Experiment 2

1
Experiment 2 PIC Program Execution Built-In
Self-Test
2
Basic Experiment
3
Additional Functionality
Use the current instruction set from Lab 1 with
additional functionality to execute a cycle
accurate PIC program out of Instruction Memory.
Need to add the idea of sequential logic to the
design with a clock. PIC instructions are
executed on a single clock cycle, this
includes 1) Performing the operation 2)
Storing the result Lab 1 only performed the
operation need to store result from R output
of ALU into the appropriate register (either W or
in the register file RF) before the next program
instruction clock cycle. Must decode destination
address to determine appropriate storage location
4
Additional Functionality Cont.
Three additional functions related to moving
and storing registers 1) MOVLW Move
Literal to Working Register (W) 12 bit Opcode
1100 kkkk kkkk, where kkkkkkkk is the value
to write to the W Register. 2) MOVWF
Move W to one of the Memory Registers (MR) in the
Register File 12 bit Opcode 0000 001f ffff,
where fffff is the address of the register to
write to. 3) MOVF Move from MR to W 12
bit Opcode 0010 00df ffff, where fffff is
the address of the register whose contents are
to be written to W, IF d is 0. The d 1
case will not be used.
5
Dout
Current instruction
ROM
Addr In
Clock
8
Program Sequencer
ALU
W
W
Load_W_en
?
8
Dest Decode
dest addr
R
Load_R_en310
R0 R1 R2 . . . R31
RF
Clock
8
Register File
Lab 2 Block Diagram
6
Extra Credit Assignment
7
Bonus BILBO Implementation(Built In Logic Block
Observer)
Implement registers as BILBOs with added
abilities
BILBO Block Diagram
Offers four separate functionalities, depending
on the values of (B1,B2) 1) Serial Scan
Mode (0,0) 2) Pattern Generator (0,1)
3) Normal Mode (1,0) 4) MISR Multiple
Input Signature Register (1,1)
8
Example BILBO Usage

• SI Scan In
• SO Scan Out
• Characteristic polynomial 1 x xn
• CUTs A and C BILBO1 is MISR, BILBO2 is LFSR
• CUT B BILBO1 is LFSR, BILBO2 is MISR

9
BILBO Serial Scan Mode

• B1 B2 00
• Dark lines show enabled data paths

10
BILBO LFSR Pattern Generator Mode

• B1 B2 01

11
BILBO in D FF (Normal) Mode

• B1 B2 10

12
BILBO in MISR Mode

• B1 B2 11