SyncMOS Technologies International, Inc.
SM8958A
8-Bits Micro-controller
With 32KB flash & 1KB RAM embedded
N = BRM[2:0]
000
Number of SPWM cycles inserted in an 8-cycle frame
0
1
2
3
4
5
6
7
001
010
011
100
101
110
111
Example of SPWM timing diagram:
MOV SPWMC , #03H
MOV SPWMD0 , #83H
MOV P1CON , #08H
; Set output frequency (Divider = 16)
; SPWMD0[4:0]=10h (=16T high, 16T low), BRM[2:0] = 3
; Enable P1.3 as SPWM output pin
(narrow pulse inserted by BRM0[2:0] setting, here BRM0[2:0]=3)
SPWM clock = 1 / T = Fosc / 2^(SPFS[1:0]+1)
The SPWM output cycle frame frequency = SPWM clock / 32 = [Fosc/2^(SPFS[1:0]+1)]/32
If user use Fosc=20MHz, SPFS[1:0] of SPWMC=#03H, then
SPWM clock = 20MHz/2^4 = 20MHz/16 = 1.25MHz
SPWM output cycle frame frequency = (20MHz/2^4)/32=39.1KHz
Specifications subject to change without notice contact your sales representatives for the most recent information.
Ver 2.1 SM8958A 08/2006
13
SYNCMOS [ SYNCMOS TECHNOLOGIES,INC ]
