69
RAM Self-Test
This routine performs a simple alternating 0/1 test on RAM locations R3–R255 by writing an AA,55 pattern
to this RAM space and then checking the RAM for this pattern. The inverted pattern is then written to RAM
and rechecked. Finally, the entire RAM is cleared. If an error is found, a bit is set in the flag register. The
error flag bit should be cleared before the routine is started.
Table 1. Register Values
Register
Before
After: No Error
After: Error
A
XX
0
?
B
XX
0
?
FLAG
XX
0
Bit 0 = 1
NOTE:
•
Passing data: none
•
Registers affected: all
•
Ending data: all registers = 0; bit 0 in FLAG = 1 if error was found
Routine
.TEXT 7000H ;Absolute start address
FLAG .EQU R2 ;Error register
MOV #55h,A ;Start RAM fill with 55h
FILLR MOV #0FDh,B ;Set RAM start address – 3
;(don’t change registers A, B, or R2)
FILL1 MOV A,*2[B] ;Fill RAM with AA to 55 pattern
RR A ;Change to beginning number
DJNZ B,FILL1 ;Fill entire RAM with pattern
RR A ;Change to beginning number
MOV #0FDh,B ;Refresh index
COMPAR CMP *2[B],A ;Check for errors
JNE ERROR ;Exit if values don’t match
RR A ;Change from 55 to AA to 55
DJNZ B,COMPAR ;Check the entire RAM
CLRC ;Is reg A now 55, AA or 00?
JN FILLR ;=AA, change to opposite pattern
JZ EXIT ;=00,
FILL0 CLR A ;=55,clear the ram now
JMP FILLR ;Repeat the fill and check routine
ERROR OR #1,FLAG ;Set bit zero in the flag
;register
EXIT .EQU $ ;Continue program here
*
Summary of Contents for TMS370 Series
Page 1: ...TMS370 Microcontroller Family Application Book 1996 8 Bit Microcontroller Family ...
Page 2: ...Printed in U S A February 1996 SPNA017 ...
Page 3: ...1996 Application TMS370 Microcontroller Family Book ...
Page 20: ...1 Part I Introduction ...
Page 21: ...2 ...
Page 22: ...3 Introduction Microcontroller Products Semiconductor Group Texas Instruments ...
Page 23: ...4 ...
Page 25: ...6 ...
Page 27: ...8 ...
Page 29: ...10 ...
Page 31: ...12 ...
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Page 41: ...22 ...
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Page 47: ...28 ...
Page 49: ...30 ...
Page 81: ...62 ...
Page 82: ...63 Clear RAM Microcontroller Products Semiconductor Group Texas Instruments ...
Page 83: ...64 ...
Page 85: ...66 ...
Page 86: ...67 RAM Self Test on the TMS370 Microcontroller Products Semiconductor Group Texas Instruments ...
Page 87: ...68 ...
Page 89: ...70 ...
Page 90: ...71 ROM Checksum on the TMS370 Microcontroller Products Semiconductor Group Texas Instruments ...
Page 91: ...72 ...
Page 95: ...76 ...
Page 97: ...78 ...
Page 98: ...79 Bubble Sort With the TMS370 Microcontroller Products Semiconductor Group Texas Instruments ...
Page 99: ...80 ...
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Page 324: ...305 T1PWM Set Up Routines Microcontroller Products Semiconductor Group Texas Instruments ...
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Page 396: ...377 PACT Command Macros Microcontroller Products Semiconductor Group Texas Instruments ...
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Page 492: ...473 Part V External Memory Expansion Examples ...
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