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Original question:

MSP430F2252: PMP8740 - Embedded Software.

MSP430F2252: PMP8740 : Schematic and coding related.

Vijay Shinde72
Intellectual 255 points
Part Number: MSP430F2252
Other Parts Discussed in Thread: PMP8740, LMT87

Dear Roberto,

                       Good Afternoon. How are you? Anjana Salgaonkar is on Maternity Leave.

Questions regarding PMP8740 : 4 ADC inputs to MSP430F2252 Controller.

1) Vac Input : On Schematic mentioned 0 to 2 V means 0 to 300 Vac, but in software coding 0 to 2.5 V means 0 to 300 Vac. it is ok 0 to 2.5 V or 0 to 2V range?

Given Vac input to circuit and taken following readings :- 

Therotical Values Practical Values
Sr. No. Calc. ADC
Count		 Calculated Voltage (V) AC
input (V)		 AC1- AC2 (V) Vac-VAC_RTN J2.39 (V) Actual ADC Count LCD Display Voltage (V)
2 98 29 30.32 30.32 0.240 0.240 72 21
3 196 58 50.47 50.47 0.390 0.480 168 49
4 295 86 70.3 70.3 0.548 0.720 284 83
5 404 118 90.2 90.2 0.633 0.988 396 116
6 512 150 110.6 110.6 0.866 1.25 515 150
7 622 182 130.4 130.4 1.045 1.52 632 184
8 728 213 150.6 150.6 1.090 1.78 745 218
9 851 249 170.8 170.8 1.106 2.08 864 253
10 949 278 190.7 190.7 1.247 2.32 964 282

As per above reading,  0 to 2.5 V : 0 to 300 V appeared as per coding. But @190.7 Vac, reach 2.32 V and display 282 V means some hardware problem.

I checked resisters as per schematic, found ok. Please suggest your point of view for Vac circuit checking. Please help.

2) Temperature input :  ADC input (LMT87 IC Output) is 0.538 V(for 150 C) to 3.277 V (for -50 C) is correct or start from 0V ?

3) Battery voltage output and current output as per schematic is 0 to 2V or 0 to 2.5 V? 

 Questions regarding PMP8740 : CAN Communication.

1) is there any person who helps CAN Communication regarding coding? Please suggest.

Thanks and Regards,

Vijay Shinde

  • 0
    TI__Mastermind 29105 points
    Hello Vijay,

    I've notified Robert of this thread, but there may be some delay in response due to the new year.

    Looking at your questions, they seem to be about the PMP8740 hardware design questions. Are there any specific questions about the MSP430 or the board? If not, I may move your thread to the power forum.

    Thanks,
    JD
  • 0 in reply to JD Crutchfield
    Intellectual 255 points

    Dear JD,

                  Thanks for notification. Yes, I understand. Happy New Year.

    Yes, this questions are related with PMP8740 hardware design + coding, so will get it better answer from Roberto Scibilia.

    Happy New Year 2019!!!

    Thanks & Regards,

    Vijay Shinde

  • 0 in reply to Vijay Shinde72
    TI__Expert 6005 points

    Hello Vijay,

    Happy new year to you!

    Sorry for my delayed response but I am just back from vacation.

    Here are the answers to your points:

    1) According to the value of primary side transformer resistors on the boost board, R44 = R45 = R46 = R47 (named RL)= 750 KOhm; the resistors on the precision rectifier on Dc/DC stage, R65 = R67 = R109 = R112 (named Rb) = 22.1 KOhm, the formula which calculates the voltage on J2.39 is V(J2.39) = (2 / 3.14) * VAC(peak) * Rb / 4RL (see formula (37) in my white paper at page 17); at 300V(RMS), which means VAC(peak) = 424.26 Vpeak and with 750 KOhm and 22.1 KOhm we get V(J2.39) = 1.98968 V, therefore the schematic is correct and @ 2V we should read 300VAC. Maybe when working later on the firmware I changed it into 2.5V --> 300 VAC, so I have to check with my prototype why it is this way. Did you use 4 x 750 KOhm and 22.1 KOhm in your prototype?

    2) Temperature input: you are correct regarding the voltages coming out from LMT87 sense, which are 0.538 V @ 150C and 3.277 V @ -50C. Please consider that on the DC/DC board, at the output of sensor, there is a resistor divider R41 / R103, which reduces the voltage.

    3) The control (reference voltage) for both current and voltage loop is 0-2V, to be applied to pin 5 and 3 of U1, therefore 0-2V means 0-32Vout and 0-60A.

    CAN communication: the uC MSP430F2252 doesn't have CAN hardware nor firmware. As far as I know, more complex system is needed to support CAN, and in my case I just used UART communication, associated to CAN hardware interface, but my software is just a normal duplex serial communication. I suggest to request support for it in separate thread, sorry.

    Please let me know if further support is needed.

    Best regards,

    Roberto

  • 0 in reply to Roberto S.
    Intellectual 255 points

    Dear Roberto,

             Thanks for information. I understand answer 2 & 3.

    Answer 1) Yes I used same resistors in prototype R44 = R45 = R46 = R47 = 750 KOhm & R65 = R67 = R109 = R112 = 22.1 KOhm. But I dont know what went wrong.

    Regarding CAN Communication -: Can you ask internal TI regarding CAN Communication?  

    Thanks & Regards,

    Vijay Shinde.

  • 0 in reply to Vijay Shinde72
    TI__Mastermind 29105 points
    Hey Vijay,

    I see you have a question regarding can in this thread: e2e.ti.com/.../761645

    Please continue the CAN conversation over there.

    Thanks,
    JD

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