writing odd addresses on msp430f6 famil mcu

baycan vural

Other Parts Discussed in Thread: MSP430F6779

Hi,

Currently I am using msp430f6779 mcu, and I have a variable which resides and odd address (0x4673) on RAM memory. This variable's type is uint16_t. When I try to write that address a value , It writes from 0x4672 address(1 byte previous). Can anyone tell me why I am having this problem and how I can solve?

Thanks

Best Regards

over 10 years ago

0 Anders Lindgren over 10 years ago

Expert 2070 points

When you write in C, a 16 bit variable should never be placed on an odd address, since the hardware doesn't support it.

So, if this is a C variable, you must have done something very special to place it on an odd address -- however, it's hard for us to figure out what that is.

If you have created the variable from assembly, you probably didn't specify alignment requirement. How this is done is tool specific, see your manual for details.

-- Anders Lindgren, IAR Systems

0 baycan vural over 10 years ago in reply to Anders Lindgren

Intellectual 945 points

Yeah I figured it out Andres thank you for your reply.Actually I did something special for solve this. I have casted my variable to uint8_t and then I wrote byte one byte.

0 baycan vural over 10 years ago in reply to baycan vural

Intellectual 945 points

Another thing, Do you know any document about allignment on msp430 mcu. Can you suggest one ?

best regards

0 Anders Lindgren over 10 years ago in reply to baycan vural

Expert 2070 points

It's all in the Users Guide, you can download it from the Ti web site.

To make a long story short. If you access something as a word (a 16 bit value) or "address" (a 20 bit value), the location must be on an even address.

I would not recommend you accessing the individual bytes of the 16 bit variable. Instead, try to figure out why it is placed on an odd address and correct that problem.

-- Anders Lindgren, IAR Systems

0 Clemens Ladisch over 10 years ago in reply to Anders Lindgren

Guru 318740 points

It's all in the Users Guide

Where exactly?

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writing odd addresses on msp430f6 famil mcu