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

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e received may be lost. To reduce the requirements on the CPU, two receive buffers (RBF0 and RBF1) are implemented. While one receive buffer is allocated to the CPU, the BSP may write to the other buffer. RBF0 and RBF1 are each 10 bytes long and hold the Identifier (1 byte), the Control Field (1 byte) and the Data Field (maximum length of 8 bytes). The BSP only writes into a receive buffer when the message being received or transmitted has an Identifier which passes the Acceptance Filter. BSP – This is a sequencer controlling the data stream between the Transmit and Receive Buffers (parallel data) and the CAN (serial data). The BSP also controls the Transceive Logic (TCL) and the Error Management Logic (EML) such that the processes of reception, arbitration, transmission and error signaling are performed according to the protocol and the bus rules. The BSP also provides signals to the IML indicating when a Receive Buffer contains a valid message and when the Transmit Buffer is no longer required after a successful transmission. The automatic retransmission of messages, which have been corrupted by noise or other external conditions on the bus line, is effectively handled by the BSP. BTL – The Bit Timing Logic block monitors the CAN bus line using an input comparator and handles the CAN bus line related bit timing. The BTL synchronizes on a recessive-to-dominant bus line transition at the Start of Frame (hard synchronization), and resynchronizes on further transitions during reception of a frame (soft synchronization). A programmable control bit in the CPU determines which edges are used for resynchronization. The BTL also provides programmable time segments to 141
compensate for the propagation delay times and phase shifts and to define the sampling time and the number of samples (1 or 3) within the bus time slot. TCL – The Transceive Logic unit is a generic term for a group of logic elements consisting of a programmable output driver, bit stuff logic, CRC logic and the transmit shift register. The coordination of these components is controlled by the BSP. EML – The Error Management Logic unit is responsible for the error confinement of the CAN module. It receives notification of errors from the BSP and then informs the BSP, TCL, and IML about error statistics [98]. Up to the message level, the CAN module presented here is totally compatible with CAN Specification 2.0 Part A. The functional differences are related to the object layer only. Whereas a full CAN Controller provides dedicated hardware for handling a set of messages, the implementation presented here is restricted to receiving and/or transmitting messages on a message by message basis. Also, the controller presented here will never initiate an Overload Frame. If the module starts to receive a valid message (i.e., one that passes the Acceptance Filter) and there is no receive buffer available for it, then the Overrun Flag in the CPU Status Register will be set. The module, will however, respond to Overload Frames generated by other CAN nodes, as required by the CAN protocol specifications. To be able to function as a serial communication interface, the CAN Controller Module, shown in Figure 5.13, itself has to be supplemented by an additional module, the Controller Interface Logic Unit (CIL). The CIL is an integral part of any CAN system or stand-alone CAN Controller. The CIL, shown in Figure 5.14, links the CAN Module to the 142
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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
Page 115 and 116: Recently, a technique has been prop
Page 117 and 118: procedure, then the address claim p
Page 119 and 120: paradigms are prevalent in the desi
Page 121 and 122: systems possess a higher flexibilit
Page 123 and 124: fixed identifier and hence a fixed
Page 125 and 126: 348sm Cm 47 8 smbit 11-bit hea
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: TBF - The Transmit Buffer provides
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 and 176: Figure 5.18 CAN Status Register. B
Page 177 and 178: that buffer is given to the CPU and
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
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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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