MPC5642A External SRAM

[salmanc]

Hi,

I want to expand #MPC5642A microcontroller's memory and use an external SRAM. Is that possible? If it's possible, can I run the code through this external memory? Or can I only store variables, calibration data etc. ? 

Thanks in advance.. 

[salmanc]

Thank you, I get it. 

Can't we use Calibration bus interface instead?

We were using MPC5644A for years, then we needed more. But stocks of the MPC5644A are limited and we have to change the microcontroller unfortunately. Total memory of the MPC5642A is not enough for us, so we are looking for some solution..  What would you recommend? 

[davidtosenovjan]

Calibration bus is only present with special calibration package (biggest package which is not offered to mass market) and its purpose is basically only development so it cannot be used.

In your case I could recommend to use external SPI SRAM, but don't expect code execution from that memory, only data access over standard SPI communication protocol.

Or use some similar device. Suitable devices could be MPC5674F, MPC5676R or never MPC5777C or MPC5775B/E.

[salmanc]

Can I ask why it's not offered to mass market? I searched these special calibration packages called "VertiCal Calibration System" and in the link below, it says "It consists of an SRAM memory chip and a VertiCal interface adapter on the secondary side." So can we say it's a way to add external SRAM Memory to system?

And by saying "its purpose is only development" why can't we use it like other memories such as SRAM or NOR Flash? 

https://www.nxp.com/design/development-boards/automotive-development-platforms/mpc56xx-mcu-platforms... 

By the way thank you so much, we will definitely consider similar / suitable devices for our project.

[davidtosenovjan · Accepted solution]

Because the special package you can only find installed within "VertiCal Calibration System". These devices are manufactured with very little volume. You cannot expect to order thousands MCUs of this package.

It is mainly used by automotive customers (powertrain type market - engine or transmission control) emulating using of internal FLASH by external SRAM with VertiCal solution. They call it calibration - lot of data tables are used (by default stored in internal flash) and during runtime address pointers can be switched (by MMU) to external SRAM allowing to tune/optimize their configuration on the fly without a need to re-program the flash. That's intented use.

[salmanc]

Thank you so much for all your answers.

That really helped us.

[davidtosenovjan]

Hi, unfortunately not, this device does not have external bus. I would recommend to use MPC5644A.