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MSP430FR2355: Cross-Chip Interconnection of analog ports

Massa1
Expert 1050 points
Part Number: MSP430FR2355

Hi, all;

The cross-chip interconnection of MSP430FR2355 is very complicated(Data Sheet 6.10.17).

Are analog ports always connected as Figure 6-3?

Please teach me how to use the connections.

Can I read the output voltage of OA0 thru channel 1 of ADC without any wireing?

Can I read the value of VREF+ thru channel 7 of ADC without any wireing when EXTREFEN=1?

B.R.

Massa.

  • 0
    TI__Expert 7365 points

    Hi Massa,

    Fig 6-3 shows the full-featured view. You only need to connect what is required for your application.

    Massa1 said:
    Please teach me how to use the connections.

    The App Note How to Use the Smart Analog Combo in MSP430™ MCUs (Rev. A) has more information on using Smart Analog Combo (SAC). Section 2 has information on the different operating modes while section 3 has information on the interconnection configuration.

    Massa1 said:
    Can I read the output voltage of OA0 thru channel 1 of ADC without any wireing?

    I don't think this is feasible. They are independent peripherals and not connected internally. You will have to wire them externally.

    Massa1 said:
    Can I read the value of VREF+ thru channel 7 of ADC without any wireing when EXTREFEN=1?

    This should be available without any wiring. You can look at section 6.10.1 Power Management Module (PMM) and On-Chip Reference Voltages of the datasheet (www.ti.com/.../msp430fr2355), sections 1.12.4.3 ADC Pin Enable and 1.2-V Reference Settings & section 2.2.8 Shared Reference Generation and Distribution of the Family User's Guide (www.ti.com/.../slau445) for more information on this.

    Srinivas

  • 0
    Guru 88550 points

    > Can I read the output voltage of OA0 thru channel 1 of ADC without any wireing?

    I hesitate to disagree wiith Srinivas, but I'm pretty sure you can -- indeed, this is an intentional feature.

    If you have a Launchpad, you can demonstrate this with its light sensor using msp430fr235x_SAC_L3_06.c:

    http://dev.ti.com/tirex/explore/node?node=AK6ZWSA8R1sxWtrY6VvbVg__IOGqZri__LATEST

    with one change: Replace the line:

    >  SAC2OA = NMUXEN + PMUXEN + PSEL_0 + NSEL_1;//Select positive and negative pin input

    with

    >  SAC2OA = NMUXEN + PMUXEN + PSEL_0 + NSEL_0;//Select positive and negative pin input

  • 0 in reply to Bruce McKenney47378
    Expert 1050 points

    Thanks for Srinivas and Bruce.

    I understand this is complicated issue, because the cross-chip interconnection is special future at MSP430FR2355.

    In old MSP430, almost modules are independent and have no interconnection.

    But obviously Figure 6-3 of MSP430FR2355 Datasheet shows the output of SAC0 OA is connected to P1.1/A1.

    Fortunately, I have a MSP430FR2355 Launch Pad.

    I'll confirm the interconnection of OA and ADC.

    B. R.

    Massa.

  • 0 in reply to Massa1
    Expert 1050 points

    I had an experimet using Launch Pad to confirm the Cross-Chip Interconnection of MSP430FR2355.

    At first, I changed an example msp430fr235x_adc12_02.c to work on Launch Pad.

    Then I marged msp430fr235x_SAC_L3_02.c to the ADC source to evaluate Unity Gain Buufer Mode.

    I connect a variable voltage power supply to P1.3, a voltmeter to P1.1 and execute the program.

    Using CCS Debugger, I can confirm the input voltage reading ADCMEM0 register.

    I can get the right digital values corresponded to the supplied voltages.

    > Can I read the output voltage of OA0 thru channel 1 of ADC without any wireing?

    Answer: Yes.  Refer to Figure 6-3 Cross-Chip Interconnection in Datasheet.

    B.R.

    Massa.

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