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Hi, What will be a simple CAN bus driver. Can I just connect a half duplex multi-drop RS485 driver to the TX and RX pins. How does the DP256 CAN handle the TX enable of a RS485 chip for instance. I suppose that a isolated configuration is possible with a one wire current loop configuration. Any ideas. Frank van der Merwe |
CANbus driver
Started by ●October 10, 2002
Reply by ●October 10, 20022002-10-10
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Hi, What will be a simple CAN bus driver. Can I just connect a half duplex multi-drop RS485 driver to the TX and RX pins. How does the DP256 CAN handle the TX enable of a RS485 chip for instance. I suppose that a isolated configuration is possible with a one wire current loop configuration. Any ideas. Frank van der Merwe |
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Reply by ●October 10, 20022002-10-10
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In the early days of CAN we used to use the RS-485 drivers by wiring the txenable pin to the CAN TX pin. I guess the question would be, why not just use the available, and better suited, CAN tranceivers that are available? Steve Zanthic Technologies Inc. is located at www.zanthic.com Your Controller Area Networking Experts! Embedded micro-controllers and CAN interface devices sold here ----- Original Message ----- From: Francois To: Sent: Thursday, October 10, 2002 10:36 AM Subject: [68HC12] CANbus driver Hi, What will be a simple CAN bus driver. Can I just connect a half duplex multi-drop RS485 driver to the TX and RX pins. How does the DP256 CAN handle the TX enable of a RS485 chip for instance. I suppose that a isolated configuration is possible with a one wire current loop configuration. Any ideas. Frank van der Merwe -------------------- ">http://docs.yahoo.com/info/terms/ |
Reply by ●October 10, 20022002-10-10
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Hi, I am basically looking or the cheapest and practical implementation. There is the MC33388 which I assume takes care of "muting the TX driver " - I just trying to avoid specalty parts that might go out of scope and does not have a second source. How about a open collector arrangement using RS485 drivers, with a wired orr configuration on the buss. So any slave can engage the buss. I guess that if it is open collector driven with pullups, then there is no need to "mute" the transmitter. However I am not sure of the loopback issues - any clues allong this simplified implementation - im not an expert on CAN. What other drivers are available similar to the MC33388?? Frank van der Merwe ----- Original Message ----- From: "Steve Letkeman" <> To: <> Sent: Thursday, October 10, 2002 10:32 AM Subject: Re: [68HC12] CANbus driver > In the early days of CAN we used to use the RS-485 drivers > by wiring the txenable pin to the CAN TX pin. I guess the > question would be, why not just use the available, and better > suited, CAN tranceivers that are available? > > Steve > > Zanthic Technologies Inc. is located at www.zanthic.com > Your Controller Area Networking Experts! > Embedded micro-controllers and CAN interface devices sold here > > ----- Original Message ----- > From: Francois > To: > Sent: Thursday, October 10, 2002 10:36 AM > Subject: [68HC12] CANbus driver > > > Hi, > > What will be a simple CAN bus driver. Can I just connect a half duplex > multi-drop RS485 driver to the > TX and RX pins. How does the DP256 CAN handle the TX enable of a RS485 chip > for instance. I suppose that a isolated configuration is possible with a > one > wire current loop configuration. Any ideas. > > Frank van der Merwe > > > -------------------- > > ">http://docs.yahoo.com/info/terms/ > -------------------- > > ">http://docs.yahoo.com/info/terms/ |
Reply by ●October 10, 20022002-10-10
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How about a 82C250 or SI9200 CAN transceiver, about the same price 8 pin
SO Dale Kelley -----Original Message----- From: Francois [mailto:] Sent: Thursday, October 10, 2002 11:54 AM To: Subject: [68HC12] CANbus driver Hi, What will be a simple CAN bus driver. Can I just connect a half duplex multi-drop RS485 driver to the TX and RX pins. How does the DP256 CAN handle the TX enable of a RS485 chip for instance. I suppose that a isolated configuration is possible with a one wire current loop configuration. Any ideas. Frank van der Merwe -------------------- ">http://docs.yahoo.com/info/terms/ ------------------------ This message is for the designated recipient only and may contain privileged, proprietary, or otherwise private information. If you have received it in error, please notify the sender immediately and delete the original. Any unauthorized use of this email is prohibited. ------------------------ |
Reply by ●October 10, 20022002-10-10
