Hi Friends, greetings of the day...
I am new to this Arm community and very beginner to work on Arm cortex...
I am doing some investigation on a multi-core processor.
1. Can some one please tell me what is the power consumption of arm cortex A5 core ?
There is a default core from which i am going to enable A5 core and measure the current.
2. Should there be any change in the power consumption, if A5 is operating at different clock rates?
Hope my question is clear and sorry if there is any mistake : )
Please reply... Thanks
Hello, ARM develops the architecture and licenses it to other companies, therefore power consumption of particular processor depends on implementation of processor core design.
Find out who produces your ARM Cortex A5 processor and get its datasheet with information about power consumption.
I give you example of two processors with the same core design but different implementations:
1) NXP i.MX 6 Series Applications Processors with ARM Cortex A9 core;
2) Texas Instruments Sitara AM4x Processors with ARM Cortex A9 core.
Hi Vanhealsing, Thanks for the reply.
1. I am using HALO mac57d5xx from NXP. I have checked the datasheet of this chip but i dont see anything related to
the power consumption of A5 core...
2. And i don't understand why memcpy function is taking more time when executed in A5 core which is running at
higher frequency (320Mhz) compared to M4 core running at lower frequency (160 Mhz)... Could you please comment on this Vanhealsing.
I tried with lower frequency for A5 core too, but the result was same....
Thanks in advance.
1. If datasheet doesn't provide information about power consumption try to look other infrormation (for example documentation like application notes) about low power modes of a particular processor. Usually producers of such System-on-Chips describe power consumption of chips in defferent power modes.
2. First, these cores Cortex A5 and Cortex M4 are different in their nature, because designed for different goals:
processor with Cortex A5 core is an application processor with a pipeline of 8-stages,
Cortex M4 is a core for microcontrollers and it has pipeline of 3 stages,
Cortex M4 usually programmed by Thumb instructions wich is smaller in size than ARM instructions of Cortex A5,
Cortex M4 operates on physical memory addresses,
Cortex A5 operates on virtual memory addresses which includes translation phases of Memory Management Unit (but you can configure to disable MMU and work with physical addresses as well, but without operating system),
Cortex M4 microcontrollers might not have cache,
Cortex A5 usually have L1 and L2 caches.
Second, memcpy function implements copy operation, therefore you have to understand from what source you read and where you write (for example read from internal SRAM and write to external DRAM).
The same code can be executed from different memory regions with different speed of execution.
Thanks Again Vanhealsing.
I tried different regions for executing memcpy.
For example copy 1kb byte from Internal SRAM to Internal SRAM, Internal flash to Internal SRAM etc.. I ran application
for both cores M4 and A5 individually and as i said in all scenario's memcpy in M4 is executing faster than A5.
A5 is operating @320Mhz and M4 is operating @ 160Mhz.
I was thinking that core running at higher frequency should be performing faster, but that is not what i am observing.
What could be the possible explanation for this.
Thanks Van for spending your valuable time and information.
Core running at higher frequency does not mean executing code at higher frequency because of slow memory core may stuck in pipeline stall waiting for data load or data store to complete.
Cortex M4 have higher density code because of Thumb instructions.
Cortex M4 ICode and DCode buses allow core to perform faster code execution (instruction and data can be loaded in 1 cycle).
Try to use for long copy operations DMA controller in the SoC with Cortex A5 core and compare performance.
This is the first time i registered for some community for getting help and happy to see people like you spare time to help someone in need...
I truly Appreciate that.
" Kindness is Free, sprinkle that stuff everywhere".