I am designing a data logging system that uploads its data via 3G.
I'm going to be sampling an I2C sensor at 10Hz, buffering this in local memory (or FRAM), and then dumping the contents of the buffer to an SD card periodically (every few seconds).
Every 15 minutes or so, I want to upload the contents of the file to a web server using a 3G module (Sim5360). I understand that this module can be directly connected to an SD card, and can be instructed to upload files from the SD card. This will take processing effort away from my uC and will increase the upload speed that can be achieved, compared to streaming the data from the uC via the UART.
In order for this to work, both the Sim5360 and the uC need to have access to the SD card, requiring a multi master SPI bus. Is this possible?
As long as both devices have the ability to read and write from the SD card, I can ensure that there are no conflicts by simultaneous attempts to use the resource at the same time.
Please can someone tell me if this is possible and if there is anything special I need to do to make this functional?
Alternatively, if anyone has a better idea on how to achieve this, I'd love to hear it.