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Need help with Propeller and multiple ADC — Parallax Forums

Need help with Propeller and multiple ADC

SSkalkoSSkalko Posts: 9
edited 2010-08-27 00:19 in Propeller 1
I am new to microcontrollers and need some advice. I have an analog circuit for controlling dc loads using PWM from signals generated by thermistors. My analog circuit just seems to grow as I tweak and add in features that function demands. A crucial part of the design is scalability, there are multiple loads controlled by individual thermistors.

I first looked at the Basic Stamp but it seems to lack the capabilities to monitor multiple thermistor values and simultaneously control multiple PWM signals. The Propeller seems like a much better choice with its multiprocessor design.

I have been reading through the Spin and Propeller manuals looking for some signs that this is the right choice if I make the leap from analog to digital. I am excited by the prospect of learning to use the Propeller in my project, especially the ability to bring in GUI later in the project. What I need to know is whether I am barking up the right tree? Does Propeller meet the basic requirements to monitor multiple analog signals? If I have say twelve thermistors can I use the Propeller to get a value at a 60 Hz frequency.

I appreciate any help and feedback that you can provide.

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2010-08-26 22:41
    The Propeller can certainly handle multiple ADC channels. Each cog (of 8) has two counters described in detail in the application note on the counters (AN001) which includes sample programs to implement two ADC channels in each cog. These can provide about 20K samples per second with 12 bit accuracy with really careful attention to board layout and parts placement. You can get better accuracy with less work using an external ADC and the Propeller can manage several external ADCs at the same time.
  • HollyMinkowskiHollyMinkowski Posts: 1,398
    edited 2010-08-26 22:54
    You could use 2 Propellers to handle more ADC channels
    and also create a nice GUI on a monitor and do the PWM. The idea to use external
    ADC with a single Propeller might be easier though. Mike Green
    is an excellent engineer and his recommendation is probably
    the best way to go.
  • TubularTubular Posts: 4,717
    edited 2010-08-27 00:19
    There are some objects in the Obex already that might smooth the transition.
    For instance the MAX1270 object has BS2 routines (I believe)
    http://obex.parallax.com/objects/513/

    There is also a MCP3208_fast for using the 8ch, 12bit microchip ADC.

    I thought there was a MCP3208_fast_multi somewhere too, designed to talk to 3 of these at high speed (24ch)
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