MP3Car.com - View Single Post - OBDII / Elm MPG meter. Almost working but not quite!

god_of_cpu · 09-10-2004, 09:25 AM

This is the exposed interface of the dll, most of these should be semi-self explainatory, but they are explained completely in the code files I'll post later.

This code is in C++, you will have to covert the prototypes to VB.

Code:

INIT_DLL_FUNCTION(LPVOID, WINAPI, API_OBDII_Create,(HWND hWnd, IUnknown* lpUknown));
INIT_DLL_FUNCTION(BOOL, WINAPI, API_OBDII_Release,(LPVOID lpUser));

INIT_DLL_FUNCTION_NAMED(VOID, WINAPI, GetModuleName,(CHAR* szName, INT iMaxLen), API_OBDII_GetModuleName)
INIT_DLL_FUNCTION_NAMED(VOID, WINAPI, GetVersion,(CHAR* szVersion, INT iMaxLen), API_OBDII_GetVersion)
INIT_DLL_FUNCTION_NAMED(VOID, WINAPI, GetGUID,(GUID* pguid), API_OBDII_GetGUID);
INIT_DLL_FUNCTION_NAMED(INT, WINAPI, RequestedAPI,(INT iMaxAPI), API_OBDII_RequestedAPI);
INIT_DLL_FUNCTION_NAMED(VOID, WINAPI, GetModuleComment,(CHAR* szComment, INT iMaxLen), API_OBDII_GetModuleComment);

INIT_DLL_FUNCTION(BOOL, WINAPI, API_OBDII_SetMode, (LPVOID lpUser, enumOBDModes eOBDMode));
INIT_DLL_FUNCTION(FLOAT, WINAPI, API_OBDII_Mode1_GetRefreshRate, (LPVOID lpUser));
	
INIT_DLL_FUNCTION(VOID, WINAPI, API_OBDII_Mode1_ResetData, (LPVOID lpUser));
INIT_DLL_FUNCTION(BOOL, WINAPI, API_OBDII_Mode1_IsPIDSupported, (LPVOID lpUser, enumOBDMode1PIDs eOBDPID));
INIT_DLL_FUNCTION(BOOL, WINAPI, API_OBDII_Mode1_AddOBDPID, (LPVOID lpUser, enumOBDMode1PIDs eOBDPID));
INIT_DLL_FUNCTION(BOOL, WINAPI, API_OBDII_Mode1_RemoveAllOBDPIDs, (LPVOID lpUser));

INIT_DLL_FUNCTION(BOOL, WINAPI, API_OBDII_Mode1_Start, (LPVOID lpUser));
INIT_DLL_FUNCTION(VOID, WINAPI, API_OBDII_Mode1_GetPacket, (LPVOID lpUser, enumOBDMode1PIDs eOBDPID, API_OBDII_MSGPACKET* lpMsgPacket));
INIT_DLL_FUNCTION(BOOL, WINAPI, API_OBDII_Mode1_Stop, (LPVOID lpUser));


INIT_DLL_FUNCTION(BOOL, WINAPI, API_OBDII_Mode3_IsMILLightOn, (LPVOID lpUser));
INIT_DLL_FUNCTION(INT, WINAPI, API_OBDII_Mode3_GetNumTroubleCodes, (LPVOID lpUser));
INIT_DLL_FUNCTION(VOID, WINAPI, API_OBDII_Mode3_GetTroubleCodes, (LPVOID lpUser, DWORD* lpTroubleCodes, INT iMaxNumTrobleCodes));
INIT_DLL_FUNCTION(BOOL, WINAPI, API_OBDII_Mode3_ClearTroubleCodes, (LPVOID lpUser));

//*** OPTIONAL FUNCTIONS ***
INIT_DLL_FUNCTION(INT, WINAPI, API_OBDII_ConfigurationDialog, (LPVOID lpUser));

To read real time data after calling create, you would set the mode to read current data, then reset the PIDs to read and add only the PIDs you now want, then just start the plugin and it begins polling the COM port in a seperate thread, returning from the call immediatly.

i.e.

Code:

	if (!m_lpAD->m_vdb.GetOBDIIPlugin()->SetMode(eOBDModeCurrentData))
		TV_THROWMSGBOX("Could not set the OBD II mode to read current data!");

	if (!m_lpAD->m_vdb.GetOBDIIPlugin()->Mode1_RemoveAllOBDPIDs())
		TV_THROWMSGBOX("Could not remove PIDs from the OBD II module");

	//Just monitor speed for now
	if (!m_lpAD->m_vdb.GetOBDIIPlugin()->Mode1_AddOBDPID(eOBDPIDVehicleSpeed))
		TV_THROWMSGBOX("Could not add a PID to monitor the OBD II plug-in for!");

	if (!m_lpAD->m_vdb.GetOBDIIPlugin()->Mode1_Start())
	{
		TV_THROWMSGBOX("Could not start the OBD II plug-in!");
	}

In a timer in your program you would call Mode1_GetPacket with the PID you want and it would return the data in the following structure:

Code:

//OBD message packet recieved from the vehicle
typedef struct API_OBDII_MSGPACKET {
	DWORD m_dwTimeRecieved;
	BYTE m_iNumDataBytes;
	BYTE m_Header[API_OBDII_NUMHEADERBYTES];
	BYTE m_Data[API_OBDII_NUMDATABYTES];
};