firmware stlink

doc/Nucleo_64.md

-# Nucleo 64
-A collection of documentation, tricks and tips regarding the ST Nucleo 64 development kit.
+# STM32 Nucleo-64 Board
+A collection of documentation, tricks and tips regarding the STM32 Nucleo-64 Board (development kit).
 
-We will mainly cover the `stm32f401re` and `stm32f411re` as these models.
+We will mainly cover the `stm32f401re` and `stm32f411re` as these models (main difference is the higher maximum clock frequency of the `stm32f411re`).
+
+---
+## Stlink inteface
+The nucleo-64 platform has an onboard `stlink-v2.1` SWD interface (programmer) supported by `openocd`. By default the programmer is connected to the target (`stm32f401re` or similar). 
+
+---
+### Programming external targets
+You may use the board as a programmer (connector `CN4` SWD), in that case you should remove the `CN3` jumpers, and optionally desolder `SB15` (SWO) and `SB12` (NRST). See board documentation for details. 
 
 ## Links
+* [Nucleo-64 board](http://www.st.com/content/ccc/resource/technical/document/user_manual/98/2e/fa/4b/e0/82/43/b7/DM00105823.pdf/files/DM00105823.pdf/jcr:content/translations/en.DM00105823.pdf) 
+
+    Board documentation.
+* [Firmware Upgrade](http://www.st.com/en/development-tools/stsw-link007.html)
 
+    Standalone java program.
 # Clocking
 * [Note on Overclocking](https://stm32f4-discovery.net/2014/11/overclock-stm32f4-device-up-to-250mhz/)