From 9565c64a06b7302cd820214f58ea0970d4f1e07a Mon Sep 17 00:00:00 2001
From: travisutk <travisutk@12e2690d-a6be-4b82-a7b7-67c4a43b65c8>
Date: Wed, 15 Aug 2012 22:52:49 +0000
Subject: [PATCH] MCP2515 can now loopback packets!

git-svn-id: https://svn.code.sf.net/p/goodfet/code/trunk@1231 12e2690d-a6be-4b82-a7b7-67c4a43b65c8
---
 client/GoodFETMCPCAN.py | 18 +++++++++++++++---
 client/goodfet.mcpcan   | 14 +++++++++++++-
 2 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/client/GoodFETMCPCAN.py b/client/GoodFETMCPCAN.py
index 4270b20..d4dc159 100644
--- a/client/GoodFETMCPCAN.py
+++ b/client/GoodFETMCPCAN.py
@@ -23,7 +23,9 @@ class GoodFETMCPCAN(GoodFETSPI):
         """Sets up the ports."""
         self.SPIsetup();
         self.MCPreset(); #Reset the chip.
-        self.MCPreqstatLoopback();
+        
+        #Loopback mode for testing.
+        self.MCPreqstatConfiguration();
     def MCPreset(self):
         """Reset the MCP2515 chip."""
         self.SPItrans([0xC0]);
@@ -88,18 +90,28 @@ class GoodFETMCPCAN(GoodFETSPI):
                        0x00, 0x00, 0x00, 0x00
                        ]);
         return data[1:len(data)];
+    def writetxbuffer(self,packet,packbuf=0):
+        """Writes the transmit buffer."""
+        self.SPItrans([0x40|(packbuf<<1)]+packet);
+        
     def rxpacket(self):
         """Reads the next incoming packet from either buffer.
         Returns None immediately if no packet is waiting."""
         status=self.MCPrxstatus()&0xC0;
         if status&0x40:
             #Buffer 0 has higher priority.
-            return self.rxbuffer(0);
+            return self.readrxbuffer(0);
         elif status&0x80:
             #Buffer 1 has lower priority.
-            return self.rxbuffer(1);
+            return self.readrxbuffer(1);
         else:
             return None;
+    def txpacket(self,packet):
+        """Transmits a packet through one of the outbound buffers.
+        As usual, the packet should begin with SIDH.
+        For now, only TXB0 is supported."""
+        self.writetxbuffer(packet,0);
+        self.MCPrts(TXB0=True);
     def packet2str(self,packet):
         """Converts a packet from the internal format to a string."""
         toprint="";
diff --git a/client/goodfet.mcpcan b/client/goodfet.mcpcan
index 99620a3..9de2cc7 100755
--- a/client/goodfet.mcpcan
+++ b/client/goodfet.mcpcan
@@ -53,12 +53,24 @@ if(sys.argv[1]=="sniff"):
 if(sys.argv[1]=="test"):
     print "MCP2515 Self Test:";
     
+    #Switch to config mode and try to rewrite TEC.
+    client.MCPreqstatConfiguration();
     client.poke8(0x00,0xde);
     if client.peek8(0x00)!=0xde:
         print "ERROR: Poke to TEC failed.";
     else:
         print "SUCCESS: Register read/write.";
-
+    
+    #Switch to Loopback mode and try to catch our own packet.
+    client.MCPreqstatLoopback();
+    client.txpacket([0xb1, 0x6b, 0x00, 0x65,
+                     0xb1, 0x6b, 0x00, 0x65
+                     ]);
+    print "Waiting on loopback packet.";
+    packet=None;
+    while packet==None:
+        packet=client.rxpacket();
+    print "Success!  Got %s" % client.packet2str(packet);
 if(sys.argv[1]=="peek"):
     start=0x0000;
     if(len(sys.argv)>2):
-- 
2.20.1