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MSP430F5419A: MSP430 increased I/Os

Ryan T
Intellectual 2821 points
Part Number: MSP430F5419A

Hi! I'm debating between a few options to gain more I/Os on my MSP430 device. It seems like the MSP430 options with lots of I/O also have much higher amounts of non-volatile memory, which is not necessary for my design and will add to the cost of the device by quite a bit. 

Option 1: Use an I/O expander. I saw this application brief on TI.com for a SPI I/O expander: www.ti.com/.../slaa985.pdf

Option 2: Use another MSP430 device as an I/O expander. While this option would probably be less expensive than an I/O expander, it would be much more involved. I would want to program it from the master device, and haven't found a way to do so without using many pins on the device (needing different pins for programming/controlling application). Is there a resource from TI that mentions using an MSP430 device as an I/O expander for another MSP430 device in a simple way?

Option 3: Purchase the bigger package for more I/O. As mentioned before, I don't think this would be the most cost-efficient option, because of the increased amount of flash. 

I believe option 2 would be the most cost-effective. Is there an option that you would recommend over others?

  • 0
    Guru 35580 points

    As for 2. if you only need 1 wire communication, you can use just the TX side of a UART. If you need 2 way communication you can use a UART with TX and RX or I2C (which will technically allow for any number of MCU/expanders with the same 2 pins.

  • 0
    Guru 33653 points
    Ryan T said:
    Option 2: Use another MSP430 device as an I/O expander. While this option would probably be less expensive than an I/O expander, it would be much more involved. I would want to program it from the master device, and haven't found a way to do so without using many pins on the device (needing different pins for programming/controlling application). Is there a resource from TI that mentions using an MSP430 device as an I/O expander for another MSP430 device in a simple way?

    There is mailbox system in CPUXv2, that can be used for exchange data between master and free running target device over SBW (or JTAG, but it use more pins, and is not option here). In this setup for programming and exchange data only 2 lines between master device (any pins) and target device (TEST and RESET pins) are used. However, software side for this (even fully covered from TI open source) is far from simple.

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