MSP430FR2355: ROM Driver

Hi Yutaka,

Great question, and yes, if you are using IAR simulator it will not work.

But first, for other readers of this posting, I'll explain where to find this information.

When you download MSP430WARE, by default it is installed on your PC at C:\ti\msp430ware_3_80_13_03 (this is what I have installed, yours may be different).

Navigate to the directory path C:\ti\msp430ware_3_80_13_03\driverlib\driverlib\MSP430FR2xx_4xx

There you will find the driverlib source files for the MSP430FR2xx_4xx family of MCUs.

Look for the file "rom_map_driverlib.h" This is a listing of all the ROM functions.  Depending on the device, certain functions will be include their ROM while others may not. 

So how do you know which ROM functions are included in each device?  Take a look in the directory path C:\ti\msp430ware_3_80_13_03\driverlib\driverlib\MSP430FR2xx_4xx\rom_headers.  There you will find the rom_driverlib file for the various devices.

The method to access the ROM functions is to use the macros in rom_map_driverlib.h

Let's take a look at the function for enabling ADC interrupts:

#ifdef ROM_ADC_disableInterrupt
#define MAP_ADC_disableInterrupt                                              \
        ROM_ADC_disableInterrupt
#else
#define MAP_ADC_disableInterrupt                                              \
        ADC_disableInterrupt
#endif

Always use the macros starting with MAP_.  The compiler will check if the function exists in the device's ROM table and if so, it will use the ROM_ function call.  If the function is not included for this device, the compiler will choose the standard function that is pulled in from the driverlib source code.

Now, to answer you question specifically about IAR, the linker file (xcl) is selected automatically based on the device you select.

And, if you have added the driverlib directory and its contents to your project, and use a #include <driverlib.h> in the file that uses the ROM function, the compiler will do the rest.

Hi Dennis,

Thank you for your advices.

I have question.

- xcl file

I changed default xcl from my xcl in my embed workspace. I checked the file. But I seem to the xcl file dose not write 20bit rom area address.

Can I use this defaul xcl for the ROM function?

- compiler settings of IAR

My workspace had set code model is large and data model is small. These both have to be large, right?

- ROM image

Please check previous pdf’s page 23 of msp432.

I seem to the file set additional write option for ROM image. I think why msp430fr2355 dose not include the rom image in msp430ware?

With that and the proper xcl, I thought the rom function wouldn't be an address anomaly. Is this correct?
Of course, since I use simulator, it may not work and may get stuck in a waiting function in the rom function.However, I think there are many codes that just only set. Can I get an image from you?
If not, can I do this effort by reading the ROM image from the microcontroller?

- ROM function

Can the ROM function embedded in a microcontroller at the time of manufacture at TI suddenly change? Can my code(old ROM code) end up referring to the address of a different function if I don't realize that you guys changed them?

Best regards

Dennis Lehman
Hi Dennis,

Could you support above my question?

Hi Yutaka,

First let me make sure we are using the same terms here.  ROM is "read only memory" pre-programmed at TI and can never be modified.  FRAM is the memory where you can place your application code and modify if needed.

There is no ROM image provided with MSP430Ware. Your large code and small data memory model is correct.

Next, let me make sure I understand what you are attempting to do ...if you are using a simulator (in other words you are not programming an acutal MSP430), then there is no way to implement any ROM function.  Keep in mind the ROM functions are the exact same driverlib functions you see in the driverlib source files. Since you are not using an actual MCU, you must instead compile and link the driverlib source code files.

You can only use ROM functions if programming/debugging an actual MSP430 MCU.

Regarding a ROM function changing - no way.  ROM is permanent memory that can not be modified.

Yutaka Kawabata said:

Can the ROM function embedded in a microcontroller at the time of manufacture at TI suddenly change? Can my code(old ROM code) end up referring to the address of a different function if I don't realize that you guys changed them?

Looking at driverlib/MSP430FR2xx_4xx/rom_headers/rom_driverlib_fr235x.h the interface to ROM functions is via a lookup table of function pointers.

Where the function pointer to each function is at a fixed address in ROM. At run-time a call to a ROM function reads the function pointer in ROM, which then points at the actual address of the function in ROM.

That allows TI to modify the ROM functions for later silicon revisions in a way that shouldn't break compatibility with existing programs. 

Hi Yutaka,

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Hi Dennis,

If our system does not use DriverLib or FFTLib in this msp430, can we change the code model to small model?
I have tried to using DriverLib, but due to the overhead of calling the ROM function increased ROM area...

Or could I be doing something wrong calling the ROM function?

Hi Yutaka,

Yes, you can switch to small code model.

Regarding a call to a ROM function, I'm not sure why you are seeing a large overhead.  As Chester pointed out, a call to any ROM function is simple using a function pointer defined in rom_driverlib_fr235x.h file, or am I not understanding your question.

I think I'm still not fully understanding what you are attempting.

Let me summarize my thoughts - You can use small code/data model, but you won't be able to call any ROM function.  To use the ROM functions you must use the large code model, but keep in mind it does slightly increase the overall size of your code because the compiler is using 32-bit vs 20-bit addressing. Using a ROM function won't consume any FRAM space because these functions are in ROM.  All that is needed is to include the appropriate header files and call a ROM function, ex - ROM_ADC_getInterruptStatus();