m2 notes

hardware/m2/README.md

@@ -1,7 +1,19 @@
 # Cubo Libre M.2
 
-The SiFive HiFive Unmatched board comes with two M.2 connectors,
+The SiFive HiFive Unmatched board comes with two M.2 connectors.
-as described in the Getting Started Guide:
+
+* Wikipedia M.2:
+https://en.wikipedia.org/wiki/M.2
+
+* `E`: 24-31 pins, 2x PCIe x1, USB 2.0, I2C, SDIO, UART and PCM.
+
+* `M`: 59-66 pins, PCIe x4, SATA and SMBus.
+
+
+Need to determine compatibility for width/length.
+
+
+# Getting Started Guide:
 
 * M.2 E Key Connector for WiFi/Bluetooth.