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When I use the Isystem BDM for the Star12 DP256, and using some third party CAN software, I get a TRUE returned from a function which tells if the bus is in limp home mode. When this happens it is OK to disable the CAN tranciever, which I do by pulling the ENE and STBY pins low. Without the BDM, of course I can't debug, but the ENE and STBY never go low, under the excact same bus circumstances from the tester. This is indicating the limp home routine returns FALSE even when the bus should be in limp home state. The BDM doesn't connect directly to any CAN lines. We are using CAN0 and this is an 80 pin device. I verifed the program in flash is the same as the code downloaded to the BDM. Does anyone know how just having the BDM connected could affect the CAN bus? I hope someone can shed some light on this, as I have a deadling coming real soon, and don't have a clue as to what to do next. - Kevin Longworth |
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BDM and CAN BUS interaction
Started by ●December 9, 2002
Reply by ●December 9, 20022002-12-09
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Kevin, Does the CAN bus operate normally otherwise when the BDM tool is not connected? If not it may be that your code is writing a '0' to the CANE bit (write once in normal modes) in the CANCTL1 register, disabling the CAN module. If this is the case, the code works when the BDM tool is connected because the BDM tool/software is resetting the part in Special mode and the CANE bit is write anytime in Special mode. Check out the CAN register initialization sequence. Regards, Gordon "Longworth, Kevin" wrote: > > When I use the Isystem BDM for the Star12 DP256, and using some third party > CAN software, I get a TRUE returned from a function which tells if the bus > is in limp home mode. When this happens it is OK to disable the CAN > tranciever, which I do by pulling the ENE and STBY pins low. Without the > BDM, of course I can't debug, but the ENE and STBY never go low, under the > excact same bus circumstances from the tester. This is indicating the limp > home routine returns FALSE even when the bus should be in limp home state. > The BDM doesn't connect directly to any CAN lines. We are using CAN0 and > this is an 80 pin device. I verifed the program in flash is the same as the > code downloaded to the BDM. Does anyone know how just having the BDM > connected could affect the CAN bus? I hope someone can shed some light on > this, as I have a deadling coming real soon, and don't have a clue as to > what to do next. > > - Kevin Longworth > > > -------------------- > > ">http://docs.yahoo.com/info/terms/ -- =============================================================== Gordon Doughman Ph: 937-438-6811 Motorola Semiconductor Fax: 937-434-7457 Field Applications Engineer Pager: 800-759-8352 Pin: 1304089 Suite 175 3131 Newmark Drive Miamisburg, OH 45342 Check out my HC12 book at: http://www.rtcgroup.com/books/ |
Reply by ●December 9, 20022002-12-09
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Yes, the CAN0 bus works normally otherwise. - Kevin -----Original Message----- From: Gordon Doughman [mailto:] Sent: Monday, December 09, 2002 9:38 AM To: Subject: Re: [68HC12] BDM and CAN BUS interaction Kevin, Does the CAN bus operate normally otherwise when the BDM tool is not connected? If not it may be that your code is writing a '0' to the CANE bit (write once in normal modes) in the CANCTL1 register, disabling the CAN module. If this is the case, the code works when the BDM tool is connected because the BDM tool/software is resetting the part in Special mode and the CANE bit is write anytime in Special mode. Check out the CAN register initialization sequence. Regards, Gordon "Longworth, Kevin" wrote: > > When I use the Isystem BDM for the Star12 DP256, and using some third party > CAN software, I get a TRUE returned from a function which tells if the bus > is in limp home mode. When this happens it is OK to disable the CAN > tranciever, which I do by pulling the ENE and STBY pins low. Without the > BDM, of course I can't debug, but the ENE and STBY never go low, under the > excact same bus circumstances from the tester. This is indicating the limp > home routine returns FALSE even when the bus should be in limp home state. > The BDM doesn't connect directly to any CAN lines. We are using CAN0 and > this is an 80 pin device. I verifed the program in flash is the same as the > code downloaded to the BDM. Does anyone know how just having the BDM > connected could affect the CAN bus? I hope someone can shed some light on > this, as I have a deadling coming real soon, and