HERCULES_SAFETY_MCU_DEMOS: Difference between RM57L843 and TMS570LC4357

Hi Durga Choudhury,

Durga Choudhury said:

1. What are the differences between RM57L843 and TMS570LC4357 (and this can be generalized to the 'RM' family vs 'LC' family). The one I am aware of is the endian-ness (little vs big) but there has to be more.

TMS570 microcontrollers are designed with the capabilities to meet functional safety standard requirements as defined in the ISO 26262 and IEC 61508 standards. RM microcontrollers are designed with capabilities to meet functional safety requirements as defined in IEC 61508.

The main differences between TMS570 and RM microcontrollers are that RM MCUs are Industrial Grade MCUs (not automotive AEC Q100 qualified) and support operation over an ambient temperature range from -40C to 105C (versus -40C to 125C for TMS570).

The main applications of TMS570 are in transportation, for example 

. Braking Systems (ABS and ESC)         • Active Driver Assistance Systems
• Electric Power Steering (EPS)              • Aerospace and Avionics
• HEV and EV Inverter Systems              • Railway Communications
• Battery Management Systems              • Off-road Vehicles

But the RM4x/5x are mainly used in: Industrial Safety Applications and Medical Applications

Durga Choudhury said:

2. The Hercules family uses 'VIM' interrupt controller IP instead of the ARM standard NVIC or GIC. Why is that? What are the advantages and/or differences of VIM over NVIC/GIC?

The Hercules family of controllers uses the Cortex-R4/5 architecture.

The ARM Cortex-R4/5 (ARMv7-R architecture) processor does not support interrupt nesting in hardware, as some Cortex-M (ARMv7-M architecture) processors do. So as this architecture doesn't support interrupt nesting it is simply called as Vectored Interrupt Module (VIM).

Durga Choudhury said:

3. (This is not directly related to the Hercules family but to the dev boards): What are the difference between the DP83640 PHY that appears in the HDK and the DP83630 PHY that appears in the Launchpad? The spec sheets look nearly identical.

The DP83630 is a cost reduced version of the DP83640 that is in a smaller, less expensive package. The DP83630 has the same features and performance as the DP83640.

As the launchpad is designed with small size compared with HDK, so DP83630 is preferred instead of DP83640.

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Thanks & regards,
Jagadish.

Hello Jagadish

Thank you very much for your prompt reply, but I have follow up questions, as follows:

1. "TMS570 microcontrollers are designed with the capabilities to meet functional safety standard requirements as defined in the ISO 26262 and IEC 61508 standards. RM microcontrollers are designed with capabilities to meet functional safety requirements as defined in IEC 61508."

So let me be a bit more specific on this question: what are the software visible differences between the  above two? Are the peripherals, memory map etc identical/substantially similar? Can C code written for one be used unmodified on the other? Can binary code be used, after an endian change, from one to the other?

2. "The ARM Cortex-R4/5 (ARMv7-R architecture) processor does not support interrupt nesting in hardware, as some Cortex-M (ARMv7-M architecture) processors do. So as this architecture doesn't support interrupt nesting it is simply called as Vectored Interrupt Module (VIM)."

This only partially answers my question. ARM must have an interrupt controller IP for this micro-architecture. Why did TI used their own? (This would make code less portable when used on another vendor's Cortex-R5 chip). Is the VIM the same as NVIC with interrupt nesting removed?

3. "The DP83630 is a cost reduced version of the DP83640 that is in a smaller, less expensive package. The DP83630 has the same features and performance as the DP83640."

Well, if DP83630 is *both* cheaper AND smaller than DP83640 but with same feature and performance, then why would anyone want to buy DP83640?