STR752 RTC problem

[philipd]

Posted on August 05, 2010 at 05:04

Hi

I am having trouble getting my RTC to run of theCK_OSC4M / Up to now I have been using32 khz crystal oscillator but now need to use the internal clock at board space is an issue. Can anybody help asI can not see anything wrong with what I am doing. CKRTCBYP_BIT= 0x40000000// RTC oscillator bypass CKRTCSEL_BIT= 0x01000000// RTC Clock Select .. bit 25 = 0 bit 24 = 1 CKRTCSEL_MASK= 0xFCFFFFFF Code

Reset_Handler:// after a reset start here

ldr r0,=CFG_GLCONF_Addr ldr r1,[r0] orr r1,r1,FLASH_BURST_BIT str r1,[r0]

// --------------------------------------------------------------------------

// Description : Start the clocks and switch to the PLL // -------------------------------------------------------------------------- ldr r0,=MRCC_BASE_Addr// MCU Reset and Clock Control ldr r1,=MRCC_CLKCTL_Val ldr r2,[r0,MRCC_CLKCTL_OFS] ldr r5,=DIV_MASK mvn r6,r5 and r5,r1,r5 and r6,r2,r6 orr r5,r5,r6 str r5,[r0,MRCC_CLKCTL_OFS]

ldr r2,[r0,MRCC_CLKCTL_OFS]// wait presence of osc clk

bic r2,r2,NCKDF_BIT wait_osc_pres: str r2,[r0,MRCC_CLKCTL_OFS]// write 0 to NCKDF Flag ldr r1,[r0,MRCC_CLKCTL_OFS]// read NCKDF Flag ands r1,r1,NCKDF_BIT bne wait_osc_pres// if NCKDF Flag set to 1

wait_clk_stable:

ldr r1,[r0,MRCC_RFSR_OFS]// wait stable clock ands r1,r1,BCOUNTF_BIT beq wait_clk_stable

ldr r1,[r0,MRCC_CLKCTL_OFS]// switch CK_SYS to CK_OSC4M

orr r2,r1,CKSEL_BIT str r2,[r0,MRCC_CLKCTL_OFS]

ldr r1,=MRCC_CLKCTL_Val// setup PLL multiply factor .. note PLL is by default disabled

ldr r2,[r0, MRCC_CLKCTL_OFS]// load current CLKCTL value ldr r3,=MUL_MASK mvn r4,r3 and r3,r1,r3 and r4,r2,r4 orr r3,r3,r4 str r3,[r0,MRCC_CLKCTL_OFS]// load multiply value

ldr r1,[r0,MRCC_CLKCTL_OFS]// enable the PLL

orr r1,r1,PLL_EN_BIT str r1,[r0,MRCC_CLKCTL_OFS]

PLL_locking:

ldr r1,[r0,MRCC_CLKCTL_OFS]// wait for PLL to lock ands r1,r1,PLL_LOCK_BIT beq PLL_locking

ldr r1,[r0,MRCC_CLKCTL_OFS]// switch CK_SYS to CK_PLL1

bic r1,r1,CKSEL_BIT str r1,[r0,MRCC_CLKCTL_OFS]

// --------------------------------------------------------------------------

// Description : Start the RTC // -------------------------------------------------------------------------- ldr r1,[r0,MRCC_PWRCTRL_OFS] and r1,r1,CKRTCSEL_MASK orr r1,r1,CKRTCSEL_BIT str r1,[r0,MRCC_PWRCTRL_OFS]// enable internal 4mhz / 128 .. RTC clock.

// --------------------------------------------------------------------------

// Description : Initialize stack pointer registers // -------------------------------------------------------------------------- ldr r0,=End_of_RAM

msrCPSR_c,Mode_UNDEF|I_Bit|F_Bit// No interrupts

mov sp,r0 sub r0,r0,UNDEF_Stack_Size

msrCPSR_c,Mode_ABT|I_Bit|F_Bit// No interrupts

mov sp,r0 sub r0,r0,ABT_Stack_Size

msrCPSR_c,Mode_SVC|I_Bit|F_Bit// No interrupts

mov sp,r0 sub r0,r0,SVC_Stack_Size

msrCPSR_c,Mode_FIQ|I_Bit|F_Bit// No interrupts

mov sp,r0 sub r0,r0,FIQ_Stack_Size

msrCPSR_c,Mode_IRQ|I_Bit|F_Bit// No interrupts

mov sp,r0 sub r0,r0,IRQ_Stack_Size

msrCPSR_c,Mode_SYS|I_Bit|F_Bit// No interrupts

mov sp,r0

// **************************************************************************

// Now enter the C code // Note : use B not BL, because an application will never return this way // ************************************************************************** bMain str752-rtc