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looking for a processor

Robert de Boer
Prodigy 20 points
Other Parts Discussed in Thread: XTR116, TINA-TI, SYSCONFIG

I had some help from Raymond Zhang1 on the amplifiers forum "XTR116:xtr116. He suggested that I check with youalls, to see if you have a microprocessor to meet these specs.
 in reply to Raymond Zhang1
Prodigy 10 points

So the signal input is an ac signal from the proximity detector of around 30 mV ac minimum. The turbine is tested that is produces 52.993 pulses (cycles) per gallon. To read gallons per minute is 52.993 / 60 seconds = 0.883216777. The maximum flow is 250 gallons per minute, and should produce 20 mA, the maximum flow is when the proximity sensor reads 220.8 Hz ac / 0.883216777 = 250 gpm.should produce 20 mA. A frequency of 176.6 Hz / 0.883216777 is 200 gpm, half speed is125 gpm * 0.883216777 is 110.4 Hz, and should be 12 mA, the half scale of 4-20 mA. Finally 0 gpm/Hz should produce 4 mA.

So I guess I am looking for a simple microcontroller that has an op-amp input that could be configured as an ac signal zero crossing detector, to count the frequency coming from the turbine proximity detector. This microcontroller scales by a factor of 0.883216777 * 220.8 Hz max, and has an ADC to send a value corresponding to 200 microamps to the XTR11x Iinput pin, to output 20 mA full scale. This micocontroller/processor must run off of the XTR11x VREG pin, and must consume much less than 4 mA. The entire circuit is loop powered by 24 VDC to the XTR11x V+/Iout pins.

Here is something I found, must replace AFE to the XTR116 with processsor to detect, scale and output.

download.mikroe.com/.../4-20ma-click-manual-v100.pdf

Please let me know if you have a microprocessor that fits these requirements.

Thanks,

Robert de Boer

download.mikroe.com/.../4-20ma-click-manual-v100.pdf

  • 0
    TI__Mastermind 26625 points

    Hi Robert,

    So I guess I am looking for a simple microcontroller that has an op-amp input that could be configured as an ac signal zero crossing detector, to count the frequency coming from the turbine proximity detector. This microcontroller scales by a factor of 0.883216777 * 220.8 Hz max, and has an ADC to send a value corresponding to 200 microamps to the XTR11x Iinput pin, to output 20 mA full scale. This micocontroller/processor must run off of the XTR11x VREG pin, and must consume much less than 4 mA. The entire circuit is loop powered by 24 VDC to the XTR11x V+/Iout pins.

    For MSP device,  it currently can not run with 5V power supply, include MSP430 & MSPM0 device.

    If 3.3V power supply for mcu is acceptable, then I will recommend mspm0130x device.

    The input is an analog signal and use the amps to detect the zero-cross point. MSPM0130x have 2 OPAs, 1 GAMP,  and COMP for application.

    Also, I think you need a DAC to output a current signal, rather than ADC, MSPM0L130x series have 8-bit DAC for the application. The max output is 3.3V, you can set a proper RIN for the IO output.

    B.R.

    Sal

  • 0 in reply to Sal Ye
    Prodigy 20 points

    Thanks for your suggestions Sal, yes, I need a DAC output from the processor.

    I am looking for the lowest pin count necessary to do the job.  maybe the MSPM0L1304xDGS20?

    Maybe one of the opamps wired like this:

    This file shows an implementation of the XTR116. 

    www.ti.com/.../tidu299.pdf

    I am looking at the MSPM0L1304xDGS28 16 / 2 in a 28 or, hopefully, a 20 VSSOP package MSPM0L1304xDGS20  would work.

    {In the "MSPM0L130x Mixed-Signal Microcontrollers" data sheet:

    www.ti.com/.../mspm0l1306.pdf

    Section 8.15 COMP:
    The comparator peripheral in the device compares the voltage levels on two inputs terminals and provides a
    digital output based on this comparison. The COMP supports the following key features:
    • Programmable hysteresis
    • Programmable reference voltage:
    – Integrated 8-bit reference DAC, the output can also can connect to OPA input terminal internally as an
    output buffer}

    Can this MSPM0L1304xDGS28 be configured so that one of the opamps is configured as the zero crossing detector shown at the top of this question, and then the internal DAC be configured to run through the other opamp to output to an XTR11x like figure 8.3 of this XTR11x data sheet:

    www.ti.com/.../xtr115.pdf

    Could this MSPM0L1304xDGS28 run from the XTR11x VReg by using a seperate 3.3 VReg?

    I have not used TI processors before, but have read about them. Does this processor work with the Code Composer Studio? Do you have a sample of code that could count the input frequency, divide by 0.88321667, then output using the internal DAC to opamp, to the XTR11x?

    Thanks,

    Robert

  • 0 in reply to Robert de Boer
    TI__Mastermind 26625 points

    Hi Robert,

    Robert de Boer said:
    Can this MSPM0L1304xDGS28 be configured so that one of the opamps is configured as the zero crossing detector shown at the top of this question, and then the internal DAC be configured to run through the other opamp to output to an XTR11x like figure 8.3 of this XTR11x data sheet:

    Yes, it supports the operation you described. but I recommend you check whether the pin function will have some conflicts in DGS28 package, I can help double check it later.

    Robert de Boer said:
    Could this MSPM0L1304xDGS28 run from the XTR11x VReg by using a seperate 3.3 VReg?

    I find that XTR11x only can output 5V, so if you want to use a resistor to reduce voltage to 3.3V, which means that the VDD is not stable and will make imapcts on DAC output. You need check the 3.3VReg range with different load current.

    Or you can set the internal VREF as the DAC source, then I think the DAC will not have much fluctuation.

    Robert de Boer said:
    Does this processor work with the Code Composer Studio?

    Yes, it support CCS.

    Robert de Boer said:
    Do you have a sample of code that could count the input frequency, divide by 0.88321667, then output using the internal DAC to opamp, to the XTR11x?

    As for code example, you can download the SDK and combine several code examples for your application.

    B.R.

    Sal

  • 0 in reply to Sal Ye
    Prodigy 20 points

    I am using Dip Trace for my design. I also downloaded TINA-TI. I am trying to find a component file for MSPM0L1304xDGS28. I cannot find an EDASnp file for MSPM0L1304xDGS28 to use in Dip Trace. Could you send me links? 

    Sal Ye said:
    Yes, it supports the operation you described. but I recommend you check whether the pin function will have some conflicts in DGS28 package, I can help double check it later.

    Could you please check the pin function conflicts?

    Thank you,

    Robert

  • 0 in reply to Robert de Boer
    TI__Mastermind 26625 points

    Hi,

    Robert de Boer said:
    Could you send me links? 

    I am not familar with this, maybe you can connect to the TI-TINA team...

    Robert de Boer said:
    Could you please check the pin function conflicts?

    I recommend you use sysconfig tool to generate the PIN function assignment, and then you can check whether there is any confilcts. Or you can share the syscfg file to me, I might help check when I am avaible, it is quite busy currently.

    B.R.

    Sal

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