Problem with ST710 library CAN identifier manipulation macros

[parrino]

Posted on January 10, 2006 at 15:21

Problem with ST710 library CAN identifier manipulation macros

[parrino]

Posted on December 12, 2005 at 10:37

Hello

I have a problem with CAN identifier manipulation macros. For exemple, I want to send on the CAN bus the nine following CAN messages with extended identifiers Id=0x00107F0, DLC=8, Data=[0x08, 0x17, 0x26, 0x35, 0x44, 0x53, 0x62, 0x71]) Id=0x00107EF, DLC=7, Data=[0x27, 0x36, 0x45, 0x54, 0x63, 0x75, 0x86]) Id=0x00107EE, DLC=6, Data=[0x46, 0x56, 0x65, 0x74, 0x83, 0x95]) Id=0x00107ED, DLC=5, Data=[0x65, 0x76, 0x85, 0x94, 0xA3]) Id=0x00107EC, DLC=4, Data=[0x84, 0x96, 0xA5, 0xB4]) Id=0x00107EB, DLC=3, Data=[0xA3, 0xB6, 0xC5]) Id=0x00107EA, DLC=2, Data=[0xC2, 0xD6]) Id=0x00107E9, DLC=1, Data=[0xE1]) Id=0x00107E8, DLC=0, Data=[]) I used STR710-EVAL board to send CAN messages on one side and CANalyser in spy mode to read CAN messages on the other side. When I use ST macro, CANalyser read Id=(0x1FC00020), DLC=8, Data=0x08, 0x17, 0x26, 0x35, 0x44, 0x53, 0x62, 0x71 Id=(0x1FBC0020), DLC=7, Data=0x27, 0x36, 0x45, 0x54, 0x63, 0x75, 0x86 And so on ... But if I replace (in function CAN_SendMessage, file can.c) : ''CAN->sMsgObj[0].A1R = EXT_FIXED_ID_ARB_L(pCanMsg->Id);'' by ''CAN->sMsgObj[0].A1R = 0xFFFF & pCanMsg->Id;'' and ''CAN->sMsgObj[0].A2R = (CAN->sMsgObj[0].A2R & 0xE000) | EXT_FIXED_ID_ARB_H(pCanMsg->Id);'' by ''CAN->sMsgObj[0].A2R = (CAN->sMsgObj[0].A2R & 0xE000) | (0x1FFF0000 & pCanMsg->Id) >>16;'' CANalyser read good identifiers : Id=(0x107F0), DLC=8, Data=0x08, 0x17, 0x26, 0x35, 0x44, 0x53, 0x62, 0x71 Id=(0x107EF), DLC=7, Data=0x27, 0x36, 0x45, 0x54, 0x63, 0x75, 0x86 And so on ... Can you tell me what is the problem ? Thanks for your answer

[davidbellegarde9]

Posted on December 14, 2005 at 13:02

About the Id, here is the way the code is implemented:

The pCanMsg->Id software buffer: bit[28..0] EXT Id part, STD id part MSB------------------LSB Then it is dispatched in the A1R and A2R (arbitration registers as follow: A2R[12..2] for the STDID MSB----LSB (ID[28..18] of A2R) A2R[1..0] A1R[15..0] for the extended part MSB---------------LSB (ID[17..16] of A2R and ID[15..0] of A1R) Then a trame is sent or received as follow: STDID[10..0] EXTID[17..0] MSB-----LSB MSB-------LSB Finally, the CANanalyser read this: STDID[28..18] EXTID[17..0] MSB-----------------------LSB So if you compare the beginning and the end you should see a swap between the STDID and the EXTID, this should explain the problem. In fact there is no problem, I tried with your fisrt message ID and it works well. From a CAN arbitration point of view, the STDID must be the MSBs but the code was not implemented like this. I think you could add a little function which would handle the Id. e.g. /*swap the Id*/ CAN_HandleId(canmsg* pCanMsg, u32 Id) { pCanMsg->Id = ((Id & 0x3FFFF)< (Id & 0x1FFC0000)>>18)); }

[parrino]

Posted on January 10, 2006 at 15:21

Hi Squirrel !

First, Happy new year ! You are right ! To have a good interpretation of extended Id, I use * before send : u32 can2libst(u32 Id) { return ((Id&0x1FFC0000)>>18) | ((Id&0x3FFFF)<} * after receive : u32 libst2can(u32 Id) { return ((Id&0x7FF)<>11); } And it works perfectly with ST functions. For standard ID, there is no problem and so I don't use the previous functions. But now I have a problem with receive mask. ST functions provide function to receive a range of Ids [LowId, HighId] : CAN_SetRxMsgObj It works with [0, CAN_LAST_STD_ID] for standard ID or [0, CAN_LAST_EXT_ID] for extended Id. For other values, the result is strange... If I want to receive, for example standard Id range [5, 15], I never receive the Id 10 message sent by CANalyzer. But if use Id range [8, 11], I receive it ! I don't really understand how works mask and arbitration macros RANGE_ID_MSK and RANGE_ID_ARB. When I read documentation, I understand the following : If Mask Bit n = 1, Arbitration bit n is used to filter message If Mask Bit n = 0, Arbitration bit n isn't used. For example : Mask = 0xC and Arb = 0x9 In binary : 1100 Mask 1001 Arb 10xx Accepted Id So accepted Ids should be (in binary) 1000, 1001, 1010 and 1011 (ie 0x8, 0x9, 0xA, 0xB) Is my interpretation correct ? And what is wrong with my use of the CAN_SetRxMsgObj function ? Thanks for your help !