don't have a clue as to > what to do next. > > - Kevin Longworth > > > -------------------- > <http://www.motorola.com/mcu > ">http://docs.yahoo.com/info/terms/ <http://docs.yahoo.com/info/terms/> -- =============================================================== Gordon Doughman Ph: 937-438-6811 Motorola Semiconductor Fax: 937-434-7457 Field Applications Engineer Pager: 800-759-8352 Pin: 1304089 Suite 175 3131 Newmark Drive Miamisburg, OH 45342 Check out my HC12 book at: http://www.rtcgroup.com/books/ <http://www.rtcgroup.com/books/ <http://rd.yahoo.com/M$0188.2647639.4038785.2225243/D=egroupweb/S065542 05:HM/A21406/R=0/*http://www.e-dealsdaily.com/soundbug/> <http://us.adserver.yahoo.com/l?M$0188.2647639.4038785.2225243/D=egroupmai l/S=:HM/A21406/rand4221514> -------------------- <http://www.motorola.com/mcu ">http://docs.yahoo.com/info/terms/> . |
Reply by ●December 10, 20022002-12-10
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Update, the problem was a missing common ground from the test pc with Vector's cancardx and the DUT. I put earthgournd on the neg terminal of the DUT power supply and the problem went away. I didn't investigate further, but I suspect the BDM ground was connected to earth ground and allowed it to work properly - Kevin -----Original Message----- From: Longworth, Kevin Sent: Monday, December 09, 2002 1:35 PM To: Subject: RE: [68HC12] BDM and CAN BUS interaction Yes, the CAN0 bus works normally otherwise. - Kevin -----Original Message----- From: Gordon Doughman [mailto:] Sent: Monday, December 09, 2002 9:38 AM To: Subject: Re: [68HC12] BDM and CAN BUS interaction Kevin, Does the CAN bus operate normally otherwise when the BDM tool is not connected? If not it may be that your code is writing a '0' to the CANE bit (write once in normal modes) in the CANCTL1 register, disabling the CAN module. If this is the case, the code works when the BDM tool is connected because the BDM tool/software is resetting the part in Special mode and the CANE bit is write anytime in Special mode. Check out the CAN register initialization sequence. Regards, Gordon "Longworth, Kevin" wrote: > > When I use the Isystem BDM for the Star12 DP256, and using some third party > CAN software, I get a TRUE returned from a function which tells if the bus > is in limp home mode. When this happens it is OK to disable the CAN > tranciever, which I do by pulling the ENE and STBY pins low. Without the > BDM, of course I can't debug, but the ENE and STBY never go low, under the > excact same bus circumstances from the tester. This is indicating the limp > home routine returns FALSE even when the bus should be in limp home state. > The BDM doesn't connect directly to any CAN lines. We are using CAN0 and > this is an 80 pin device. I verifed the program in flash is the same as the > code downloaded to the BDM. Does anyone know how just having the BDM > connected could affect the CAN bus? I hope someone can shed some light on > this, as I have a deadling coming real soon, and don't have a clue as to > what to do next. > > - Kevin Longworth > > > -------------------- > <http://www.motorola.com/mcu> <http://www.motorola.com/mcu <http://www.motorola.com/mcu> > > > > ">http://docs.yahoo.com/info/terms/ <http://docs.yahoo.com/info/terms/> <http://docs.yahoo.com/info/terms/ <http://docs.yahoo.com/info/terms/> > -- =============================================================== Gordon Doughman Ph: 937-438-6811 Motorola Semiconductor Fax: 937-434-7457 Field Applications Engineer Pager: 800-759-8352 Pin: 1304089 Suite 175 3131 Newmark Drive Miamisburg, OH 45342 Check out my HC12 book at: http://www.rtcgroup.com/books/ <http://www.rtcgroup.com/books/> <http://www.rtcgroup.com/books/ <http://www.rtcgroup.com/books/> <http://rd.yahoo.com/M$0188.2647639.4038785.2225243/D=egroupweb/S065542 <http://rd.yahoo.com/M$0188.2647639.4038785.2225243/D=egroupweb/S065542 > 05:HM/A21406/R=0/*http://www.e-dealsdaily.com/soundbug/ <http://www.e-dealsdaily.com/soundbug/> > <http://us.adserver.yahoo.com/l?M$0188.2647639.4038785.2225243/D=egroupmai <http://us.adserver.yahoo.com/l?M$0188.2647639.4038785.2225243/D=egroupmai > l/S=:HM/A21406/rand4221514> -------------------- <http://www.motorola.com/mcu> <http://www.motorola.com/mcu <http://www.motorola.com/mcu> ">http://docs.yahoo.com/info/terms/ <http://docs.yahoo.com/info/terms/> > . <http://rd.yahoo.com/M$0188.2647639.4038785.2225243/D=egroupweb/S065542 05:HM/A21406/R=0/*http://www.e-dealsdaily.com/soundbug/> <http://us.adserver.yahoo.com/l?M$0188.2647639.4038785.2225243/D=egroupmai l/S=:HM/A21406/randf3640077> -------------------- <http://www.motorola.com/mcu ">http://docs.yahoo.com/info/terms/> . |
