Hi, I using development board "ARM Cortex-M0 STM32F051C8T6 STM32 core board dev. board". i newly started with this, i unable to flash the code...

[Umar]

[TDK]

This board?

http://www.chinalctech.com/cpzx/STM32_Study_Board/356.html

That doesn't have an ST-Link programmer on it. You'll need to get one and connect it appropriately.

Genuine ST Nucleo board are relatively cheap and a lot more user friendly to work with.

[Tesla DeLorean]

Make sure you've connected up the SWD connection to the ST-LINK, along with power.

Make sure you can access the board using the STM32 Cube Programmer tool.

Pick a slower connect speed for CM0(+) devices, should work at a couple of MHz, but not 24 MHz

[Umar]

Yes i am giving separate power supply, i also "cannot able to access the board through program board".

Please explain third point in detail.

[Umar]

Yes, I am using separate ST-Link Programmer.

[TDK]

> Target voltage: 2.56V

Suggests the board doesn't have sufficient power, and/or isn't connected correctly. This board runs on 3.3V.