ecu_reader.cpp

00001 #include "mbed.h"
00002 #include "ecu_reader.h"
00003 #include "globals.h"
00004 
00005 
00006 // Use a timer to see if things take too long
00007 Timer CANTimer;  
00008 namespace mbed { 
00009 
00010 
00011 ecu_reader::ecu_reader(int can_speed)
00012 {
00013     can2.frequency(can_speed);
00014 }
00015 
00016 //#define TIMEOUT 200
00017 unsigned char ecu_reader::request(unsigned char pid,  char *buffer)
00018 {
00019     char can_msg[8];
00020     float engine_data;
00021         
00022     led1 = 1;
00023   
00024     can_msg[0] = 0x02;  
00025     can_msg[1] = 0x01;
00026     can_msg[2] = pid;  
00027     can_msg[3] = 0;
00028     can_msg[4] = 0;  
00029     can_msg[5] = 0;
00030     can_msg[6] = 0;  
00031     can_msg[7] = 0;
00032 
00033    if (can2.write(CANMessage(PID_REQUEST, can_msg, 8))) {
00034          
00035     }
00036    
00037    led1 = 0;
00038    CANTimer.reset();
00039    CANTimer.start();
00040    
00041    while(CANTimer.read_ms() < TIMEOUT) {
00042    
00043    if (can2.read(can_MsgRx)) {
00044                
00045         if((can_MsgRx.id == PID_REPLY) && (can_MsgRx.data[2] == pid))
00046         { 
00047                         switch(can_MsgRx.data[2])
00048                         {   /* Details from http://en.wikipedia.org/wiki/OBD-II_PIDs */
00049                             case ENGINE_RPM:              //   ((A*256)+B)/4    [RPM]
00050                                 engine_data =  ((can_MsgRx.data[3]*256) + can_MsgRx.data[4])/4;
00051                                 sprintf(buffer,"%d rpm ",(int) engine_data);
00052                                 break;
00053                             
00054                             case ENGINE_COOLANT_TEMP:     //     A-40              [degree C]
00055                                 engine_data =  can_MsgRx.data[3] - 40;
00056                                 sprintf(buffer,"%d degC ",(int) engine_data);
00057                             
00058                             break;
00059                             
00060                             case VEHICLE_SPEED:         // A                  [km]
00061                                 engine_data =  can_MsgRx.data[3];
00062                                 sprintf(buffer,"%d km ",(int) engine_data);
00063                             
00064                             break;
00065 
00066                             case MAF_SENSOR:               // ((256*A)+B) / 100  [g/s]
00067                                 engine_data =  ((can_MsgRx.data[3]*256) + can_MsgRx.data[4])/100;
00068                                 sprintf(buffer,"%d g/s",(int) engine_data);
00069                             
00070                             break;
00071 
00072                             case O2_VOLTAGE:            // A * 0.005   (B-128) * 100/128 (if B==0xFF, sensor is not used in trim calc)
00073                                 engine_data = can_MsgRx.data[3]*0.005;
00074                                 sprintf(buffer,"%d v ",(int) engine_data);
00075      
00076                             case THROTTLE:            //
00077                                 engine_data = (can_MsgRx.data[3]*100)/255;
00078                                 sprintf(buffer,"%d %% ",(int) engine_data);
00079                              
00080                             
00081                             break;
00082                         }
00083         
00084                 return 1;
00085         
00086          }
00087 
00088    }
00089    }
00090 
00091      return 0;
00092   
00093 
00094 
00095 
00096 }
00097 } // namespace mbed