spirilis 1,265 Posted August 2, 2013 Share Posted August 2, 2013 (edited) 43oh Store: Buy the CAN BoosterPack for $14.99. This is a universal BoosterPack for enabling CAN I/O for all the LaunchPad-capable products. It sports an NXP TJA1051T/3 CAN transceiver which includes a "V_IO" rail for doing native 3.3V CMOS I/O with the CAN controller. Included is the footprint for the Microchip MCP2515, SPI CAN Controller. This is used to enable CAN connectivity for devices that do not have it natively supported. This is optional though. If you do not need the MCP2515, the CAN_RX and CAN_TX pads can be soldered to breakout pads inside the boosterpack arrangement that correspond to the requisite pins on the LaunchPad which have CAN capability. Stellaris/Tiva and Hercules LaunchPads should be able to take advantage of this. In that arrangement, the boosterpack simply supplies the CAN transceiver (physical-layer interface) as well as connectivity ports and the ability to supply or tap into a 5V rail going along the RJ45/CAT5 bus. I decided to choose RJ45 (non-magjack) for the physical connection, primarily due to its versatility as a way to chain multiple LaunchPads together into a long-distance CAN bus arrangement and due to its general-purpose nature. Most people use CAN to connect to their automobile; for this I will be producing a daughterboard that converts DE9 (DB9) OBD-II standard pinout into the Industrial CAN RJ45 standard, including the adaption of 12V automotive power down to 5V for powering the LaunchPad. An OBD-II to DE9 cable will need to be supplied separately to connect this arrangement but they are easy to come by; see here for an example: https://www.sparkfun.com/products/10087 Support for terminating the CAN bus is included, and this board supports the Split-Bus configuration with two 60R resistors and a single 4.7nF capacitor to provide a noise sink. This should be done at either end of the CAN bus, but nodes in the middle shouldn't need it. If any nodes are connected to the bus with a stub (not in-line but branched off using some sort of 3-port concentrator), it is recommended they use termination with two 1.3K-ohm resistors. This is not likely necessary thanks to the two RJ45 ports provided on the board which facilitate connecting nodes "in-line" to the bus. The 5V rail (CAN_V+) in the RJ45 connection can be attached directly to the LaunchPad's 5V rail in order to let the LaunchPad supply power to the whole bus, or it can be connected through a Current-Limiting IC to supply the LaunchPad's 5V rail along with bulk capacitance (SMD 1206 and/or PTH aluminum electrolytic capacitors; supply bulk capacitance to the board to survive long-distance cabling). To support using the 5V supply from the MSP430 LaunchPad, a "5VTAP" pad in the upper left is supplied which you can connect to TP1 (right behind the USB connector). If you are powering the MSP430 LaunchPad from the CAN bus itself this is not needed (the MCP1725 voltage regulator will supply the 3.3V Vcc rail). OSHpark mockup pics: !!! NOTE : this design has major bugs, update forthcoming !!! Schematic (PDF): DipTrace Schematic - SPI_CAN_BPak_draft1.pdf OSHpark gerbers: OSH_SPICAN_v10.zip Elecrow/Seeed/ITead gerbers: Elecrow_SPICANv10_5x10.zip !!! NOTE : this design has major bugs, update forthcoming !!! This board is intended to use the 5x10cm PCB service from the Chinese fabs. Edited February 13, 2014 by bluehash [ADMIN] - Add store link. reaper7, Automate, dubnet and 2 others 5 Quote Link to post Share on other sites
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.