Hi guys

Just an simple question, say I have a constant

char str[] = "HELLO";

In a 8-bit MCU, it will take 6 bytes flash memory. Now my question is, how many bytes will it take in a 16-bit/32-bit MCU. Will that take 12 bytes flash memory in a 16-bit MCU and 32 bytes flash memory in a 32-bit MCU? Or does it still take only 6 bytes?

I mainly use 8-bit MCU, but there is a project that I will need to use 16-bit MCU, and it looks like the flash memory in a 16-bit MCU is used up a lot faster for some simple code.

Thanks guys!

 

It will depend on the MCU and maybe even the compiler but each character should take 8bits or 1 byte. You really should check your specific documentation to be sure. That is way it was written.

 

It will take 6 bytes.
Modern 16-bit and 32-bit MCUs will pack bytes as required into multi-byte memory locations.

 

It will depend on the MCU and maybe even the compiler but each character should take 8bits or 1 byte. You really should check your specific documentation to be sure. That is way it was written.

Any pointer on which section should I be looking at? The flash and memory section? Compiler? The 16-bit MCUs I am talking about are MSP430 and the 32-bit MCUs are PIC32MM.

 

It will take 6 bytes.
Modern 16-bit and 32-bit MCUs will pack bytes as required into multi-byte memory locations.

That's good to know, how about memory use? I assume it will be packed bytes as required?

You mentioned multi-byte memory locations. Are you referring to a special memory location that you can pack bytes, or just a general memory location that everyone can use?

 

That's good to know, how about memory use? I assume it will be packed bytes as required?

You mentioned multi-byte memory locations. Are you referring to a special memory location that you can pack bytes, or just a general memory location that everyone can use?

By multi-byte, I mean if memory is organized as 16-bit words, you get two bytes packed into one word.

MSP430 may be a 16-bit processor but memory is still organized in 8-bit locations. There is nothing special for you to worry about.
Generally, constant bytes are stored in CODE space, i.e. in FLASH memory.

 

By multi-byte, I mean if memory is organized as 16-bit words, you get two bytes packed into one word.

MSP430 may be a 16-bit processor but memory is still organized in 8-bit locations. There is nothing special for you to worry about.
Generally, constant bytes are stored in CODE space, i.e. in FLASH memory.

Thanks for the quick reply, appreciated it!