56800E Linker Command file for 56F8367 question

[bdang]

Tool: Codewarrior tool for DSC56800/E version 8.3 build 091203

target: 56F8367 processor

I'm having issue of string constant. The code below to initialize a Global char array does not work (the array elements have wrong data when later being read out as ex: serial_dr = String[0] does not TX out ascii H correctly) :

char String[] = "Hello";      // defined as global variable

However, when assigning the array individually in main(), as below, it works (serial_dr=String[1] does send out 'e' ascii)

String[0]='H';

String[1]='e';

String[2]='l';

String[3]='l';

String[4]='o';

String[5]='\0';

I looked into the Linker command file trying to understand how the tool writing the "Hello" string into the array. Does the tool write the string "Hello" into p_flash_ROM_data(RX) (which is located in the program flash memory block as the executable code), and then when the code runs after power reset, the code copies the string from p_flash into the array String[] (in internal RAM)?

(It seems the p_flash_ROM_data section is located right after the executing code section. How does the tool know if the p_flash_ROM_data does not written over the chip's p_flash ROM total area with a very large string constant for example?)

MEMORY
{
.p_interrupts_ROM (RX) : ORIGIN = 0x0000, LENGTH = 0x00AC # reserved for interrupts
.p_flash_ROM (RX) : ORIGIN = 0x00AC, LENGTH = 0x3FF54 # 256K words contiguous flash minus interrupt space

# p_flash_ROM_data mirrors internal xRAM, mapping to origin and length
# the "X" flag in "RX" tells the debugger to download to p-memory.
# the download to p-memory is directed to the address determined by AT
# in the section definition below.

.p_flash_ROM_data (RX) : ORIGIN = 0x0001, LENGTH = 0x3FFF # internal xRAM mirror

.p_boot_flash_ROM (RX) : ORIGIN = 0x40000, LENGTH = 0x4000 # 16K words
# .p_reserved : ORIGIN = 0x44000, LENGTH = 0xB800 # 46K words
.p_internal_RAM (RWX) : ORIGIN = 0x4F800, LENGTH = 0x0800 # 2K words
.p_external_RAM (RWX) : ORIGIN = 0x50000, LENGTH = 0x0000 # max available
.x_internal_RAM (RW) : ORIGIN = 0x0001, LENGTH = 0x3FFF
.x_flash_ROM (RW) : ORIGIN = 0x4000, LENGTH = 0x4000
.x_external_RAM (RW) : ORIGIN = 0x8000, LENGTH = 0x7000
.x_onchip_peripherals (RW) : ORIGIN = 0xF000, LENGTH = 0x1000
.x_external_RAM_2 (RW) : ORIGIN = 0x10000, LENGTH = 0xFEFF00
.x_EOnCE (RW) : ORIGIN = 0xFFFF00, LENGTH = 0x0000
}

Thank you,

Brian

Sorry that I posted this earlier on Classic/legacy, but think that site does not get the same exposure as this site. 

[bdang]

Hi Jennie,

Sorry that I was tied up with other projects until recently. I looked into your sample project after linking, and found the two const arrays were placed in the  .x_RAM   section, instead of pflash ROM section. Why would one waste RAM space for const instead of using code flash ROM? The target is a 56F8367 processor with plenty of space for code memory. How would you do to assign these const (and any string constants such as in error_message="Motor is overheated!") to Code flash rom memory?

const int table[5] = {0,1,2,3,4};
const int test[5] = {3, 4, 5,6,7};

Best,

Brian

[ZhangJennie]

Hi Brain.

see this demo code *.cmd file, const data is defined in x_RAM. thus string "table" and "test" are allocated in x_RAM.

in your application, if you don't want const code allocation in x_RAM, please set it to the PFLASH or other ROM section that you want. This can distribute const data to ROM

Have a great day,
Jennie Zhang

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[ZhangJennie]

Good! Thanks for the sharing.

Best Regards,

Jennie Zhang.

[bdang]

Hi Jennie,

I followed this instruction found on the old post of Fiona Kuang, and I was able to open your sample project:

"2) Or in your CW go to File->Import project Browse for the project location and set the "objects of" field to "All Files" Select the *.mcp file and click open Now in the window "Name new project as:" you should name your project and select Save. By doing any of the above you should be able to open your project."

Thanks,

Brian

[ZhangJennie]

Hi Brain.

Thank you for contacting us.

The attached project is a small example for place data at a specific address.

Can you please refer this demo to develop yours.

Have a great day,
Jennie Zhang

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[bdang]

Hi Jennie,

Thank you for the sample project but for some reasons when open the project *.mcp file, it didn't open properly. See below. What did I do wrong?

Thanks,

Brian

[ZhangJennie]

HI Brain.

Please open IDE menu "Edit" "preference", check "use text-based projects". then restart Codewarrior. import the demo project. it should work.

Have a great day,
Jennie Zhang

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[bdang]

Hi Jennie,

I checked "Use Text based project" as instructed, then clicked on the project file *.mcp, but still had the same problem of opening the project. Might be I didn't read you correctly. You said "then restart Codewarrior. import the demo project. it should work." 

You wrote "import the demo project" and so I also tried "File" , "Import Project", but there is no *.xml file to open.

I'm lost here.

Brian