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Hi,
I am using AT89C51rd2. When I use big arrays like abc[270] and def[274] in my code, nothing works correct. But i use abc[40] and def[40], every thing is ok.
when abc[270] and def[274] declared, keil generates:
Program Size: data=109.1 xdata=1159 code=12696
when abc[40] and def[40] declared, keil generates:
Program Size: data=109.1 xdata=695 code=12461
In options, "use on-chip xram" is checked. I tried to set AUXR resiter in firmware like XRS0=0,XRS1=0,XRS2=1 to select "software selectable" xram size as 1792. Nothing is work....
What can be the problem???
Thanks...
Many are afraid of touching startup.a51 however in some cases it is MANDATORY. when the OP followed my suggestion (set AUXR in startup) everything worked. thus ANYTHING related to xdata configuration (e.g. SILabs) MUST be done at the beginning of startup if you have an external XDATA memory, you may need to configure the clock at the beginning of startup. if you have a crossbar (SILabs, some ARMs, ,,,) you need to configure it at the beginning of startup.
Generally: anything that relates to XDATA access MUST be done at the beginning of startup this can be memory configuration, memory timing, crossbar, ....
HAVE NO FEAR modifying startup is quite simple. DO NOT call a C routine, C is not "ready"
Erik
I wonder if they are actually afraid, or if they just don't think about it and/or don't realise that it's there?
http://www.keil.com/support/man/docs/c51/c51_ap_customfiles.htm
I guess it's more like an automatic "place all initialization at top of main" which, for some NON-51 compilers (e.g. visual C) may be totally relevant.
There are some 'typical' 'mistakes' 99% of PC coders make when they try to be '51 programmers.
PS I have found "place all initialization at top of main" not to work for IAR/STM32 cortex so it's not just the '51. OK this is a Keil forum, but I work with the tools my customer gives me. Sone the issue is in the ST provided code I believe that the same holds true for Keil ARM