Linker script BLE stack for NRF51802

[Harshit]

What will be correct linker script changes for nrf51802 device using soft device ble application 

I made changes in RAM start and SIZE. found in open source forum, 

 MEMORY
{
    FLASH (rx) : ORIGIN = 0x1b000, LENGTH = 0x25000
    RAM (rwx) : ORIGIN = 0x20001fe8, LENGTH = 0x2018
}

and it is working but I don't understand why LENGTH = 0x2018 (8K) working and If I provide higher than this value it doesn't work  as RAM size of nrf51802 is 16KB

Thanks

[Sigurd]

Hi,

0x1fe8 is the amount of RAM allocated/reserved for the SoftDevice. The rest(0x2018) is available for the application. 0x1fe8+0x2018=0x4000 (16K)

[Harshit]

Thanks Sigurd,

So in nrf51802 max RAM size in linker space, I can set to 0x2018?
and where exactly 0x1fe8 size is defined?

[Sigurd]

Harshit said:

So in nrf51802 max RAM size in linker space, I can set to 0x2018?

It depends on how much RAM the softdevice needs. If softdevice uses 0x1fe8, then the app can use 0x4000(RAM in nRF51802) - 0x1fe8 = 0x2018.

Harshit said:

and where exactly 0x1fe8 size is defined?

This number depends on how you configure the SoftDevice. Configuring e.g. more characteristics and services, the SoftDevice will require more RAM. The exact number is returned by the function sd_ble_enable(), and if it needs to be adjusted, it’s printed in the softdevice_enable() function in softdevice_handler.c (SDK 12.3)