DESIGN OF A CUSTOM ASIC INCORPORATING CAN™ AND 1 ...

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The CAN protocol was designed for short messages, no more than eight bytes long. The protocol never interrupts an ongoing transmission, but it assigns priorities to messages to prevent conflicts and to make sure that urgent messages are delivered first, and includes error checking to make the communications highly reliable. Figure 3.1 Typical CAN Bus Network. Most network applications follow a layered approach to system implementation, which enables interoperability between products from different manufacturers. A standard was created by the ISO as a template to follow for this layered approach. It is called the ISO Open Systems Interconnection (OSI) Network Layering Reference Model and is shown in Figure 3.2 for reference. The CAN protocol itself implements most of the lower two layers of this reference model. The communication medium portion of the model was purposely left out of the Bosch CAN specification to enable system designers to adapt and optimize the communication 43
protocol on multiple media for maximum flexibility (twisted pair, single wire, optically isolated, RF, IR, etc.). With this flexibility, however, comes the possibility of interoperability concerns. Figure 3.2 ISO/OSI Reference Model. To ease some of these concerns, the ISO and Society of Automotive Engineers (SAE) have defined some protocols based on CAN that include the Media Dependent Interface definition such that all of the lower two layers are specified. ISO11898 is a standard for high- speed applications. ISO11519 is a standard for low-speed applications, and J1939 is targeted for truck and bus applications. All three of these protocols specify a 5V differential electrical bus as the physical interface. The rest of the layers of the ISO/OSI protocol stack are left to be implemented by the system software developer. Higher Layer Protocols (HLPs) are generally used to implement the upper five layers of the OSI Reference Model. HLPs are used to: standardize startup procedures 44
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DESIGN OF A CUSTOM ASIC INCORPORATI
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ABSTRACT The vast majority of today
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LIST OF ABBREVIATIONS AND SYMBOLS A
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ISO International Organization for
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SI Serial In SO Serial Out SOF Star
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ACKNOWLEDGEMENTS I would like to ex
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2.4 Types of Devices...............
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4.3.5 Communication Speed Different
Page 17 and 18: 5.3.21.1 Synchronization Test (test
Page 19 and 20: 5.3 Resource Utilization...........
Page 21 and 22: LIST OF FIGURES 2.1 1 - Wire® Netw
Page 23 and 24: 4.12 Read-Data Time Slot...........
Page 25 and 26: 6.4 DS1996 Address Registers ......
Page 27 and 28: manufacturing process. Structured o
Page 29 and 30: describes the 1 - Wire® and CAN co
Page 31 and 32: 2.2 1 - Wire® Overview The basis o
Page 33 and 34: All 1 - Wire® masters described in
Page 35 and 36: attachments, microcontroller with b
Page 37 and 38: Figure 2.3 Bidirectional port pin w
Page 39 and 40: 2.3.3 Synthesizable 1 - Wire® Bus
Page 41 and 42: Figure 2.7 UART/RS232 Serial Port I
Page 43 and 44: hardware. Through control registers
Page 45 and 46: Table 2.2 1 - Wire® Bus Operations
Page 47 and 48: 2.3.6 1 - Wire® Search Algorithm F
Page 49 and 50: detected. This ‘read two bits’
Page 51 and 52: in Figure 2.15. Alternatively, the
Page 53 and 54: of the bit, then write the desired
Page 55 and 56: 2.4.2 Device Functions and Typical
Page 57 and 58: and development (R&D) investments b
Page 59 and 60: 2.5 Network Types and Precedents As
Page 61 and 62: 2.5.2 1 - Wire® Network Topologies
Page 63 and 64: 2.5.3 1 - Wire® Network Limitation
Page 65 and 66: with a single selected slave. If an
Page 67: user group was founded in March of
Page 71 and 72: ecessive bit and the monitored stat
Page 73 and 74: specification: Start-Of-Frame, Arbi
Page 75 and 76: Cyclic Redundancy Check (CRC) Field
Page 77 and 78: Arbitration FieldThe Arbitration Fi
Page 79 and 80: SOF SOF Bit 28 Bit 27 Arbitration f
Page 81 and 82: Afterwards it starts transmitting s
Page 83 and 84: Figure 3.9 Structure of the Interfr
Page 85 and 86: error occurs, an Error Frame is gen
Page 87 and 88: Table 3.4 Error Flag Output Timing
Page 89 and 90: 3.5.2 Error-Passive A node becomes
Page 91 and 92: where tNBT is the Nominal Bit Time
Page 93 and 94: Figure 3.12 Propagation Delay Betwe
Page 95 and 96: 3.6.4 Synchronization t t t t (3.