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you can run a CAN bus on a limited size network using a simple wired OR configuration but it wouldn't be practical for leaving the board any distance. There are standard devices like the 82C250 mentioned that have pinouts that are duplicated by a number of devices by a number of manufacturers, so I don't think you have to worry about them not being available. The idea behind CAN is that each transceiver sees it's own driven level on the bus and everybody else's also. If the local node is in a non-dominant state and another node is dominant than the local node backs off because it lost arbitration. The lower the CAN ID, the higher the priority and the more chance it gets through over the lower priority message. (this is the simplified version) Steve Hi, I am basically looking or the cheapest and practical implementation. There is the MC33388 which I assume takes care of "muting the TX driver " - I just trying to avoid specalty parts that might go out of scope and does not have a second source. How about a open collector arrangement using RS485 drivers, with a wired orr configuration on the buss. So any slave can engage the buss. I guess that if it is open collector driven with pullups, then there is no need to "mute" the transmitter. However I am not sure of the loopback issues - any clues allong this simplified implementation - im not an expert on CAN. What other drivers are available similar to the MC33388?? Frank van der Merwe ----- Original Message ----- From: "Steve Letkeman" <> To: <> Sent: Thursday, October 10, 2002 10:32 AM Subject: Re: [68HC12] CANbus driver > In the early days of CAN we used to use the RS-485 drivers > by wiring the txenable pin to the CAN TX pin. I guess the > question would be, why not just use the available, and better > suited, CAN tranceivers that are available? > > Steve > > Zanthic Technologies Inc. is located at www.zanthic.com > Your Controller Area Networking Experts! > Embedded micro-controllers and CAN interface devices sold here > > ----- Original Message ----- > From: Francois > To: > Sent: Thursday, October 10, 2002 10:36 AM > Subject: [68HC12] CANbus driver > > > Hi, > > What will be a simple CAN bus driver. Can I just connect a half duplex > multi-drop RS485 driver to the > TX and RX pins. How does the DP256 CAN handle the TX enable of a RS485 chip > for instance. I suppose that a isolated configuration is possible with a > one > wire current loop configuration. Any ideas. > > Frank van der Merwe > > > -------------------- > > ">http://docs.yahoo.com/info/terms/ > -------------------- > > ">http://docs.yahoo.com/info/terms/ -------------------- ">http://docs.yahoo.com/info/terms/ |
Reply by ●October 10, 20022002-10-10
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IMHO you should very seriously consider just using a bus driver designed for
CAN. There are a number of features built-in that you can take advantage of that would not be present in an RS485 chip set--even if you figured out a way to deal with bus arbitration. (Have you read up on that yet?) The original 82C250 from Philips is the classic device, and Philips has some replacement devices too. There's the Motorola MC33388. TI makes an SN65LBC031, which is sold in DigiKey. There are a number of others, too. You should have absolutely no fears about there not being a source of CAN bus drivers. There are tens of millions of CAN nodes every year in the automotive market alone. CAN is becoming more prevalent in automotive, not less. There are many hundreds of thousands of CAN nodes every year in industrial control applications too--such as DeviceNet. Best regards, Kerry Berland Silicon Engines 2101 Oxford Road Des Plaines, IL 60018 USA 847-803-6860 Fax 847-803-6870 ----- Original Message ----- From: Francois To: Sent: Thursday, October 10, 2002 1:05 PM Subject: Re: [68HC12] CANbus driver Hi, I am basically looking or the cheapest and practical implementation. There is the MC33388 which I assume takes care of "muting the TX driver " - I just trying to avoid specalty parts that might go out of scope and does not have a second source. How about a open collector arrangement using RS485 drivers, with a wired orr configuration on the buss. So any slave can engage the buss. I guess that if it is open collector driven with pullups, then there is no need to "mute" the transmitter. However I am not sure of the loopback issues - any clues allong this simplified implementation - im not an expert on CAN. What other drivers are available similar to the MC33388?? Frank van der Merwe ----- Original Message ----- From: "Steve Letkeman" <> To: <> Sent: Thursday, October 10, 2002 10:32 AM Subject: Re: [68HC12] CANbus driver > In the early days of CAN we used to use the RS-485 drivers > by wiring the txenable pin to the CAN TX pin. I guess the > question would be, why not just use the available, and better > suited, CAN tranceivers that are available? > > Steve > > Zanthic Technologies Inc. is located at www.zanthic.com > Your Controller Area Networking Experts! > Embedded micro-controllers and CAN interface devices sold here > > ----- Original Message ----- > From: Francois > To: > Sent: Thursday, October 10, 2002 10:36 AM > Subject: [68HC12] CANbus driver > > > Hi, > > What will be a simple CAN bus driver. Can I just connect a half duplex > multi-drop RS485 driver to the > TX and RX pins. How does the DP256 CAN handle the TX enable of a RS485 chip > for instance. I suppose that a isolated configuration is possible with a > one > wire current loop configuration. Any ideas. > > Frank van der Merwe > > > -------------------- > > ">http://docs.yahoo.com/info/terms/ > -------------------- > > ">http://docs.yahoo.com/info/terms/ -------------------- |
