Update README.md

atc/hua-e3372h_320/README.md

@@ -1,3 +1,19 @@
-#Huawei E3372h-320
+# Huawei E3372h-320 modem
 
-https://forum.openwrt.org/t/huawei-e3372h-320-in-ncm-mode/126018/12
+Use usb-modeswitch to switch to NCM mode.
+You need to add a new message and change device entry of 12d1:1f01.
+Thanks to woec at OpenWrt forum, https://forum.openwrt.org/t/huawei-e3372h-320-in-ncm-mode/126018/12
+
+Add mmessage `"55534243123456780000000000000011063000000000010000000000000000"` at the end of the message block, in the begining of `/etc/usb-mode.json`.
+Modify device entry 12d1:1f01 to:
+```
+"12d1:1f01": {
+                         "*": {
+                                 "t_vendor": 4817,
+                                 "t_product": [ 5339, 5340 ],
+                                 "mode": "HuaweiAlt",
+                                 "msg": [  xx ]
+                    }
+             }
+```
+Where xx is the message entry of the newly added message. Verify with `jsonfilter -i /etc/usb-mode.json -e '@["messages"][xx]'`. In my case xx = 61.