W77E058A Datasheet, PDF (40/87 Pages) Winbond – 8-BIT MICROCONTROLLER

W77E058A
Machine cycles in standard 8032 = 10 + (26 * CNT)
Machine cycles in W77E058 = 10 + (26 * CNT)
If CNT = 50
Clock cycles in standard 8032= ((10 + (26 *50)) * 12 = (10 + 1300) * 12 = 15720
Clock cycles in W77E058 = ((10 + (26 * 50)) * 4 = (10 + 1300) * 4 = 5240
Block Move with Two Data Pointers in W77E058:
; 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
Machine Cycles of W77E058
#
MOV R2, #CNT
; Load R2 with the count value
2
MOV DPS, #00h ; Clear DPS to point to DPTR
2
MOV DPTR, #DHDL ; Load DPTR with Destination address
3
INC DPS
; Set DPS to point to DPTR1
2
MOV DPTR, #SHSL ; Load DPTR1 with Source address
3
LOOP:
MOVX A, @DPTR ; Get data from Source block
2
INC DPTR
; Increment source address
2
DEC DPS
; Clear DPS to point to DPTR
2
MOVX @DPTR, A ; Write data to Destination
2
INC DPTR
; Increment destination address
2
INC DPS
; Set DPS to point to DPTR1
2
DJNZ R2, LOOP ; Check if all done
3
Machine cycles in W77E058 = 12 + (15 * CNT)
If CNT = 50
Clock cycles in W77E058 = (12 + (15 * 50)) * 4 = (12 + 750) * 4 = 3048
We can see that in the first program the standard 8032 takes 15720 cycles, while the W77E058 takes
only 5240 cycles for the same code. In the second program, written for the W77E058, program
execution requires only 3048 clock cycles. If the size of the block is increased then the saving is even
greater.
8.3 External Data Memory Access Timing
The timing for the MOVX instruction is another feature of the W77E058. In the standard 8032, the
MOVX instruction has a fixed execution time of 2 machine cycles. However in the W77E058, 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
W77E058 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
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