As you might have noticed, we have been working on integrating S110/S130 compatibility into BLE API for nRF51 targets. A final tweak is pending in the Nordic stack driver's develop branch, so this support may be available in next version of the API.
(However, you can already try it with the temporary "MCU_NORDIC_16K_S110" flag, cf. step 3 below)
nRF51 SoftDevice differences
As a reminder, the SoftDevice is the firmware shipped with each application. It provides a low-level API over Bluetooth and other capabilities of the chip.
Those are the major differences between the S110 version 8.0.0 and S130 version 1.0.0, for a 128k flash/16k RAM chip:
| S110 | S130 |
|---|
| Available memory for application: |
|---|
| Flash start | 0x18000 | 0x1c000 |
| Flash size | 32k | 16k |
| RAM start | 0x20002000 | 0x20002800 |
| RAM size | 8k | 6k |
| Supported features: |
|---|
| Peripheral (server) | yes | yes |
| Central (client) | no | yes |
As you can see, S130 provides the ability to act both as a central and peripheral simultaneously. It will be able to advertise and scan for other devices. But this comes with a great price, since applications will have 2k less RAM to play with.
Switching to S110
Currently, the live IDE is only able to build S130 applications. Using S110 is possible, but will require to get your hands dirty and do a local build. I'm using HeartRate with GCC as an example. To do this, you'll need a GCC toolchain, and srecord.
First, export your program to "GCC (ARM Embedded)".
Then, to check you have all the required tools, type make, followed by make merge. This should end with something like:
arm-none-eabi-size BLE_HeartRate.elf
text data bss dec hex filename
24004 128 1640 25772 64ac BLE_HeartRate.elf
srec_cat mbed/TARGET_NRF51822/TARGET_NORDIC/TARGET_MCU_NRF51822/Lib/s130_nrf51822_1_0_0/s130_nrf51_1.0.0_softdevice.hex -intel BLE_HeartRate.hex -intel -o combined.hex -intel --line-length=44
Beware, Windows users!
If you're using a case-insensitive file system (e.g. FAT), you might encounter obscure errors, because of a conflict between ./nRF51822/source/nordic-sdk/components/softdevice/s130/include/ble.h and ./BLE_API/ble/BLE.h.
This will also be fixed when moving to yotta. The simplest solution I can see now, is removing -I./BLE_API/ble from INCLUDE_PATHS line in the Makefile. With this, BLE.h will only be accessible with #include "ble/BLE.h", which is already the conventional way to include it.
1. Change the linker script
The linker script specifies the layout of the final image. It is located in mbed/TARGET_NRF51822/TOOLCHAIN_GCC_ARM/NRF51822.ld
What we're interested in is the memory section. This is the one for a 128K/16K chip:
MEMORY
{
FLASH (rx) : ORIGIN = 0x0001C000, LENGTH = 0x24000
RAM (rwx) : ORIGIN = 0x20002800, LENGTH = 0x1800
}
You will want the following layout (see the above table for explanations):
MEMORY
{
FLASH (rx) : ORIGIN = 0x00018000, LENGTH = 0x28000
RAM (rwx) : ORIGIN = 0x20002000, LENGTH = 0x2000
}
With armcc, this file is called "nRF51822.sct" for "scatter file" and has a different format, but serves the same purpose.
2. Change the SoftDevice
Change this line:
SOFTDEVICE = mbed/TARGET_NRF51822/TARGET_NORDIC/TARGET_MCU_NRF51822/Lib/s130_nrf51822_1_0_0/s130_nrf51_1.0.0_softdevice.hex
with that one:
SOFTDEVICE = mbed/TARGET_NRF51822/TARGET_NORDIC/TARGET_MCU_NRF51822/Lib/s110_nrf51822_8_0_0/s110_nrf51822_8.0.0_softdevice.hex
3. Disable GattClient
That's the simplest part! Just add the following symbol to your build (CC_SYMBOLS): -DMCU_NRF51_16K_S110.
