Hello.
How to use battery Ram in LPC23xx?
How to define and use a simple Array in battery Ram (any example in
Crossworks)?
pozdr
Kuba
[lpc23xx] How to use Battery-RAM?
Started by ●March 31, 2009
Reply by ●March 31, 20092009-03-31
> How to use battery Ram in LPC23xx?
>
> How to define and use a simple Array in battery Ram (any example in
> Crossworks)?
Battery-backed ram is special--it can only be accessed as 16-bit words,
IIRC. You need to read the LPC2k user manual.
--
Paul Curtis, Rowley Associates Ltd http://www.rowley.co.uk
CrossWorks for ARM, MSP430, AVR, MAXQ, and now Cortex-M3 processors
>
> How to define and use a simple Array in battery Ram (any example in
> Crossworks)?
Battery-backed ram is special--it can only be accessed as 16-bit words,
IIRC. You need to read the LPC2k user manual.
--
Paul Curtis, Rowley Associates Ltd http://www.rowley.co.uk
CrossWorks for ARM, MSP430, AVR, MAXQ, and now Cortex-M3 processors
Reply by ●March 31, 20092009-03-31
----Original Message----
From: l...
[mailto:l...] On Behalf Of Jakub
Szumacher Sent: 20 November 2008 18:48 To:
l... Subject: [lpc2000] [lpc23xx] How to
use Battery-RAM?
> Hello.
>
> How to use battery Ram in LPC23xx?
>
> How to define and use a simple Array in battery Ram (any
> example in Crossworks)?
>
You have to define a named area of memory...
The battery ram location and size should be defined in the
LPCxxx_MemoryMap.xml file
E.g. in LPC2478 it is at 0xE0084000
Then in flash_placement.xml you need to name the memory area:
Then you position your variables in the battery ram like this:
unsigned int NVRamInt __attribute__ ((section(".nvrdata")));
--
Tim Mitchell
From: l...
[mailto:l...] On Behalf Of Jakub
Szumacher Sent: 20 November 2008 18:48 To:
l... Subject: [lpc2000] [lpc23xx] How to
use Battery-RAM?
> Hello.
>
> How to use battery Ram in LPC23xx?
>
> How to define and use a simple Array in battery Ram (any
> example in Crossworks)?
>
You have to define a named area of memory...
The battery ram location and size should be defined in the
LPCxxx_MemoryMap.xml file
E.g. in LPC2478 it is at 0xE0084000
Then in flash_placement.xml you need to name the memory area:
Then you position your variables in the battery ram like this:
unsigned int NVRamInt __attribute__ ((section(".nvrdata")));
--
Tim Mitchell
Reply by ●March 31, 20092009-03-31
It can only by accessed as 32-bit words actually.
Regards,
Ivan Amancio
_____
De: Paul Curtis [mailto:p...@rowley.co.uk]
Enviada em: ter-feira, 31 de mar de 2009 12:42
Para: l...
Assunto: RE: [lpc2000] [lpc23xx] How to use Battery-RAM?
> How to use battery Ram in LPC23xx?
>
> How to define and use a simple Array in battery Ram (any example in
> Crossworks)?
Battery-backed ram is special--it can only be accessed as 16-bit words,
IIRC. You need to read the LPC2k user manual.
--
Paul Curtis, Rowley Associates Ltd http://www.rowley.co.uk
CrossWorks for ARM, MSP430, AVR, MAXQ, and now Cortex-M3 processors
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Reply by ●April 24, 20092009-04-24
NVRAM is much like any other type of RAM except that all accesses are in 32-bit
words. So, when reading from it, or if you're dealing with elements exactly
32-bits long (e.g., ints, pointers), then there are no problems, just allocate
the variable so it lands in NVRAM.
When writing values other than those that are 32-bits long (e.g., char array), you need to either pre-pack the data into a 32-bit word then write it, or perform a read-modify-write algorithm. Can't give you the code for Crossworks, but for IAR, first define the memory for NVRAM. Then define your variable;
__no_init unsigned long NVRAM_hostname[HOSTNameLength] @ "NVRAM";
Then build a write-byte function with which you can then write some string-copy routines to use it to modify NVRAM:
void NVRAM_writebyte(unsigned long address, unsigned char data) {
unsigned long oldData;
unsigned long mask;
unsigned long newData;
int shift;
int byte;
// create our shift value - remember this is little endian
byte = (address & 0x03);
shift = (byte << 3);
// word-align our address and ensure it's in NVRAM space
address = (address & 0x000007FC) | 0xE0084000;
// put the new data where it should be in the word
newData = (unsigned long)data << shift;
// create mask pattern to erase the bits we don't want from the read
mask = 0xFF << shift;
// read whole word from NVRAM
oldData = *(unsigned long*)(address);
// mask out the bits we DON'T want
oldData &= ~mask;
// or in the new bits we DO want
oldData |= newData;
// write word to NVRAM
*(unsigned long*)(address) = oldData;
}
-----Original Message-----
From: l... [mailto:l...] On Behalf Of Jakub Szumacher
Sent: Thursday, November 20, 2008 11:48 AM
To: l...
Subject: [lpc2000] [lpc23xx] How to use Battery-RAM?
Hello.
How to use battery Ram in LPC23xx?
How to define and use a simple Array in battery Ram (any example in Crossworks)?
pozdr
Kuba
No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 8.5.287 / Virus Database: 270.12.4/2077 - Release Date: 04/24/09 07:54:00
When writing values other than those that are 32-bits long (e.g., char array), you need to either pre-pack the data into a 32-bit word then write it, or perform a read-modify-write algorithm. Can't give you the code for Crossworks, but for IAR, first define the memory for NVRAM. Then define your variable;
__no_init unsigned long NVRAM_hostname[HOSTNameLength] @ "NVRAM";
Then build a write-byte function with which you can then write some string-copy routines to use it to modify NVRAM:
void NVRAM_writebyte(unsigned long address, unsigned char data) {
unsigned long oldData;
unsigned long mask;
unsigned long newData;
int shift;
int byte;
// create our shift value - remember this is little endian
byte = (address & 0x03);
shift = (byte << 3);
// word-align our address and ensure it's in NVRAM space
address = (address & 0x000007FC) | 0xE0084000;
// put the new data where it should be in the word
newData = (unsigned long)data << shift;
// create mask pattern to erase the bits we don't want from the read
mask = 0xFF << shift;
// read whole word from NVRAM
oldData = *(unsigned long*)(address);
// mask out the bits we DON'T want
oldData &= ~mask;
// or in the new bits we DO want
oldData |= newData;
// write word to NVRAM
*(unsigned long*)(address) = oldData;
}
-----Original Message-----
From: l... [mailto:l...] On Behalf Of Jakub Szumacher
Sent: Thursday, November 20, 2008 11:48 AM
To: l...
Subject: [lpc2000] [lpc23xx] How to use Battery-RAM?
Hello.
How to use battery Ram in LPC23xx?
How to define and use a simple Array in battery Ram (any example in Crossworks)?
pozdr
Kuba
No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 8.5.287 / Virus Database: 270.12.4/2077 - Release Date: 04/24/09 07:54:00
