I'm working on the iOS app to interact with Arduino boards. On Arduino side i use "transparent" serial implemented in HM-10/11 firmware. So i just wire HM-10/11 RT/TX pins with Arduino ones and it works just perfect and write to specific characteristic to send data and subscribe/read to some specific to read from BLE module. No need to use any SDK or BLE library in arduino sketch, no need to modify bootloader.
Now i need to support NRF51822 BLE chips. Nordic has implemented UART serial in firmware sources but for my NRF51822 board (purchased on ebay) it's not uploaded to the chip by default as i can't see 0001 service and 0002 and 0003 characteristics. Do i need to purchase NRF motherboard and compile and upload this firmware? Can i do it without purchasing this dev kit? Can i upload over USB only or over BLE too?
If your are using NRF51822 standalone module ,then to update its firmware through SWIO/SWCLK pins ,you need a compatible JTAG programmer/debugger (you can check in segger website) . You can use Keil IDE to upload your updated firm ware to the flash memory of NRF51822 .