ST92185B STMicroelectronics, ST92185B Datasheet - Page 133

• Manufacturer Part Number: ST92185B
• Description: 16k/24k/32k Rom Hcmos Mcu With On-screen-display
• Manufacturer: STMicroelectronics

7.4.10 Application Software Examples
Before starting an OSD Display, it is very important to start all the internal clock/timings
To understand the software routines given below, make a thorough study of the chapters on the Reset
and Clock Control Unit (RCCU) and the TDSRAM Interface.
Initialization of the Internal Clock
;=========================================================================
;
;=========================================================================
CLOCKS::
;--------- CPU MAIN CLOCK ------------
time_stab1:
;=========================================================================
;
;=========================================================================
(external)
;=========================================================================
;
;=========================================================================
;
MAIN CLOCK INIT
spp #TCCR_PG; Timings & clock Controller registers page
ld MCCR,#0x05; program the frequency multiplier down
ld MCCR,#0x85; enable the freq. multiplier
srp #BK20
ldw rr0,#0x2FFF;
decw rr0; change CPU source clock & wait clock stabilization
cpw rr0,#0x00;
jxnz time_stab1;
ld MCCR,#0xC5 ; select the freq. multiplier as main clock
pop ppr
SYNCHRO START
spp #SYCR_PG
ld CSYCTR,#000h; R243, Hsync and Vsync from deflection part
ld CSYSUR,#0C4h; R242 Sync Controller Set-up register
DISPLAY PIXEL CLOCK
spp #TCCR_PG; Timings & clock Controller registers page
ld SKCCR, #0x09; FE, Skew clock control register
; C K M A I N
; page 39 or 27
; counter in the feed-back loop (253 =FD)
; freq=(5+1)*2 =12Mhz
; freq=(7+1)*2 =16Mhz
; freq=(8+1)*2 =18Mhz
; for frequency multiplier stabilization
; Standard mode, Positive polarity of Hsync & Vsync
; delay on Hsync/Vsync HSF(3:0)=9
; set page pointer to page 39 decimal
; program the frequency multiplier down
; counter in the feed-back loop
; set page pointer to page 23h or 35 decimal
provided by the freq. multplier
ST92185B - ON SCREEN DISPLAY (OSD)
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