Electronics America Computer Hardware User Manual

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Contents
10.4 OPERATIONS IN THE THREE-WIRE SERIAL I/O MODE ..................................................265
10.4.1 Basic Operation Timing ..........................................................................................265
10.4.2 Operation When Only Transmission Is Permitted...............................................267
10.4.3 Operation When Only Reception Is Permitted.....................................................267
10.4.4 Operation When Both Transmission and Reception Are Permitted .................267
10.4.5 Action to Be Taken When the Serial Clock and Shift Become Asynchronous .... 268
10.5 SBI MODE .............................................................................................................................268
10.5.1 Features of SBI .........................................................................................................268
10.5.2 Configuration of the Serial Interface.....................................................................270
10.5.3 Detecting an Address Match ..................................................................................272
10.5.4 Control Registers in SBI Mode...............................................................................272
10.6 SBI COMMUNICATION AND SIGNALS .............................................................................277
10.6.1 Bus Release Signal (REL) .......................................................................................277
10.6.2 Command Signal (CMD) ........................................................................................278
10.6.3 Address ....................................................................................................................278
10.6.4 Command and Data ................................................................................................279
10.6.5 Acknowledge Signal (ACK) ....................................................................................279
10.6.6 Busy Signal (BUSY) and Ready Signal (READY) ................................................280
10.6.7 Signals ......................................................................................................................280
10.6.8 Communication .......................................................................................................287
10.6.9 Releasing the Busy State .......................................................................................287
10.6.10 Setting Wake-Up .....................................................................................................287
10.6.11 Starting Transmission and Reception..................................................................287
10.7 NOTES ...................................................................................................................................292
CHAPTER 11 EDGE DETECTION FUNCTION .....................................................................................................293
11.1 EXTERNAL INTERRUPT MODE REGISTERS (INTM0, INTM1) .......................................293
11.2 EDGE DETECTION ON PIN P20 ..........................................................................................296
11.3 EDGE DETECTION ON PINS P21 TO P26 ..........................................................................297
11.4 NOTES ...................................................................................................................................298
CHAPTER 12 INTERRUPT FUNCTIONS ..............................................................................................................301
12.1 INTERRUPT REQUEST SOURCES......................................................................................302
12.1.1 Software Interrupt Request ...................................................................................302
12.1.2 Nonmaskable Interrupt Request ...........................................................................303
12.1.3 Maskable Interrupt Request ..................................................................................303
12.1.4 Selecting an Interrupt Source ...............................................................................303
12.2 INTERRUPT HANDLING CONTROL REGISTERS ..............................................................304
12.2.1 Interrupt Request Flag Register (IF0) ...................................................................305
12.2.2 Interrupt Mask Register (MK0) ..............................................................................306
12.2.3 Interrupt Service Mode Register (ISM0) ..............................................................306
12.2.4 Priority Specification Flag Register (PR0)............................................................306
12.2.5 Interrupt Status Register (IST) ..............................................................................307
12.2.6 Program Status Word (PSW) ................................................................................308
12.3 INTERRUPT HANDLING ......................................................................................................308
12.3.1 Accepting Software Interrupts ..............................................................................308
12.3.2 Accepting Nonmaskable Interrupts ......................................................................308
12.3.3 Accepting Maskable Interrupts .............................................................................311