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

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2.3.5 Timing/Transaction Sequence on the 1 – Wire® Bus In any 1 – Wire® network, there are four basic signaling operations that comprise all device communications: Reset, Write ‘0’ bit, Write ‘1’ bit, and Read bit. Referring back to Figure 2.2, these four signaling operations are an integral part of each step in the typical 1 – Wire® communication flow. The 1 – Wire® bus requires strict signaling protocol to ensure data integrity. A typical 1 – Wire® transaction sequence consists of four steps: Initialization, ROM (read-only-memory) Function Command, Memory Function Command, if applicable (not all 1 – Wire® devices support these commands, i.e. identification (ID) only devices), and Transaction/Data. An initialization sequence begins when the bus master drives a defined length “Reset” pulse that synchronizes the entire bus. Every slave then responds to the “Reset” pulse with a logic low “Presence” pulse. To write data, the master first initiates a time slot by driving the 1 – Wire® line low, and then, either holds the line low (wide pulse) to transmit a logic ‘0’ or releases the line (short pulse) to allow the bus to return to the logic ‘1’ state. To read data, the master again initiates a time slot by driving the line with a narrow low pulse. A slave can then either return a logic ‘0’ by turning on its open-drain output and holding the line low to extend the pulse, or return a logic ‘1’ by leaving the open-drain output off to allow the line to recover. Table 2.2 provides a list of operations and implementation steps for standard speed communications (overdrive speeds are shown in parentheses) on a typical 1 – Wire® bus network. Figures 2.10 through 2.13 show scope traces of the 1 – Wire® operations described in Table 2.2. 19
Table 2.2 1 – Wire® Bus Operations. Operation Description Implementation Reset Write ‘0’ Bit Write ‘1’ Bit Read Bit Reset all of the 1 – Wire® bus slave devices and get them ready for a command. Send ‘0’ bit to all of the 1 – Wire® slaves (Write ‘0’ slot time). Send ‘1’ bit to all of the 1 – Wire® slaves (Write ‘1’ slot time). Read a bit from the 1 - Wire® slaves (Read time slot). 20 Delay 0µs. (2.5µs) Drive the bus low, delay 480µs. (70µs) Release the bus, delay 70µs. (8.5µs) Sample the bus: ‘0’ = device(s) present, ‘1’ = no device present. Delay 410µs. (40µs) Drive the bus low, delay for 60µs. (7.5µs) Release the bus, delay for 10µs. (2.5µs) Drive the bus low, delay for 6µs. (1.0µs) Release the bus, delay for 64µs. (7.5µs) Drive the bus low, delay for 6µs. (1.0µs) Release the bus, delay for 9µs. (1.0µs) Sample the bus to read from slave(s), delay for 55µs. (7µs) Figure 2.10 Reset/Presence Detect Sequence.
Page 1 and 2: DESIGN OF A CUSTOM ASIC INCORPORATI
Page 3 and 4: ABSTRACT The vast majority of today
Page 5 and 6: LIST OF ABBREVIATIONS AND SYMBOLS A
Page 7 and 8: ISO International Organization for
Page 9 and 10: SI Serial In SO Serial Out SOF Star
Page 11 and 12: ACKNOWLEDGEMENTS I would like to ex
Page 13 and 14: 2.4 Types of Devices...............
Page 15 and 16: 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: hardware. Through control registers
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 and 68: user group was founded in March of
Page 69 and 70: protocol on multiple media for maxi
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
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3.6.4 Synchronization t t t t (3.
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opposite value is inserted into the
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many systems, the bus length will b
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CHAPTER 4 THE CHALLENGES OF INTERFA
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In June 2004, Maxim Integrated Prod
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Wearable sensor technology is a new
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In traditional bus architectures, o
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Figure 4.3 Centralized arbiter with
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For the initial prototype design pr
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the ID of 31 transmits a ‘0’ (d
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Recently, a technique has been prop
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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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