URL:
<http://savannah.nongnu.org/bugs/?34961>
Summary: ATtiny4313 stack is being initialized beyond the
range that is addressable by SP
Project: AVR C Runtime Library
Submitted by: joerg_wunsch
Submitted on: Thu 01 Dec 2011 02:07:32 PM CET
Category: Library
Severity: 3 - Normal
Priority: 5 - Normal
Item Group: Startup code
Status: None
Percent Complete: 0%
Assigned to: None
Open/Closed: Open
Discussion Lock: Any
Release: 1.7.*
Fixed Release: None
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Details:
The ATtiny4313 only offers the SPL register, so the stack pointer
cannot go beyond 0xff. However, the device features twice the
amount of SRAM, compared to the ATtiny2313, so the SRAM range
goes from 0x60 through 0x15F. Consequently, the header file
sets RAMEND to 0x15F, and the startup code attempts to use
this value for the stack pointer. As there is no SPH register,
this effectively results in the stack pointer being initialized
to 0x5F, so the stack is located in the upper IO space.
Suggestion: use a specific symbol _SPINIT in the device header
file, so the startup code can prefer that value over RAMEND
if it is present (and proceed using RAMEND as it used to for
any header file that does not override the _SPINIT value).
That way, only the startup code and the iotn4313.h file need
to be touched. (There appears to be no other device with that
phenomenon.)
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