add u12

u12.json

@@ -0,0 +1,22 @@
+{
+    "target": "kasli",
+    "min_artiq_version": "6.0",
+    "variant": "u12",
+    "hw_rev": "v2.0",
+    "base": "standalone",
+    "core_addr": "192.168.1.75",
+    "peripherals": [
+        {
+            "type": "grabber",
+            "ports": [0, 1, 2]
+        },
+        {
+            "type": "sampler",
+            "ports": [3, 4]
+        },
+        {
+            "type": "sampler",
+            "ports": [5, 6]
+        }
+   ]
+}