writing to Program memory in PIC controllers

On Jan 4, 1:35=A0pm, Chris H <ch...@phaedsys.org> wrote:

> I thought that until some one sent me a link to the case history. =A0Turns=

> out McDonnell's were intentionally running their coffee some 20 degrees
> hotter than anyone else for reasons of storage life when brewed. =A0On a

Tip of the iceberg, as far as lawsuits vs. frivolity go.

BTW that story was always very counter-intuitive to me - I would
expect that increasing the temp would REDUCE the shelf life. Very
strange.

In message 
<d1c3c5ab-85d2-4bf8-b031-7b3ac2fc8b22@f3g2000hsg.googlegroups.com>, 
larwe <zwsdotcom@gmail.com> writes
>On Jan 4, 1:35&#4294967295;pm, Chris H <ch...@phaedsys.org> wrote:
>
>> I thought that until some one sent me a link to the case history. &#4294967295;Turns
>> out McDonnell's were intentionally running their coffee some 20 degrees
>> hotter than anyone else for reasons of storage life when brewed. &#4294967295;On a
>
>Tip of the iceberg, as far as lawsuits vs. frivolity go.

Yes.

>BTW that story was always very counter-intuitive to me - I would
>expect that increasing the temp would REDUCE the shelf life. Very
>strange.

Me too. Never did work it out.
-- 
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
\/\/\/\/\ Chris Hills  Staffs  England     /\/\/\/\/
/\/\/ chris@phaedsys.org      www.phaedsys.org \/\/\
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/

>On Jan 2, 11:23=A0am, "aroravaibhav87" <aroravaibha...@gmail.com> wrote:
>> With reference to the
dochttp://www.avrfreaks.net/index.php?name=3DPNphpBB=
>2&file=3Dviewtopic&t=3D380...
>>
>> ,it's possible to write directly into the program memory section in
AVR
>> controller ,I would like to know whether it is possible to follow a
>> similar kind of procedure for PIC controllers as well.
>
>After looking at the link you posted, it looks to me like you want to
>know how to store C language constants in flash memory? That is, you
>want to compile them into your code, and burn them into the target
>chip at the same time you download your program, right?
>
>That is certainly possible with the PIC24/dsPIC devices. They have a
>special architecture that lets you map the 24-bit program memory bus
>over to the 16-bit data memory bus. I think this is called Program
>Visibility, or something like that. C30 handles that for you
>automatically.
>
>There's actually 2 ways to view program memory as data on that chip
>family. The other is via a special table assembler instruction. C30
>supports both of these, and you don't have to know the underlying
>details.
>
>const char buf[] =3D "abc"; // constant data is stored in flash and
>accessed automatically via Program Visibility (you write zero code)
>
>char buf[] =3D "abc"; // this is an initialized value. It's stored in
>flash and copied to RAM in the startup code. That uses the table
>method internally. This is a little more memory efficient because it
>can use every byte of flash. The Program Visibility method actually
>wastes 1 byte out of every 3 because 24 bits don't map directly to 16
>bits. But Program Visibility lets you directly read flash data at
>runtime without first copying them over to RAM, which is needed with
>non-consts.
>
>My discussion above does NOT tell you how to write to flash memory at
>runtime. This is strictly a discusssion of how to store constants in
>flash at the time you download your program to the chip. Writing to
>flash at runtime is much harder.
>
>Eric
>
>



Thanks for all the info , the two methods that you described work fine ,
but I was actually for a way by which I could store some constants into
the chip independent of the program itself, ie I do not have to write the
data variables in the program itself, but download the variables in the
program flash directly.

>On Jan 2, 11:23=A0am, "aroravaibhav87" <aroravaibha...@gmail.com> wrote:
>> With reference to the
dochttp://www.avrfreaks.net/index.php?name=3DPNphpBB=
>2&file=3Dviewtopic&t=3D380...
>>
>> ,it's possible to write directly into the program memory section in
AVR
>> controller ,I would like to know whether it is possible to follow a
>> similar kind of procedure for PIC controllers as well.
>
>After looking at the link you posted, it looks to me like you want to
>know how to store C language constants in flash memory? That is, you
>want to compile them into your code, and burn them into the target
>chip at the same time you download your program, right?
>
>That is certainly possible with the PIC24/dsPIC devices. They have a
>special architecture that lets you map the 24-bit program memory bus
>over to the 16-bit data memory bus. I think this is called Program
>Visibility, or something like that. C30 handles that for you
>automatically.
>
>There's actually 2 ways to view program memory as data on that chip
>family. The other is via a special table assembler instruction. C30
>supports both of these, and you don't have to know the underlying
>details.
>
>const char buf[] =3D "abc"; // constant data is stored in flash and
>accessed automatically via Program Visibility (you write zero code)
>
>char buf[] =3D "abc"; // this is an initialized value. It's stored in
>flash and copied to RAM in the startup code. That uses the table
>method internally. This is a little more memory efficient because it
>can use every byte of flash. The Program Visibility method actually
>wastes 1 byte out of every 3 because 24 bits don't map directly to 16
>bits. But Program Visibility lets you directly read flash data at
>runtime without first copying them over to RAM, which is needed with
>non-consts.
>
>My discussion above does NOT tell you how to write to flash memory at
>runtime. This is strictly a discusssion of how to store constants in
>flash at the time you download your program to the chip. Writing to
>flash at runtime is much harder.
>
>Eric
>
>



Thanks for all the info , the two methods that you described work fine ,
but I was actually for a way by which I could store some constants into
the chip independent of the program itself, ie I do not have to write the
data variables in the program itself, but download the variables in the
program flash directly.