I want to flash nrf51 firmware from another MCU which is connected to nrf51 with UART interface.
I have seen dual bank serial bootloader examples, in that firmware is flashed over uart by using utility tools...
I need this to be happen from MCU connected to nrf51, which will receive binary for nrf51 also and then it should be able to flash that in nrf51.
So is your question just "Is it possible to flash firmware to nRF5x chips from another MCu over UART?" - which obvious answer is YES - or you are asking "will someone do this for me"? If you have serial bootloader which supports UART then you should just use the bootloading protocol to start the procedure, transport the binary and kick start the actual FW swap.
Thanks @endnode, and yes I was seeking for the more details, where can i get the details about Nrf51's booatloading protocol, to initiate update from another MCU (may be ESP8266)
That depends on where you got the bootloader;) The generic one from Nordic nRF5 SDK? Which exact version and source code files you use?
Ever heard about Nordic Infocenter? Here is part with bootloader examples, there should be all you need.
I am using nRF5_SDK_11.0.0. The examples on serial bootloader in SDK uses ZIP files and python script (nrfutil) to flash firmware over uart