MPC850 Family User’s Manual
CONTENTS
Paragraph
Number
Title
Page
Number
15.4.8 Memory Periodic Timer Prescaler Register (MPTPR)............................... 15–18
15.5 General-Purpose Chip-Select Machine (GPCM)............................................ 15–18
15.5.1 Timing Configuration ................................................................................. 15–19
15.5.1.1 Chip-Select Assertion Timing ................................................................ 15–20
15.5.1.2 Chip-Select and Write Enable Deassertion Timing................................ 15–21
15.5.1.3 Relaxed Timing ...................................................................................... 15–23
15.5.1.4 Output Enable (OE) Timing ................................................................... 15–26
15.5.1.5 Programmable Wait State Configuration................................................ 15–26
15.5.1.6 Extended Hold Time on Read Accesses................................................. 15–26
15.5.2 Boot Chip-Select Operation........................................................................ 15–28
15.5.3 External Asynchronous Master Support ..................................................... 15–29
15.5.4 Special Case: Bursting with External Transfer Acknowledge: .................. 15–30
15.6 User-Programmable Machines (UPMs).......................................................... 15–31
15.6.1 Requests ...................................................................................................... 15–32
15.6.1.1 Internal/External Memory Access Requests........................................... 15–32
15.6.1.2 UPM Periodic Timer Requests ............................................................... 15–33
15.6.1.3 Software Requests—MCR run Command.............................................. 15–33
15.6.1.4 Exception Requests................................................................................. 15–33
15.6.2 Programming the UPM............................................................................... 15–34
15.6.3 Control Signal Generation Timing ............................................................. 15–34
15.6.4 The RAM Array.......................................................................................... 15–37
15.6.4.1 RAM Words............................................................................................ 15–37
15.6.4.2 Chip-Select Signals (CSTx).................................................................... 15–41
15.6.4.3 Byte-Select Signals (BSTx).................................................................... 15–42
15.6.4.4 General-Purpose Signals (GxTx, G0x)................................................... 15–43
15.6.4.5 Loop Control (LOOP)............................................................................. 15–44
15.6.4.6 Exception Pattern Entry (EXEN)............................................................ 15–45
15.6.4.7 Address Multiplexing (AMX) ................................................................ 15–45
15.6.4.8 Transfer Acknowledge and Data Sample Control (UTA, DLT3) .......... 15–50
15.6.4.9 Disable Timer Mechanism (TODT) ....................................................... 15–51
15.6.4.10 The Last Word (LAST) .......................................................................... 15–51
15.6.4.11 The Wait Mechanism (WAEN) .............................................................. 15–51
15.6.4.11.1 Internal and External Synchronous Masters ....................................... 15–51
15.6.4.11.2 External Asynchronous Masters......................................................... 15–52
15.7 Handling Devices with Slow or Variable Access Times ................................ 15–53
15.7.1 Hierarchical Bus Interface Example ........................................................... 15–54
15.7.2 Slow Devices Example ............................................................................... 15–54
15.8 External Master Support ................................................................................. 15–54
15.8.1 Synchronous External Masters ................................................................... 15–54
15.8.2 Asynchronous External Masters ................................................................. 15–55
15.8.3 Special Case: Address Type Signals for External Masters......................... 15–55
15.8.4 UPM Features Supporting External Masters .............................................. 15–55
15.8.4.1 Address Incrementing for External Synchronous Bursting Masters ...... 15–55