2 Replies Latest reply on Feb 15, 2016 12:08 AM by nasac_2167841

    Extending OTA to update additional MCU via PUART

      Hi,

      i'm planning on adding a second MCU (stm32) to a pcb, in addition to the BCM20737s, probably connected via PUART or alternatively, SPI.

      I really like the OTA feature of the Broadcom modules, and would like to extend the feature to be able to update the STM32's firmware as well as the BCM's. I'm sure I'm not the only one with this in mind, and I was wondering if anyone has already extended the OTA feature for this purpose, or if someone would like to offer some thoughts on this?

      Would there be enough space on the internal eeprom of the BCM20737S to copy a complete firmware image before sending it to the STM32? or would it make more sense to pass it through directly?

       

      I was thinking of just joining the two hex files but adding a large offset to the addresses of the STM32's firmware, so that when the BCM receives it, it will be easy to differentiate that from the firmware that's meant for the BCM, (and pass it on to the STM after subtracting the offset on the fly). Is this how you would go about it?

       

      Thanks for any advice (or sample code for that matter ;-)

        • 1. Re: Extending OTA to update additional MCU via PUART

          While the actual details depends on which external STM you are planning to use, I doubt you will be able to fit the entire image to either SRAM or EEPROM before sending it over to the STM.

           

          So you will have to send portions of this over to the STM via SRAM buffers

           

          I would think that writing a custom app would be better than leveraging the OTA scheme as-is since you probably want more fine-grained control over what gets sent to the external MCU and not just overwrite the entire Flash image. But if that is what you want to do, then using appropriate file-offsets as you have suggested would work.

          • 2. Re: Extending OTA to update additional MCU via PUART

            BTW - we do have customers doing exactly what you are attempting to do, but usually they write a custom framework for this purpose that relies on the OTA scheme in the lower levels but still does separate out the two images