Implementing MRAM Into the Battery Board

[Mikefly123]

Why MRAM?

MRAM or Magnetoresistive Random-Access Memory is a form of non-volatile memory that is more resistant to radiation related errors than more standard forms of flash memory (such as SRAM or DRAM). On our pedigree architecture, the PyCubed, used an Everspin MR25H40 MRAM chip as its primary form of program memory to provide resilience to Total Ionizing Dose (TID) and Single Event Upsets (SEU).

Why Hasn't MRAM Worked Yet?

The original PyCubed architecture boards used the SAMD51 series of microcontrollers that were able to take the MR25H40 chip as a drop in replacement for the a standard flash memory chip thanks to firmware developed by Max Holliday. The key challenge comes from the fact that we use the RP2040 microcontroller rather than the SAMD51. RP2040 does not have native support for MRAM chips, so there is some hacking that has to happen to make this work.

How is This Being Tackled?

There have recently been some promising developments that will allow us to make new versions of firmware that will permit MRAM usage with the RP2040. See the following issue:

raspberrypi/pico-sdk#1714 (comment)