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MSP430F5328: Analog/Digital Isolation, BSL and pin-to-pin compatibility questions

Darren (FAE)
Expert 5483 points

Part Number: MSP430F5528
Other Parts Discussed in Thread: MSP430F5328,

1) Is TI still planning on producing MSP430F5528 / MSP430F5328 for the foreseeable future?

2) The device has both digital and analog voltage supplies. What are the requirements for dealing with these supplies?
I saw in DS TI recommends connecting them together, and from an E2E post that they are internally decoupled so DVCC variations/noise will have a smaller impact on ADC results. If they are connected together, is the recommendation to use ferrite beads / RC filter to help decouple them from each other?

3) Let's say on the board you want both a UART channel for communication when device is operating, and capability to upgrade firmware via BSL (P1.1 and P1.2). Now let's say you have RS-485 come into the board. Then you use a transceiver to convert that to UART signals. Now we have an Rx and Tx line.
Can you connect that Tx line to both the MSP430 UART Tx pin, and BSL Tx pin? Same with the Rx line?
Or would you need an analog switch or something?

I believe you can tie them together, because BSL would trigger on boot (hardware trigger) and run, before the device does all the peripheral setup. This way, anything coming in on Rx/Tx to the other UART channel doesn't matter. Also, after device initializes and regular program is running, you could jump to BSL address in software, as long as interrupts are disabled first, so no problem here either. Yes?

4) Again for BSL...the MSP430F5528 comes with USB BSL by default. Is the UART BSL code (like for the MSP430F5328) available somewhere, so the customer just needs to flash that into the right memory address themselves? Or do they need to write the code form scratch...?

5) Only differences between MSP430F5528 and MSP430F5328 are that the F5528 has USB, and the F5328 doesn't, right? No other changes to pin layout / electrical characteristics / etc except for USB-related?

  • 0
    TI__Mastermind 49692 points

    Hello,

    It's best to split up questions into multiple threads (within reason) to enable better searchability for the E2E community. Please keep this in mind for future posts.

    1) Yes.

    2) Normally, a low resistance resistor is used between DVCC and AVCC. Each should have decoupling capacitors according to the datasheet. A good reference/example for this would be the schematic for the device-specific target socket board or EVM.

    3) The UART BSL pins can be used for normal serial communication. When the BSL entry sequence is invoked on the appropriate pins, the bootloader mode is entered and the device can be programmed. If whatever is connected to the UART pins can't handle both types of communication, then I would recommend using separate UART modules.

    4)  Refer to the Creating a Custom Flash-Based Bootloader (BSL) app note. Another good BSL resource is the MSP430 Flash Devices Bootloader (BSL) app note.

    5) That seems to be the main difference, but please compare the datasheets to confirm.

  • 0 in reply to James Evans
    TI__Expert 5483 points

    Some follow-up questions related to the above answers. (I changed the post title to "Analog/Digital Isolation, BSL and P2P" for better clarity for now)

    2) From other E2E posts, I saw the recommended resistor is 10~20Ω - is this value accurate?

    5) The customer is considering MSP430F5328 vs MSP430F5528, as it comes w/ UART BSL at factory ship-out and they don't really need USB. I am looking at the DS, but could you confirm my summary?

    - Both devices have 4x timer modules; TAx modules have external input, TBx has external input if mapped to P4 pin
    - Both devices have RTC that can be configured as timer counter, and also a WDT
    - Both devices have ZXH package, and the pin-outs are identical except for A6~A9 and B6~B9 (USB vs non-USB)

    Regards,
    Darren

  • 0 in reply to Darren (FAE)
    TI__Mastermind 49692 points

    2) That's a reasonable range. Obviously, a higher value will drop more voltage for the same amount of current flowing. I would recommend that they measure the voltage drop from DVCC to AVCC at maximum current and make sure the voltage difference doesn't exceed the limit described in the datasheet. For the MSP430F5328, a maximum difference of 0.3 V between AVCC and DVCC can be tolerated during power up and operation.

    5) Correct.

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