W77L32 Datasheet, PDF (39/76 Pages) Winbond – 8-BIT MICROCONTROLLER

W77L32/W77L032A/W77M032A
Machine cycles in standard 8032 = 10 + (26 * CNT)
Machine cycles in W77L032 = 10 + (26 * CNT)
If CNT = 50
Clock cycles in standard 8032= ((10 + (26 *50)) * 12 = (10 + 1300) * 12 = 15720
Clock cycles in W77L032 = ((10 + (26 * 50)) * 4 = (10 + 1300) * 4 = 5240
Block Move with Two Data Pointers in W77L032:
; SH and SL are the high and low bytes of Source Address
; DH and DL are the high and low bytes of Destination Address
; CNT is the number of bytes to be moved
MOV R2, #CNT
; Load R2 with the count value
MOV DPS, #00h ; Clear DPS to point to DPTR
MOV DPTR, #DHDL ; Load DPTR with Destination address
INC DPS
; Set DPS to point to DPTR1
MOV DPTR, #SHSL ; Load DPTR1 with Source address
LOOP:
MOVX A, @DPTR ; Get data from Source block
INC DPTR
DEC DPS
; Increment source address
; Clear DPS to point to DPTR
MOVX @DPTR, A ; Write data to Destination
INC DPTR
; Increment destination address
INC DPS
DJNZ R2, LOOP
; Set DPS to point to DPTR1
; Check if all done
Machine cycles of W77L032
#
2
2
3
2
3
2
2
2
2
2
2
3
Machine cycles in W77L032 = 12 + (15 * CNT)
If CNT = 50
Clock cycles in W77L032 = (12 + (15 * 50)) * 4 = (12 + 750) * 4 = 3048
We can see that in the first program the standard 8032 takes 15720 cycles, while the W77L032 takes
only 5240 cycles for the same code. In the second program, written for the W77L032, program
execution requires only 3048 clock cycles. If the size of the block is increased then the saving is even
greater.
External Data Memory Access Timing
The timing for the MOVX instruction is another feature of the W77L032. In the standard 8032, the
MOVX instruction has a fixed execution time of 2 machine cycles. However in the W77L032, the
duration of the access can be varied by the user.
The instruction starts off as a normal op-code fetch of 4 clocks. In the next machine cycle, the
W77L032 puts out the address of the external Data Memory and the actual access occurs here. The
user can change the duration of this access time by setting the STRETCH value. The Clock Control
SFR (CKCON) has three bits that control the stretch value. These three bits are M2-0 (bits 2-0 of
CKCON). These three bits give the user 8 different access time options. The stretch can be varied
from 0 to 7, resulting in MOVX instructions that last from 2 to 9 machine cycles in length. Note that the
stretching of the instruction only results in the elongation of the MOVX instruction, as if the state of the
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Publication Release Date: April 17, 2007
Revision A6