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

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equested transmission was successfully completed. If, after TCS is cleared, but before transmission begins, an abort transmission command is issued then the transmit buffer will be released and TCS will remain clear. TCS will then only be set after a further transmission is both requested and successfully completed. TBA: Transmit Buffer Access. When clear, the transmit buffer is locked and cannot be accessed by the CPU. This indicates that either a message is being transmitted or is awaiting transmission. If the CPU writes to the transmit buffer while it is locked, then the data will be lost without this being signaled. While set to a ‘1’, the transmit buffer may be written to by the CPU. DO: Data Overrun. While clear, this bit indicates normal operation. This bit is set when both receive buffers are full and there is a further message to be stored. In this case the new message is dropped, but the internal logic maintains the correct protocol. The CAN Module does not receive the message, but no warning is sent to the transmitting node. The CAN Module clears the DO bit when the CPU sets the COS bit in the CCOM register. Data overrun can also be caused by a transmission, since the CAN Module will temporarily store an outgoing frame in a receive buffer in case arbitration is lost during transmission. RBS: Receive Buffer Status. This bit is set to a ‘1’ by the CAN Module when a new message is available. When clear this indicates that no message has become available since the last RRB (bit 2 of the CCOM register) command. The bit is cleared when RRB is set. However, if the second receive buffer already contains a message, then control of 151
that buffer is given to the CPU and RBS is immediately set again. The first receive buffer is then available for the next incoming message from the CAN Module. 5.3.6 CAN Module Interrupt Register (CINT) The CAN Module has only one interrupt vector assigned to it. The Interrupt Register, shown in Figure 5.19, can be read to determine the source of a CAN interrupt. The five interrupt sources include: Wake Up, Data Overrun (a third message being received before either of the Receive Buffers have been released), Error (either read or write error counter reaching a pre-determined level), Transmission Complete, and Receive Interrupt [96]. All bits of this register are read only; all are cleared by a read of this register. However, this register must be read in the interrupt handling routine in order to enable further interrupts. Figure 5.19 CAN Interrupt Register. WIF: Wake-Up Interrupt Flag. If the CAN module detects bus activity while it is in the SLEEP state, it clears the SLEEP in the CCOM register; the WIF bit will then be set. WIF is cleared by reading the CAN Interrupt Register (CINT), or by an external reset. OIF: Overrun Interrupt Flag. When OIE (bit 4 of CCNTRL register) is set this bit will be set when a data overrun condition is detected. Like all the bits in this register, OIF is cleared by reading the register, or when an external reset request is set. EIF: Error Interrupt Flag. When EIE (bit 3 of CCNTRL register) is set then this bit will be set by a change in the error or bus status bits in the CAN module status register. 152
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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
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5.3.21.1 Synchronization Test (test
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5.3 Resource Utilization...........
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LIST OF FIGURES 2.1 1 - Wire® Netw
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4.12 Read-Data Time Slot...........
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6.4 DS1996 Address Registers ......
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manufacturing process. Structured o
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describes the 1 - Wire® and CAN co
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2.2 1 - Wire® Overview The basis o
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All 1 - Wire® masters described in
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attachments, microcontroller with b
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Figure 2.3 Bidirectional port pin w
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2.3.3 Synthesizable 1 - Wire® Bus
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Figure 2.7 UART/RS232 Serial Port I
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hardware. Through control registers
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Table 2.2 1 - Wire® Bus Operations
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2.3.6 1 - Wire® Search Algorithm F
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detected. This ‘read two bits’
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in Figure 2.15. Alternatively, the
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of the bit, then write the desired
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2.4.2 Device Functions and Typical
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and development (R&D) investments b
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2.5 Network Types and Precedents As
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2.5.2 1 - Wire® Network Topologies
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2.5.3 1 - Wire® Network Limitation
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with a single selected slave. If an
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user group was founded in March of
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protocol on multiple media for maxi
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ecessive bit and the monitored stat
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specification: Start-Of-Frame, Arbi
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Cyclic Redundancy Check (CRC) Field
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Arbitration FieldThe Arbitration Fi
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SOF SOF Bit 28 Bit 27 Arbitration f
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Afterwards it starts transmitting s
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Figure 3.9 Structure of the Interfr
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error occurs, an Error Frame is gen
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Table 3.4 Error Flag Output Timing
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3.5.2 Error-Passive A node becomes
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where tNBT is the Nominal Bit Time
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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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Page 127 and 128: est-case latency occurs when the bu
Page 129 and 130: to break the 1 - Wire® network int
Page 131 and 132: ow, is most critical for power deli
Page 133 and 134: computations have device-specific p
Page 135 and 136: Table 4.7 Example results with N 2
Page 137 and 138: 4.3.5 Communication Speed Different
Page 139 and 140: anging” a port pin on a microproc
Page 141 and 142: From Figure 5.1, the block I/O pins
Page 143 and 144: 5.2.2 Command Register In addition
Page 145 and 146: specifies the selected bit value to
Page 147 and 148: with i > m. This process is repeate
Page 149 and 150: Figure 5.6 Interrupt Register. OW_
Page 151 and 152: the INTR pin will be pulled high si
Page 153 and 154: master reset occurs. Table 5.2 show
Page 155 and 156: EN_FOW: Enable Force One Wire. Sett
Page 157 and 158: READ_ROM - Used to read the 64-bit
Page 159 and 160: 5.2.8.1 Single Search ROM (single_s
Page 161 and 162: 5.2.8.3 Scratchpad Memory (scratchp
Page 163 and 164: 5.2.8.4 Command Recognition (cmd_re
Page 165 and 166: TBF - The Transmit Buffer provides
Page 167 and 168: compensate for the propagation dela
Page 169 and 170: Figure 5.15 CAN Module memory map [
Page 171 and 172: ‘0’, fast speed mode will be us
Page 173 and 174: COMP-SEL: Comparator Select. When t
Page 175: Figure 5.18 CAN Status Register. B
Page 179 and 180: Acceptance Mask Registers (accepted
Page 181 and 182: SJW1, SJW0: Synchronization Jump Wi
Page 183 and 184: TSEG22 - TSEG10: Time Segment Bits.
Page 185 and 186: The transmit clock (ttxclk) is used
Page 187 and 188: 5.3.13 CAN Module Transmit Buffer I
Page 189 and 190: Figure 5.28 CAN Transmit Data Segme
Page 191 and 192: 5.3.20 CAN Node Overview As stated
Page 193 and 194: Read Digital InputsRead the value o
Page 195 and 196: the clock high time is either 5 µs
Page 197 and 198: Yes Perform A/D Conversion on AN0 W
Page 199 and 200: and GP2 and GP5 as outputs. With th
Page 201 and 202: external INT pin, and then branches
Page 203 and 204: Read MCP2515 Rx Buffer for Digital
Page 205 and 206: When a valid message is received, t
Page 207 and 208: Table 5.19 Resource Utilization. Re
Page 209 and 210: For this test, only one CAN node wa
Page 211 and 212: an Error Frame to be generated. Aft
Page 213 and 214: messages, acknowledge messages, or
Page 215 and 216: 5.3.21.4 Send Basic Frame Test (sen
Page 217 and 218: going from one node to 30 nodes (se
Page 219 and 220: Table 6.1 Resource Utilization. Rev
Page 221 and 222: 6.2.1 Test Verification and Overvie
Page 223 and 224: has read access to this register. T
Page 225 and 226: 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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