Page 97 and 98: opposite value is inserted into the
Page 99 and 100: many systems, the bus length will b
Page 101 and 102: CHAPTER 4 THE CHALLENGES OF INTERFA
Page 103 and 104: In June 2004, Maxim Integrated Prod
Page 105 and 106: Wearable sensor technology is a new
Page 107 and 108: In traditional bus architectures, o
Page 109 and 110: Figure 4.3 Centralized arbiter with
Page 111 and 112: For the initial prototype design pr
Page 113 and 114: the ID of 31 transmits a ‘0’ (d
Page 115 and 116: Recently, a technique has been prop
Page 117 and 118: procedure, then the address claim p
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paradigms are prevalent in the desi
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systems possess a higher flexibilit
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fixed identifier and hence a fixed
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348sm Cm 47 8 smbit 11-bit hea
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est-case latency occurs when the bu
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to break the 1 - Wire® network int
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ow, is most critical for power deli
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computations have device-specific p
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Table 4.7 Example results with N 2
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4.3.5 Communication Speed Different
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anging” a port pin on a microproc
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From Figure 5.1, the block I/O pins
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5.2.2 Command Register In addition
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specifies the selected bit value to
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with i > m. This process is repeate
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Figure 5.6 Interrupt Register. OW_
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the INTR pin will be pulled high si
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master reset occurs. Table 5.2 show
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EN_FOW: Enable Force One Wire. Sett
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READ_ROM - Used to read the 64-bit
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5.2.8.1 Single Search ROM (single_s
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5.2.8.3 Scratchpad Memory (scratchp
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5.2.8.4 Command Recognition (cmd_re
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TBF - The Transmit Buffer provides
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compensate for the propagation dela
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Figure 5.15 CAN Module memory map [
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‘0’, fast speed mode will be us
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COMP-SEL: Comparator Select. When t
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Figure 5.18 CAN Status Register. B
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that buffer is given to the CPU and
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Acceptance Mask Registers (accepted
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SJW1, SJW0: Synchronization Jump Wi
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TSEG22 - TSEG10: Time Segment Bits.
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The transmit clock (ttxclk) is used
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5.3.13 CAN Module Transmit Buffer I
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Figure 5.28 CAN Transmit Data Segme
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5.3.20 CAN Node Overview As stated
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Read Digital InputsRead the value o
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the clock high time is either 5 µs
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Yes Perform A/D Conversion on AN0 W
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and GP2 and GP5 as outputs. With th
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external INT pin, and then branches
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Read MCP2515 Rx Buffer for Digital
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When a valid message is received, t
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Table 5.19 Resource Utilization. Re
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For this test, only one CAN node wa
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an Error Frame to be generated. Aft
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messages, acknowledge messages, or
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5.3.21.4 Send Basic Frame Test (sen
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going from one node to 30 nodes (se
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Table 6.1 Resource Utilization. Rev
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6.2.1 Test Verification and Overvie
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has read access to this register. T
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system configuration used for this
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or not depends on the number of rec
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6.4. There are two receiving CAN no
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CHAPTER 7 CONCLUSIONS AND FUTURE WO
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a communication bus reset will occu
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For the synthesizable CAN Controlle
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additional CAN nodes were added to
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Fall-Through Stack A LOW level on t
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In conclusion, the prototype system
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REFERENCES [1] IBM ASIC Products Ap
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[22] “CAN - a brief tutorial for
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[44] Microchip MCP2515 - Stand-Alon
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[67] K. Tindell and A. Burns, “Gu
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[88] “Verilog - A Language Refere
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