I am facing a aproblem when trying to configure the PLL clock in order to set the CPU clock to 50 Mhz
I am using an external Quartz of 8 Mhz and the following setup program:
;*******************************************************
; Set PLL Speed
Set_pll_clock:
mov.b #0FFH,prcr ; Enable write to control registers
mov.b #080H,prcr2 ; Enable write to CM3 register
mov.b #0AAH,prr ; Enable write to CCR, FMCR, PBC register
bclr pm21 ; Enable clock change
mov.b #008H,cm0 ; System clock control register 0
mov.b #020H,cm1 ; System clock control register 1
mov.b #000H,cm2 ; Oscillation stop detect register
mov.b #002H,cm3 ; Low speed mode clock control register
mov.b #000H,tcspr ; Count source prescaler register
mov.b #080H,tcspr ; Count source prescaler register
mov.b #000H,cpsrf ; Clock prescaler reset register
mov.w #0A0DH,pbc ; Peripheral bus control register
; value depends on setting of CCR register
mov.b #013H,ccr ; Clock control register
mov.b #01FH,ccr ; Clock control register
mov.b #0FFH,prcr
mov.b #004H,plc0 ; PLL control register 0
mov.b #001H,plc1 ; PLL control register 1
bclr seo ; PLL mode
bclr bcs ; Base clock source is PLL
mov.b #020H,pm3 ; Peripheral clock = PLL/6
bset pm21 ; Disable clock change
mov.b #000H,prcr
rts
but can never the desired clock frequency of 100Mhz for the PLL
Thks in advance for your help
I forgot to thank you for your usual help
Best regards