After a make clean all merge, you should see something like this:
arm-none-eabi-size BLE_HeartRate.elf
text data bss dec hex filename
21500 128 1296 22924 598c BLE_HeartRate.elf
srec_cat mbed/TARGET_NRF51822/TARGET_NORDIC/TARGET_MCU_NRF51822/Lib/s110_nrf51822_8_0_0/s110_nrf51822_8.0.0_softdevice.hex -intel BLE_HeartRate.hex -intel -o combined.hex -intel --line-length=44
^
Now using S110 SD ----------------------------------------------------'
Also notice that we now have 16 + 2k more flash, and 2000 + 344 more bytes of RAM :)
As you might have noticed, we have been working on integrating S110/S130 compatibility into BLE API for nRF51 targets. A final tweak is pending in the Nordic stack driver's develop branch, so this support may be available in next version of the API. (However, you can already try it with the temporary "MCU_NORDIC_16K_S110" flag, cf. step 3 below)
nRF51 SoftDevice differences
As a reminder, the SoftDevice is the firmware shipped with each application. It provides a low-level API over Bluetooth and other capabilities of the chip. Those are the major differences between the S110 version 8.0.0 and S130 version 1.0.0, for a 128k flash/16k RAM chip:
As you can see, S130 provides the ability to act both as a central and peripheral simultaneously. It will be able to advertise and scan for other devices. But this comes with a great price, since applications will have 2k less RAM to play with.
Switching to S110
Currently, the live IDE is only able to build S130 applications. Using S110 is possible, but will require to get your hands dirty and do a local build. I'm using HeartRate with GCC as an example. To do this, you'll need a GCC toolchain, and srecord.
First, export your program to "GCC (ARM Embedded)". Then, to check you have all the required tools, type
make, followed bymake merge. This should end with something like:Beware, Windows users!
If you're using a case-insensitive file system (e.g. FAT), you might encounter obscure errors, because of a conflict between
./nRF51822/source/nordic-sdk/components/softdevice/s130/include/ble.hand./BLE_API/ble/BLE.h. This will also be fixed when moving to yotta. The simplest solution I can see now, is removing-I./BLE_API/blefrom INCLUDE_PATHS line in the Makefile. With this, BLE.h will only be accessible with #include "ble/BLE.h", which is already the conventional way to include it.1. Change the linker script
The linker script specifies the layout of the final image. It is located in
mbed/TARGET_NRF51822/TOOLCHAIN_GCC_ARM/NRF51822.ldWhat we're interested in is the memory section. This is the one for a 128K/16K chip:MEMORY { FLASH (rx) : ORIGIN = 0x0001C000, LENGTH = 0x24000 RAM (rwx) : ORIGIN = 0x20002800, LENGTH = 0x1800 }You will want the following layout (see the above table for explanations):
MEMORY { FLASH (rx) : ORIGIN = 0x00018000, LENGTH = 0x28000 RAM (rwx) : ORIGIN = 0x20002000, LENGTH = 0x2000 }With armcc, this file is called "nRF51822.sct" for "scatter file" and has a different format, but serves the same purpose.
2. Change the SoftDevice
Change this line:
with that one:
3. Disable GattClient
That's the simplest part! Just add the following symbol to your build (CC_SYMBOLS):
-DMCU_NRF51_16K_S110.After a
make clean all merge, you should see something like this:arm-none-eabi-size BLE_HeartRate.elf text data bss dec hex filename 21500 128 1296 22924 598c BLE_HeartRate.elf srec_cat mbed/TARGET_NRF51822/TARGET_NORDIC/TARGET_MCU_NRF51822/Lib/s110_nrf51822_8_0_0/s110_nrf51822_8.0.0_softdevice.hex -intel BLE_HeartRate.hex -intel -o combined.hex -intel --line-length=44 ^ Now using S110 SD ----------------------------------------------------'Also notice that we now have 16 + 2k more flash, and 2000 + 344 more bytes of RAM :)