Update README.md

README.md

@@ -21,7 +21,18 @@ This board comes flashed with a Serial DFU bootloader and it has an onboard USB-
 
 # Custom board with Segger J-Link
 
-<img src='jlink/flashing-bootloader.png' width=50%>
+The Segger J-Link is a very helpful tool, but it's quite expensive.  With it, we can use Nordic's command line utilities, including `nrfjprog`.  I wrote a shell script with three commands to erase, flash the adafruit bootloader, and then start the chip running.  
+
+```
+nrfjprog -f nrf52 --eraseall
+nrfjprog -f nrf52 --program feather52_bootloader_v050_s132_v201.hex
+nrfjprog -f nrf52 --run
+```
+
+<img src='jlink/jlink-wiring.jpg' width=30%>
+<img src='jlink/flashing-bootloader.png' width=30%>
+
+The J-Link requires a wire to ensure the target has power.  In the image above, red is target power (3.3V), black is ground, green is SWDCLK, and blue is SWDIO.
 
 # Custom board with OpenOCD and Raspberry Pi
 
@@ -30,6 +41,6 @@ You don't have to spend hundreds on a J-Link (even though it is very nice).  Usi
 <img src='openocd/bootloader-raspberrypi.jpg' width=53%>
 <img src='openocd/flashing-bootloader.png' width=30%>
 
-Support for the NRF52 is not in the stable release of OpenOCD as of V 0.10, but you can patch it following the instructions on <a href='https://primalcortex.wordpress.com/2017/06/10/setting-up-openocd-for-programming-the-nordic-nrf52832-chip/'>this page</a>.
+Support for the NRF52 is not in the stable release of OpenOCD as of V 0.10, but you can patch it following the instructions on <a href='https://primalcortex.wordpress.com/2017/06/10/setting-up-openocd-for-programming-the-nordic-nrf52832-chip/'>this page</a>.  They worked for me, with the small addition that I needed to eliminate two duplicate variable definitions that broke my build.