Re: RTOS for ARM Cortex M1

Good for you. I am using 600K A3 and 32Mx32 SDRAM

that no OS will run on this core. I also found that Actel has ported a v3, = which does support OS extensions, to their SmartFusion line. --which I cann= ot use because it is not rad-tolerant. So now, I'm trying to get them to po= rt their v3 core to the ProASIC3 3M part. No word yet on if or when they wi= ll fix this.

ere is a way around the issue (other than having actel fix the IP core)?

Yes, license the source and patch it.

The link

said it all:

1) 2 stacks pointer (leaving only 1 stack pointer). 2) The SVC assembler instruction for software interrupts (protected/ user mode). 3) System timers - for systick?> 1) & 2) stops you from having supervisor mode. 3) can probably be work around with additional resources to implement a timer.

' that no OS will run on this core. I also found that Actel has ported a = v3, which does support OS extensions, to their SmartFusion line. --which = I cannot use because it is not rad-tolerant. So now, I'm trying to get th= em to port their v3 core to the ProASIC3 3M part. No word yet on if or wh= en they will fix this.=20

there is a way around the issue (other than having actel fix the IP core)= ?=20

You can run an RTOS on small 8 bit devices, that definitely don't have the undefined 'OS extensions'. All you need is to find an OS that has been ported, or pay somebody to port it for you.

Some CPU's have additional features that assist in the writing of an RTOS, some are just CPU's. You can run an RTOS on both, one will just be easier to write than the other. FreeRTOS runs on 25 different cores (thats cores as in architectures, not devices), believe me they don't all have OS extensions.

Regards, Richard.

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' that no OS will run on this core. I also found that Actel has ported a v3= , which does support OS extensions, to their SmartFusion line. --which I ca= nnot use because it is not rad-tolerant. So now, I'm trying to get them to = port their v3 core to the ProASIC3 3M part. No word yet on if or when they = will fix this.

there is a way around the issue (other than having actel fix the IP core)?

They should have said no protected mode OSs.

ProASIC3 with M1 soft core is for smaller devices.

SmartFusion with Cortex M3 hard core is for bigger devices and bigger OSs.

that no OS will run on this core. I also found that Actel has ported a v3, = which does support OS extensions, to their SmartFusion line. --which I cann= ot use because it is not rad-tolerant. So now, I'm trying to get them to po= rt their v3 core to the ProASIC3 3M part. No word yet on if or when they wi= ll fix this.

ere is a way around the issue (other than having actel fix the IP core)?

of either a free or commerical RTOS that supports ARM Co=3D

cc=3D

io=3D

Check out Segger embOS. Should do what you want.

An Schwob

This is not a bug that can be fixed, it is an implementation option of the processor core that Actel apparently chose to disable. The OS extensions in C-M1 are not essential to execute an OS on this CPU, but they can help implementing one.

The OS extension comprises of:

1. A second stack pointer to implement two separate stacks for tasks and OS

1. The SysTick timer which serves as a global time base for scheduler.

2. The SVC/PendSV exceptions to request OS services.

Best regards

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No. It means no user mode. By default the CM1 runs in a supervisor alike mode.

An RTOS does not need supervisor/user mode to allow writing safe software. It is a matter of clean design (=> direct message passing).

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42Bastian
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It seems that for a clean context switch, the Cortex m needs a software interrupt (be it then called a supervisor call or something else).

The ARM7TDMI method of switching via PSW to IRQ or SVC mode is not available in Cortex.

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Tauno Voipio
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