22 19:17
    Definitely not. The fastest BS2, the BS2px, has a 32MHz clock but can only do ~19,000 instructions/second according to the BS2px product page.

    On the other hand, a Propeller can easily make a 200khz signal. In fact, each of the 8 cogs on the Propeller has two counter devices which can act as oscillators. This means you could have a Propeller generate a 200khz signal entirely in hardware!
  • ercoerco Posts: 20,257
    It's common practice to use harmonics get brief bursts of 38 kHz for IR receivers. Not sure if the harmonics would go much higher. Chris?
  • mstrammstram Posts: 49
    Electrodude,
    Ok, thx, ya I saw the thread on AM and FM Transmitters, which is what gave me the idea of trying the Stamp.

    I've been thinking about buying a propeller board, that Transmitter thread, and the SID thread are two things I want to try.

    Erco, thanks for the link, interesting stuff

    Mike
  • Tracy AllenTracy Allen Posts: 6,664
    The Stamp command
    PWM 0,128,255
    Generates a 111.3kHz square wave which would have lots of odd harmonics. There is not any control over the frequency, but it could be good for something? The Prop is definitely the way to go if you want to do the fancy stuff.
  • mstrammstram Posts: 49
    Tracy,

    What frequencies should I look for the odd harmonics ?

    I tried that PWM command, didn't hear anything on my radio.

    Mike
  • Mike GreenMike Green Posts: 23,101
    Odd multiples of 111.3kHz (like 333.9kHz, 556.5kHz, etc.) Higher multiples will be weaker.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    erco, what Tracy said. ;) This is definitely a case where the BS2 is not the right choice for the application. Now, if it was capable of doing everything else in the design, the the issue could be solved with a small dedicated piece of hardware just for that purpose.
  • mstrammstram Posts: 49
    Ok, thanks for the additional info.

    Still not hearing anything. I tried a random piece of wire ~ 4 feet long as an "antenna", didn't help.,

    Maybe an exact multiple of the 111.3 khz freq's wavelength for an antenna would help ?

    But I bought a propeller on the weekend, and the a.m. transmitter code is working great !
    My Grundig (as expected) generates a nice "morse" sidetone, and I can even hear "morse phumps" on my a.m. clock radio from the propeller ;)

    But I can still use the stamp for some audio stuff, and try programming it to "drive around (BOE with wheels / servos)

    Mike
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