45111 Datasheet, PDF (8/184 Pages) List of Unclassifed Manufacturers – 14-DAY MONEY BACK GUARANTEE

Table of Contents
15.2.2 Read-Modify-Write Considerations ..................................................................................................151
15.2.3 Register Map Structure .......................................................................................................................151
15.2.4 Special Function Registers..................................................................................................................153
15.2.5 IND – The Indirect Register ($00) ......................................................................................................153
15.2.6 Real Time Clock/Counter, WREG ($01)...........................................................................................153
15.2.7 PC – Program Counter ($02) ..............................................................................................................153
15.2.8 STATUS Register ($03)........................................................................................................................154
15.2.9 The FSR – File Select Register ($04) ...................................................................................................155
15.2.10 Direct Addressing................................................................................................................................156
15.2.11 Indirect Addressing.............................................................................................................................160
15.2.12 The Bank Instruction ...........................................................................................................................161
15.2.13 The Jump Instruction ..........................................................................................................................162
15.2.14 Jumping Across Pages.........................................................................................................................163
15.2.15 The Call Instruction.............................................................................................................................163
15.2.16 Calling Across Pages ...........................................................................................................................164
15.2.17 Returning from a subroutine..............................................................................................................164
15.2.18 The Stack...............................................................................................................................................165
15.2.19 The Push ...............................................................................................................................................165
15.2.20 The Pop .................................................................................................................................................166
15.2.21 Stack Overflow.....................................................................................................................................166
15.2.22 Stack Underflow ..................................................................................................................................166
15.2.23 Returns ..................................................................................................................................................166
15.3 Port Configuration Registers .............................................................................................................................167
15.3.1 Port A Registers ...................................................................................................................................167
15.3.1.1 TRIS_A – Data Direction Register......................................................................................167
15.3.1.2 LVL_A - TTL/CMOS Select Register ................................................................................167
15.3.1.3 PLP_A – Pull-Up Resistor Enable Register.......................................................................167
15.3.2 Port B Registers ....................................................................................................................................168
15.3.2.1 TRIS_B – Data Direction Register ......................................................................................168
15.3.2.2 LVL_B - TTL/CMOS Select Register.................................................................................168
15.3.2.3 PLP_B – Pull-Up Resistor Enable Register .......................................................................168
15.3.2.4 ST_B – Schmitt-Trigger Enable Register ...........................................................................169
15.3.2.5 WKEN_B – Wake Up Enable Register...............................................................................169
15.3.2.6 WKED_B – Wake Up Edge Select Register.......................................................................169
15.3.2.7 WKPND_B – MIWU Pending Register .............................................................................169
15.3.2.8 CMP_B – Comparator Enable Register .............................................................................170
15.3.3 Port C Registers....................................................................................................................................170
15.3.3.1 TRIS_C – Data Direction Register ......................................................................................170
15.3.3.2 LVL_C - TTL/CMOS Select Register.................................................................................170
15.3.3.3 PLP_C – Pull-Up Resistor Enable Register .......................................................................171
15.3.3.4 ST_C – Schmitt-Trigger Enable Register...........................................................................171
15.3.4 Port D and E Registers (SX48/52)......................................................................................................171
15.4 Control registers ..................................................................................................................................................171
15.4.1 Mode register (SX20/28).....................................................................................................................171
15.4.2 Mode register (SX48/52).....................................................................................................................173
Page 8 • SX-Key/Blitz Development System Manual 2.0 • Parallax, Inc.