Zephyr and the Memory Footprint: Difference between revisions

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Do you want to use [https://zephyrproject.org/ Zephyr RTOS] on a Microcontroller with only a few bytes of Flash? Let's try it!
Do you want to use [https://zephyrproject.org/ Zephyr RTOS] on a Microcontroller with only a few bytes of Flash? Let's try it!


On the [https://docs.zephyrproject.org/latest/guides/optimizations/footprint.html Optimizing for Footprint] doc site you will find some hints how to reduce the memory footprint. With this I could reduce the kernel to 6872 bytes. Ok, this is just the kernel to have an idea how much flash it needs. You can analyze the memory usage from the rom/ram-report (for more details have a look at the Zephyr [https://docs.zephyrproject.org/latest/guides/optimizations/tools.html Optimization Tools]).
On the [https://docs.zephyrproject.org/latest/guides/optimizations/footprint.html Optimizing for Footprint] doc site you will find some hints how to reduce the memory footprint.  
Ok let's do it. I compiled the following application by using this configs:
{| style="width: 100%;"
| style="width: 50%; vertical-align:top;" |
main.c:
<syntaxhighlight lang="c">
void main (void) {
    uint32_t i = 0;
   
    // run the loop for ever
    while (true) {
        i++;
    }
}
</syntaxhighlight>
| style="width: 50%; vertical-align:top;"|
prj.conf:
<syntaxhighlight lang="c">
# disable all peripherals
CONFIG_GPIO=n
CONFIG_SERIAL=n
CONFIG_SPI=n
CONFIG_I2C=n
 
# disable the boot banner
CONFIG_BOOT_BANNER=n
 
#disable all debug and log messages
CONFIG_DEBUG=n
</syntaxhighlight>
|}
 
 
With this application and settings I could reduce the kernel to 6872 bytes:
 
<syntaxhighlight lang="bash">west build -p auto -b <board name> </syntaxhighlight>


<syntaxhighlight lang="sh">
<syntaxhighlight lang="sh">
Line 9: Line 44:
         IDT_LIST:          56 B        2 KB      2.73%
         IDT_LIST:          56 B        2 KB      2.73%
</syntaxhighlight>
</syntaxhighlight>
Ok, this is just the kernel to have an idea how much flash it needs. You can analyze the memory usage from the rom/ram-report (for more details have a look at the Zephyr [https://docs.zephyrproject.org/latest/guides/optimizations/tools.html Optimization Tools]).
   
   


But how much does a small hello world application need, for example?
But how much does a small hello world application need, for example?

Revision as of 12:09, 26 January 2021

Do you want to use Zephyr RTOS on a Microcontroller with only a few bytes of Flash? Let's try it!

On the Optimizing for Footprint doc site you will find some hints how to reduce the memory footprint. Ok let's do it. I compiled the following application by using this configs:

main.c: 

void main (void) {
    uint32_t i = 0;
    
    // run the loop for ever
    while (true) {
        i++;
    }
}

prj.conf: 

# disable all peripherals
CONFIG_GPIO=n
CONFIG_SERIAL=n
CONFIG_SPI=n
CONFIG_I2C=n

# disable the boot banner
CONFIG_BOOT_BANNER=n

#disable all debug and log messages
CONFIG_DEBUG=n


With this application and settings I could reduce the kernel to 6872 bytes: 

west build -p auto -b <board name>

Memory region         Used Size  Region Size  %age Used
           FLASH:        6872 B        16 KB     41.94%
            SRAM:        1232 B         2 KB     60.16%
        IDT_LIST:          56 B         2 KB      2.73%

Ok, this is just the kernel to have an idea how much flash it needs. You can analyze the memory usage from the rom/ram-report (for more details have a look at the Zephyr Optimization Tools).


But how much does a small hello world application need, for example?

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