Diff: ODBII.cpp

Revision:

0:bb9076ae4c4a

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ODBII.cpp	Wed Jan 27 17:40:51 2016 +0000
@@ -0,0 +1,73 @@
+#include "ODBII.h"
+#include "globals.h"
+
+DigitalOut myled(LED1);//diagnostic LED, used to see if data is being transmitted
+Timer CANTimer;//This is used to determine whether or not the car has taken too long to respond
+
+void set_frequency(int amount)
+{
+    can2.frequency(amount);//Different ECU's operate at different frequencies, 125kbs, 25kbs, 500kbs
+}
+
+float request(char pid)
+{
+    char can_msg[8];//message to be send to CAN 
+    float engine_data = 0;// this is what we get back
+
+
+    //forming the CAN message payload, uses 8 bytes, first is number of extra bytes, second is mode, third is PID, others are misc
+    can_msg[0] = 0x02;//# of extra bytes
+    can_msg[1] = 0x01;//mode
+    can_msg[2] = pid;
+    can_msg[3] = 0;
+    can_msg[4] = 0;
+    can_msg[5] = 0;
+    can_msg[6] = 0;
+    can_msg[7] = 0;
+    
+    if (can2.write(CANMessage(PID_REQUEST, can_msg, 8))) 
+    {
+        myled = !myled;//diagnostic LED
+    }
+    CANTimer.reset();
+    CANTimer.start();
+
+    while(CANTimer.read_us() < 200)//give it some time to respond
+    {
+        if (can2.read(can_MsgRx)) {//if you can read back, then go into it
+            pc.printf("Message read\n\r");
+            
+ 
+            for (int i = 0; i < (int)can_MsgRx.len; i++) {
+                pc.printf("can_MsgRx.data[%d]: %x\n\r", i, can_MsgRx.data[i]);//this just prints the contents of the data back
+            }
+
+
+
+            if ((can_MsgRx.id == PID_REPLY) && (can_MsgRx.data[2] == pid)) //if the PID match, then we know we have valid data
+            {
+                pc.printf("We've made it this far\n\r");
+                switch (can_MsgRx.data[2]) //the PID is in [2], so we use that in this switch
+                { 
+                    case ENGINE_RPM:              //   ((A*256)+B)/4 is the formula for rpm
+                        engine_data =  ((can_MsgRx.data[3]*256) + can_MsgRx.data[4])/4;
+                        break;
+
+                    case ENGINE_COOLANT_TEMP: //C, this is the formula for temp
+                        engine_data =  can_MsgRx.data[3] - 40;
+                        break;
+
+                    case VEHICLE_SPEED:   //[km], this is the formula for kmph
+                        engine_data =  can_MsgRx.data[3];
+                        break;
+                }
+
+                return engine_data;//whatever we get we return back to the main.cpp
+
+            }
+
+        }
+    }
+
+    return 0;
+}
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