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How do I go about picking an architecture ? My first thoughts suggested Cortex M3 but the more I look into it the less sure I am.
Obviously I don't to go to the trouble of learning a new technology only to find that I've made a bad processor choice (ie nearly end of line). I've spent many hours looking at many websites and have yet to find any high-level stuff on choosing my first ARM device.
If there's one thing wrong with ARM its the almost infinite number of devices
I'm an embedded developer wanting to undertake my first ARM project, so I'm completely new to the ARM architecture. I want a low power device with serial, USB and some ADC channels.
Tapeer.
i am sad for u. do u know u r repeating ur self?
ur recovery has not started yet?
Always yo're freind.
Zeusti.
(knows you do not need to push r0 and r1)
lobotomized.
i enjoy so much all the philisofical discusions with u. but i am busy and must work now.
plz. u lie down and relaxxxxx.
(job one, write good delay rootine)
I don't bother to read you messages anymore. I will only stop after you openly admit that you went through the lobotomy procedure, like this: "My name is zupeesti and I am lobotomized. Excuse my bad manners" (you can add typos were you like).
tamir, you sound like you have an anger mgmt issue.
calm down, please.
NO WAY, YOU @#!$#$%$@^#$%$#%$@%@%$@
:-)
"But such facts don't mean all OEM libraries are bad, or all programmers are bad, or all people are bad."
No one has made such a claim.
The question is just how much you are willing to trust the library supplier if you don't have access to the source code to verify the code quality and to incorporate fixes. Incorporating a bad library in a product can be lethal for a company, so the question is how much trust you have in the library supplier.
just a little foot note: you do know that this only applies to THUMB mode, don't you? otherwise, the following would not have appeared in the ATPCS (ARM-Thumb Procedure Call Standard) document, surely you agree?
maybe you have skipped this while browsing your documentation:
infocenter.arm.com/.../DUI0056.pdf
see page 24, paragraph 2.2.1
quote:
The following register usage applies in all variants of the ATPCS except where otherwise stated. To comply with the ATPCS you must follow these rules: Use registers r0-r3 to pass parameter values into routines, and to pass result values out. You can refer to r0-r3 as a1-a4 to make this usage apparent. See Parameter passing on page 2-9. Between subroutine calls you can use r0-r3 for any purpose. A called routine does not have to restore r0-r3 before returning. A calling routine must preserve the contents of r0-r3 if it needs them again....
however, if you can find a similar quote for ARM mode, in which I have written my code - you are right (but I doubt you will).
I forgot to highlight the following:
"A called routine does not have to restore r0-r3 before returning". but this is only true when complying with ATPCS. it is certainly not true (as far as I know) when running in ARM mode.
i dn'nt have time 2 teech u simple basics. but u need advising.
read
en.wikipedia.org/.../Calling_convention
look at entry for arm
infocenter.arm.com/.../IHI0042C_aapcs.pdf
look at page 16
if u do not understand now. compile this little function with keil
void SmallDelay(void) { volatile int x; for (x=10000;x!=0;--x) ; }
look at the code made by compiler
SmallDelay PROC ;;;783 ;;;784 void SmallDelay(void) 000ba4 e59f0100 LDR r0,|L1.3244| |L1.2984| ;;;785 { ;;;786 volatile int x; ;;;787 ;;;788 for (x=10000;x!=0;--x) 000ba8 e2500001 SUBS r0,r0,#1 000bac 1afffffd BNE |L1.2984| ;;;789 ; ;;;790 } 000bb0 e12fff1e BX lr ;;;791 ENDP
see that r0 is not preserved.
or do you think keil have got it wrong?
as i say b4. you should not say book is bad if you have not seen.
not surprisingly you don't answer my question, but let correct you: R0 is not saved because it should not - it is always used as a return value. try to actually understand what you are posting, for a change.
look man, I'm serious now. you are a danger to society. do you understand? you are dangerous by writing delay loops like that. confide it: you are indeed dangerous. don't write software for: planes missile space systems cars trains etc.
stick to flashing LEDs and bad English, please...
I wonder: can you point to anywhere in the document (that you obviously did not read at all!) to prove that I'm wrong? here, I challenge you: take your time, and tell all of us a page number and paragraph number. I'm waiting, "correcting professor".
a nother example to cklarimfy.
void SmallLoop(void) { volatile int a; for (a=10000;a!=0;--a) { volatile int b; for (b=10000;b!=0;--b) { volatile int c; for (c=10000;c!=0;--c) { ; } } } }
SmallLoop PROC ;;;783 ;;;784 void SmallLoop(void) 000ba4 e59f211c LDR r2,|L1.3272| ;;;785 { ;;;786 volatile int a; ;;;787 ;;;788 for (a=10000;a!=0;--a) 000ba8 e1a03002 MOV r3,r2 |L1.2988| ;;;789 { ;;;790 volatile int b; ;;;791 ;;;792 for (b=10000;b!=0;--b) 000bac e1a01003 MOV r1,r3 |L1.2992| ;;;793 { ;;;794 volatile int c; ;;;795 ;;;796 for (c=10000;c!=0;--c) 000bb0 e1a00003 MOV r0,r3 |L1.2996| 000bb4 e2500001 SUBS r0,r0,#1 000bb8 1afffffd BNE |L1.2996| 000bbc e2511001 SUBS r1,r1,#1 ;792 000bc0 1afffffa BNE |L1.2992| 000bc4 e2522001 SUBS r2,r2,#1 ;788 000bc8 1afffff7 BNE |L1.2988| ;;;797 { ;;;798 ; ;;;799 } ;;;800 } ;;;801 } ;;;802 } 000bcc e12fff1e BX lr ;;;803 ENDP
are r0 r1 r2 r3 all return values? have keil got big code problems? no!
plz wake up and read.
you see, I have provided a quote which makes you look bad because you made a totally unfounded, repeated and fantastic claim that is (as far as I can tell; if somebody knows better please do correct me and justify the "professor"!) wrong. you showed a piece of assembly that further proves that you don't understand the problem at hand. I am still waiting. show me a quote or a piece of code that proves you point; show me that apart from register R1 to R4 in thumb mode, a program does not need to preserve the processor context (unless the register is shadowed by the mode itself, or course!!!!). I'm still waiting.
are you sure this code is compiled at ARM mode?