S130 Target Memory Modification

[Wedy Hsiao]

Hi,

Recently, I was trying to established an application based on ble_app_hrs with PCA10028.

The MCU I used is nRF51822_xxac (256KB), S130 for softdevice and the SDK is 12.3.

The original target memory setting is:

IROM1 start 0x0 size 0x40000

IRAM1 start 0x20000000 size 0x8000

Before I add my program in the project the Program Size: Code=29680 RO-data=460 RW-data=444 ZI-data=4932. -> Flash Successfully.

After I programmed my code, the size become like this: Code=42980 RO-data=1804 RW-data=940 ZI-data=7700  -> It will show as below picture

 This hex file has data in SoftDevice region.

Thus, I would like to find someone to guide me how to modified the setting to meet my requirement.

Thanks.

[Edvin]

If you started out with ble_app_hrs, then I suggest that you try to use the memory target settings that come with this example:

What you are currently seeing is that you try to program your application with the flash settings set to the entire flash of the chip, but need to save space for the softdevice in the bottom of the flash. 

The softdevice also requirre some RAM (IRAM1), so set these settings as well. The RAM requirement may change in your application, but it should be printed in the log if you need to adjust it. 

Best regards,

Edvin

[Wedy Hsiao]

May I know how do you estimate this?

[Edvin]

The flash needs to start after the softdevice. The softdevice has a given size. As you can see from your screenshot the softdevice uses 108kB.

108kB = 108Bytes*1024 = (dec)110592 Bytes =  (hex)0x1B000, so you should use that as your ROM1 Start (as in my previous screenshot). The size of the flash on the nRF51 is 0x4 0000. So the size should be 0x40000 - start value, which is 0x25000.

The IRAM1 is a bit more complicated, since it depends on your number of services, characteristics, and number of supported connections. However, this should be written in the log if you need to adjust it. 

[Wedy Hsiao]

Hi Edvin,

Thank you for your further description.

I am confused that "The size of the flash on the nRF51 is 0x4 0000. So the size should be 0x40000 - start value, which is 0x25000."

The size of nRF51 is 256 kB = 256 Bytes*1024= 262144 bytes =0x40000, but why you enter 0x25000 in the blank of size instead of 0x40000. 

Besides, is that means the IRAM need to meet Program Size: Code=42980 RO-data=1804 RW-data=940 ZI-data=7700 ? I was assumed that 0x200003880 is the start address for APP and the end address for softdevice.

May I know where could I check the register address of memory map? And can it be tell by the target setting?

Thanks.

[Edvin]

Wedy Hsiao said:

The size of nRF51 is 256 kB = 256 Bytes*1024= 262144 bytes =0x40000, but why you enter 0x25000 in the blank of size instead of 0x40000. 

 That is because in Keil or any other IDE that you may use, these are the settings for the applicaton. So you tell the IDE what area of the flash that is available. The softdevice uses the flash addresses: 0x00000 to 0x1AFFF, and hence, the application can use the rest: 0x1B000 to 0x40000. This means that the size of the flash available equals 0x40000-0x1B000 = 0x25000. This is the size of the flash that is available for the application. 

 

Wedy Hsiao said:

May I know where could I check the register address of memory map? And can it be tell by the target setting?

 Have you tried monitoring the log?

[Wedy Hsiao]

Hi Edvin,

I am not sure where could I find the log.

I just observed the program size after built project.

Thanks.

[Edvin]

Please see this guide on how to monitor the log:

https://devzone.nordicsemi.com/f/nordic-q-a/16979/where-can-i-see-nrf_log-output

[Wedy Hsiao]

Hi Edvin,

Recently, I also viewed the post, but still get some confused.

https://devzone.nordicsemi.com/nordic/short-range-guides/b/getting-started/posts/adjustment-of-ram-and-flash-memory

After I check the p_app_ramm_start is 0x20003EC8, does it means I should modified the IRAM1 Start from this address?

Besides, I aslo confused the description "that (IRAM1 Size + IRAM1 Start) should not be larger than the size of available RAM", I think only the start address 0x20000000 is already bigger that the chip restriction. And I also curious about that you said the space were reserve for softdevice, why it is not a stable setting as ROM? 

Thanks.