Page 378 - Embedded Microprocessor Systems Real World Design
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schematic representation  of, 213f   timers, 246
                      semaphore use, 215-216             when to use, 251
                    dynamic. see DRAM                  Reference voltage, 103-104
                    estimation of, 7                   Refresh cycle
                    ICs, 65                              DRAM, 52-53
                    microprocessor selection and, 7      internal, 52
                    nonvolatile, 45, 48                  microprocessor and, conflicts between,
                    requirements needed, 7                    53
                    restrictions on, 137                 self-refresh capability, 53
                    static, 45                         Registers
                    types of, 45                         for communication in multiprocessor
                    usage of, 7                               systems, 205-21 1
                  RAS access time, 49                    context switching, 157
                  RAS/CAS precharge time, 50             debugging, 193-194,  282
                  RAS hold time, 50                      D-type, 321, 322f
                  -RD  signal, 98                        hardware debug, 258
                  Read modify write (rmv) cycle, 51      input capture, 113
                  Real-time events, 9-10                 packaging of, 321
                  Real-time operating system             saved on stack, 156
                    applicability of, 251                segment, 285
                    application using, 267-269           types of, 320-321
                    buffers, 243                       Reloading timer, 108f, 109
                    challenges associated with, 251    Requirements definition
                    characteristics of, 237-238          description of, 3-5
                    communication in, 247-248,  251      example of, 2627
                    costs of, 251                      RF energy
                    debugging, 252                       emissions control, 87-88
                    description of, 130                  radiated susceptibility, 89
                    DOS emulation, 260-261               regulations on, 86
                    full operating system, 238         ROM
                    functions supported by, 238          characteristics of, 42
                    hardware effects, 250                debugging information written to,
                    interrupts and, 247                       175-1 76
                   kernel, 237, 251                     definition of, 42
                   memory                               DOS in, 260
                     management of, 244-245             emulators, 193
                     requirements, 251                  estimating requirements for, 7
                   microcontrollers, 252                ICs, 65
                   microprocessors, 10-1 1, 251-252     mask charges for producing, 13
                   multitasking                         microprocessor selection and, 7-8
                     definition of, 238                 trace data for debugging read from,
                     eventdriven scheduling, 240-241          1761 77
                     preemptive scheduling, 239, 241, 251   ROM 8031, 13
                     tasks activation and deactivation,   ROMability
                         239-240                        definition of, 12
                     time slicing and, 238, 239f        microprocessor selection and, 12-1 4
                   overview of, 235-238               Round-robin scheduling, 235
                   preemption considerations, 248-250   Row address hold time, 49
                   resource management, 245-246       Row address setup time, 49
                   scheduling in, 236                 Row address strobe, 45
                   tasks in                           RTOS. see Real-time operating system
                     communication between, 243-244
                     scheduling of, 244               Scheduling, in real-time operating system
                     tracking of, 242                   eventdriven, 240-241


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