What is the difference off-chip and on-chip?

[Carter Lee]

Posted on January 02, 2018 at 14:24

Hi.

I'm confused that KEIL MDK has 2 options as the below,

One is off-chip

The other is

I'm confused that what is the difference between Off-chip and On-chip?

#cortex-m3 #mdk #keil-mdk5

[Andrew Neil]

Posted on January 02, 2018 at 14:34

'On-Chip' means literally what it says - the memory is on the chip!

to spell it out, the memory is integrated onto the same chip - ie, the same piece of silicon - as the CPU and its peripherals.

So, conversely, 'Off Chip' means that the memory is not on the same chip as the CPU. Thus the memory is external to the IC.

[Carter Lee]

Posted on January 02, 2018 at 14:58

Thanks Could you let me know what is the No Init check box?

[Andrew Neil]

Posted on January 02, 2018 at 15:10

Have you tried pressing the 'Help' button?

See also: 

http://www.keil.com/support/man/docs/uv4/uv4_dg_adstarg.htm

 

[Tesla DeLorean]

Posted on January 02, 2018 at 16:01

It allows different memory regions to be defined, these may be physically non-contiguous, and of varying access speed.

NO INIT - Doesn't initialize, don't use for variables you expect to have initial content, ie float pi = 3.14f;

[Andrew Neil]

Posted on January 02, 2018 at 18:26

Clive One wrote:

NO INIT ... don't use for variables you expect to have initial content, ie float pi = 3.14f;

Also means that statics without initialisation won't be zeroed.

This is useful if you want data to survive a reset; eg, if you have some sort of 'non-volatile' RAM ...