diff --git a/quick2wire/board_revision.py b/quick2wire/board_revision.py
index ea5c623..a91069d 100644
--- a/quick2wire/board_revision.py
+++ b/quick2wire/board_revision.py
@@ -1,11 +1,43 @@
+"""
+This function returns 2 for the 40 pin pin-out and 1 for 26 pin. Otherwise it returns 0
+"""
 def revision():
+    pinout1 = ['0002','0003','0004','0005','0006','0007','0008','0009','000d','000e','000f','0011','0014']
+    pinout2 = ['0012','0015','a01041','a21041','a22042','900092','900093','9000C1','a02082','a22082','a020d3']
+    
     try:
         with open('/proc/cpuinfo','r') as f:
             for line in f:
                 if line.startswith('Revision'):
-                    return 1 if line.rstrip()[-1] in ['2','3'] else 2
+                    if line.rstrip()[-4:] in pinout1:
+                        return 1
+                    elif line.rstrip()[-4:] in pinout2:
+                        return 2
+                    elif line.rstrip()[-6:] in pinout2:
+                        return 2
+                    else:
+                        return 0
             else:
                 return 0
     except:
         return 0
 
+"""
+These have i2c-0 as default
+Pi 1 Model B Rev 1                0002
+Pi 1 Model B Rev 1 ECN0001        0003
+Pi 1 Model B Rev 2                0004, 0005, 0006
+Pi 1 Model A                      0007, 0008, 0009
+Pi 1 Model B Rev 2                000d, 000e, 000f
+Pi 1 Compute Module               0011, 0014
+
+These have i2c-1 as default
+Pi 1 Model A+                     0012, 0015
+Pi 2 Model B V1.1                 a01041, a21041
+Pi 2 Model B V1.2                 a22042
+Pi Zero V1.2                      900092
+Pi Zero V1.3                      900093
+Pi Zero W                         9000C1
+Pi 3 Model B                      a02082, a22082
+Pi 3 Model B+                     a020d3
+"""