IDEC MicroSmart - Manual (Page 205)

7: B ASIC I NSTRUCTIONS
« FC4A M ICRO S MART U SER ’ S M ANUAL » 7-21
Bidirectional Shift Register
A bidirectional shift register can be created by first programming the SFR instruction as detailed in the Forward Shift Reg-
ister section on page 7-18. Next, the SFRN instruction is programed as detailed in the Reverse Shift Register section on
page 7-20.
Structural Diagram
I3
I1
R22
Reset
Data
I2
Pulse
R23 R24 R25
For ward Shifting
Last Bit: R22 # of Bits: 6
R26 R27
Note: Output is initiated only for those bits highlighted in bold print.
I4
I6
I5
Reset
Data
Pulse
First Bit: R22 # of Bits: 6
Reverse Shifting
Ladder Diagram
I1
I2
SFR R22
6
I3
Reset
Pulse
Data
I4
I5
SFRN R22
6
I6
Reset
Pulse
Data
R23
R24
R26
Instruction Data
LOD
LOD
LOD
SFR
LOD
LOD
LOD
SFRN
LOD
OUT
LOD
OUT
LOD
OUT
I1
I2
I3
R22
6
I4
I5
I6
R22
6
R23
Q0
R24
Q1
R26
Q2
Program List
Q0
Q2
Q1