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Carter Lee
Carter Lee
Associate III
January 2, 2018
Solved

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

  • January 2, 2018
  • 2 replies
  • 7926 views
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

0690X00000609JQQAY.png

The other is

0690X00000609JpQAI.png

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

#cortex-m3 #mdk #keil-mdk5
This topic has been closed for replies.
Best answer by 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.

2 replies

Andrew Neil
Andrew NeilAnswer
Super User
January 2, 2018
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.

A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.
Carter Lee
Carter LeeAuthor
Associate III
January 2, 2018
Posted on January 02, 2018 at 14:58

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

Andrew Neil
Andrew Neil
Super User
January 2, 2018
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

 
A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.
Tesla DeLorean
Tesla DeLorean
Guru
January 2, 2018
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;

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Andrew Neil
Andrew Neil
Super User
January 2, 2018
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 ...

A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.
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