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STM8 port: Update README with new RAM layout details.

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Kelvin Lawson
2010-03-09 00:58:36 +00:00
parent 7d56170c40
commit 8d3a0fc4db
1 changed files with 2 additions and 23 deletions
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ports/stm8/README
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@@ -371,31 +371,10 @@ The application's data starts at the bottom of RAM, and this includes all
of the thread stacks which are statically allocated arrays. The idle
thread, main thread, and automated test thread stacks are allocated here.
If your application includes a large amount of data which is nearing the
top of RAM, then you must be careful that conflicts do not occur with the
startup stack. The startup stack uses the 64 bytes from RAMTOP down. This
is not reserved with the linker, so you will receive no warning if your
own data encroaches on this area. It may not matter because the startup
stack is only used before the OS is started, but if the data here cannot
be corrupted before the OS is started then you should make other
arrangements, such as moving the startup stack elsewhere or placing data
which can be overwritten in this area. To check whether your application
data overlaps with the startup stack you can view the MAP file for the
application. This shows how much RAM is used by the data and BSS areas.
If you have 2048 bytes RAM, then you will need to ensure that the
application data uses less than (2048-64) bytes, or be sure that it is
safe to utilise that area for the startup stack before the OS is started.
The default layout provided with Atomthreads matches the STM8S-Discovery
with 2KB RAM. The linker file reserves the first 0x500 bytes for data
with 2KB RAM. The linker file reserves the first 0x7C0 bytes for data
areas. The region from here up to the end of RAM (0x800) is used for the
the 64 byte startup stack and any other data you require. You may wish
to place some of your thread's stacks in the area above 0x500, or you may
prefer to increase the size of the data area beyond 0x500. A simple
layout would be to allow everything up to (RAMTOP-64) to be used for
application data, leaving the top 64 bytes for use by the startup stack.
This way the linker would warn you if your application data overlapped
with the startup stack.
the 64 byte startup stack.
As mentioned previously, this RAM layout is only the one utilised by the
test applications. You may choose whatever layout you like.