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    What is the reasoning behind the BMI270 requiring an 8KB upload with every powerup?

    What is the reasoning behind the BMI270 requiring an 8KB upload with every powerup?

    Established Member

    We're a big user of the BMI160, having chosen it after discovering our previous ST MEMS chip proved too unworkable and unreliable.

    Now Bosch is suggesting the BMI270 "for new designs" instead of the BMI160. It's pin and package compatible, which is a good start.

    However, the BMI270 requires an 8KB download on every powerup. What is the reasoning there? In an embedded environment you may only have 32KB or 64KB of nonvolatile memory space in the MCU. Demanding that we give up 8KB of that precious memory space is asking  a LOT. We cannot afford an extra, external, SPI interfaced memory device just to reprogram the MEMS chip every time... that turns the great, wonderful BMI160 single chip solution into an awkward, expensive, real-estate-consumptive two chip "solution".

    Furthermore, many embedded environments (such as ours) cannot be reflashed or updated after manufacture. If there's no way to externally update the 8KB file, what's the point? It's just an extra step that consumes 8KB of memory space, plus the extra firmware to do the work, plus the time loss at powerup, to repeat the exact same procedure every time power is applied.

    The 8KB file is downloaded from github so it's not changing. It's the same file for every device so it's not calibration data (which would be device or wafer specific). Why not make this reflashable within the BMI270 and put the default, then-current file in memory at the factory? Then build-and-ship users like us could use it in its default condition, while accessible designs could reflash it later if necessary/desired.

    We got to the BMI160 because our previous choice didn't work well. Looks like we might be forced to go elsewhere, again, if the BM160 goes out of production (after just two years!?!) and the BMI270 is the "recommended replacement".

    Downloading  8KB of fixed data into the chip with every powerup is an unrealistic burden for many small/embedded designs. There must be one heck of an awesome benefit to offset all of the overhead. Anyone know what it is?


    10 REPLIES 10

    Established Member

    (You asked me this via Private Message too, and I sent you the following reply there too.)

    Hello, we are located in the United States. The application is sensors for the marine industry, installed on watercraft to indicate X/Y/Z orientation and rotation. Two years ago we selected your BMI160 over the ST LSM6DS3 due to reliability issues suffered by the latter device. We felt confident in choosing the BMI160 because it was a newer device so we felt that it would safely stay in production for quite some time.

    But now Bosch is recommending the BMI270 for new designs, suggesting that the BMI160 may be retired. In looking at the BMI270 it requires an 8KB upload every time it powers up (!?!). This is ridiculous in a microcontroller environment where nonvolatile memory is already at a premium. Most of the MCU's we use have just 32KB-64KB of nonvolatile memory in the first place, so 8KB represents a huge percentage of available space. That's just wasteful.

    Furthermore, it's the same 8KB every single time. Obviously it cannot be "updated" in an embedded environment in the field, so that 8KB will never change. Therefore the "ability" to upload its 8MB image at every powerup delivers zero functionality. It's nothing but overhead which wastes nonvolatile memory and time at bootup.

    A much more logical approach would be to program the default 8KB into the BMI270 at the factory, so it can be used in its default configuration with zero powerup programming. If some design(s) require a different 8KB, they are the exception and can treat it as such without burdening every single BMI270 design with this overhead.

    As it stands now, the BMI270 is simply off the list. We cannot consider it for new designs. If the BMI160 goes out of production, we will be forced to choose a different part - likely from a different manufacturer - and redesign our printed circuit board to support the new part.

    Community Moderator
    Community Moderator

    Hello IDEngineer,

    We clarify with you that bmi160 has no plans to stop production. Please do not convey misleading information. If anyone tells you that BMI 160 is going to stop production, please tell us know who said that. If people who are not Bosch say that the bmi160 is out of production, he is making a rumor.
    BMI270 has more powerful functions with abundant features, these features didn't need MCU to participate in the algorithm operation, also help whole system to save power consumption. If you don't use these BMI270 features, you could use BMI270 minimal config file to reduce the occupation of host Flash size. Don't think that BMI270 only supports 8KB config file, OK?
    You located in the United States, which distributor you approached? Please approach loacal distributor first for your product design if you have no distributor.

    Established Member

    I appreciate your reassurance that the BMI160 is remaining in production. However, it is easy to understand why so many of your distributors have told us that the BMI160 is ending production. As just a few examples:

    * Your own webpage for the BMI160 at contains the following banner: "For new designs we recommend to use BMI270". Statements like that are very commonly used to provide guidance that the part in question is nearing end of life.

    * At the bottom of that same Bosch webpage, under "Order", literall y every one of your authorized distributors shows "Out of stock". This includes Autronix, Arrow, DigiKey, Future, and Mouser.

    * Above this list of authorized distributors there is the following line: "For new designs we recommend to use BMI270."

    * We have talked to several of your authorized distributors and none expect to receive any BMI160's from Bosch for several months, if they have any sort of delivery date at all. They refer us to your website's repeated statements of "For new designs we recommend to use BMI270" and have suggested that this indicates the BMI160 will be discontinued.

    It's not surprising that, given all of the above, people in your distribution network (including distributors all the way to customers like us) would get the impression that the BMI160 was being discontinued. I'm happy to hear that's not the case.

    To reassure everyone in the distribution network, please reply here with Bosch's current lifetime projection for the BMI160. In other words, what is the minimum amount of time looking forward that the BMI160 will continue to be produced? Or, said a different way, what is the earliest date that Bosch would discontinue production of the BMI160?

    Thank you for helping to eliminate the confusion surrounding this issue.

    Community Moderator
    Community Moderator

    Hello IDEngineer,,

    "so many of your distributors have told us that the BMI160 is ending production." Why don't you give out detailed distributor information?

    This is a platform for technical exchange. No one is allowed to spread rumors maliciously here.

    "For new designs we recommend to use BMI270", it is a guggestion.

    We clarify with you twice that bmi160 has no plans to stop production. It has no plan to stop production. How can I tell you when to stop production?

    Established Member

    >>This is a platform for technical exchange. No one is allowed to spread rumors maliciously here.<<

    No one is spreading rumors, malicious or otherwise. For review, here are my statements in the above messages: "Bosch is recommending the BMI270 for new designs, suggesting that the BMI160 may be retired", "If  the BMI160 goes out of production", "I appreciate your reassurance that the BMI160 is remaining in production" (emphasis added).

    I fully explained why it could be interpreted that the BMI160 was being retired. You confirmed it remains in production, and I thanked you for that reassurance. No rumors, just questions and answers. And continued availability of a part is critical to design decisions so this topic is well suited for this forum.

    >>bmi160 has no plans to stop production. It has no plan to stop production. How can I tell you when to stop production?<<

    Let me ask in a different way. Most companies have schedules for how long they expect to be in production for a given part. This allows their various departments to plan accordingly. As the end date nears, they start publishing "Not for Future Design" or "Recommended Alternative Parts" or similar statements so that customers can adjust their own plans. Even if you don't have a specific retirement date, it's likely you have "minimum 12 months" or "minimum 30 months" or similar so that your own departments know how to plan. It would be nice if you would share that "minimum window" so that others who see the "For new designs we recommend to use BMI270" on the BMI160 webpage don't get the same wrong impression we did.

    Again, thank you for helping to resolve this misunderstanding. I look forward to whatever "minimum window" information you choose to share here with parties interested in the BMI160.