/**
* Calculate the necessary values in order to have the peripheral
* clock running at the desired frequency. As this value is only a
* divider, this normally requires a call to
* SystemClocksCalcCpuClockSettings() before, because the CPU
* frequency is needed to find the divider value.
*
* @see system.c::SystemConfig()
*
* @return Nothing (the result is put into the struct)
*/
void SystemClocksCalcPeripheralClockSettings(SystemClocksSettings *s,
uint32_t peripheralFrequency)
{
#ifdef EXTENDED_TEST_CASE
s->error = Error_None;
#endif
if (peripheralFrequency > CPUCOREMAXFREQUENCY)
{
peripheralFrequency = CPUCOREMAXFREQUENCY;
#ifdef EXTENDED_TEST_CASE
s->error = Error_RequestedFrequencyTooHigh;
#endif
}
const uint32_t cpuFrequency = SystemClocksGetCpuFrequency(s);
uint8_t i;
for (i = 0; i < pbDivsCount; i++)
{
if (cpuFrequency == peripheralFrequency * pbDivs[i])
{
s->PBDIV = i;
// Match found
return;
}
}
// No match: Use default value
s->PBDIV = 0; // /1
#ifdef EXTENDED_TEST_CASE
s->error = Error_NoCombinationFound;
#endif
}
/**
* Write the clock settings into the registers; this effectively applies the
* new settings, and will change the CPU frequency, peripheral
* frequency, and the number of flash wait states.
*
* This normally requires a call to
* SystemClocksCalcCpuClockSettings(), and
* SystemClocksCalcPeripheralClockSettings() before.
*
* @see system.c::SystemConfig()
*
* @return Nothing
*/
void SystemClocksWriteSettings(const SystemClocksSettings *s)
{
SystemUnlock();
/**
* @page 186
*
* PIC32MX Family Clock Diagram
*
* @page 189
*
* OSCCON: Oscillator Control Register
*/
/*
* bit 10-8 NOSC<2:0>: New Oscillator Selection bits
* 011 = Primary Oscillator with PLL module (XTPLL, HSPLL or ECPLL)
*/
OSCCONbits.NOSC = POSCPLL;
/*
* bit 29-27 PLLODIV<2:0>: Output Divider for PLL
*/
OSCCONbits.PLLODIV = s->PLLODIV;
/*
* bit 18-16 PLLMULT<2:0>: PLL Multiplier bits
*/
OSCCONbits.PLLMULT = s->PLLMULT;
/*
* bit 0 OSWEN: Oscillator Switch Enable bit
* 1 = Initiate an osc switch to selection specified by NOSC2:NOSC0 bits
* 0 = Oscillator switch is complete
*/
OSCCONbits.OSWEN = 1;
// Busy wait until osc switch has been completed
while (OSCCONbits.OSWEN == 1)
{
asm("nop");
}
/*
* bit 20-19 PBDIV<1:0>: Peripheral Bus Clock Divisor
*/
OSCCONbits.PBDIV = s->PBDIV;
// Set wait states
#if !defined(PIC32_PINGUINO_220) && \
!defined(PINGUINO32MX220) && \
!defined(PINGUINO32MX250) && \
!defined(PINGUINO32MX270)
CHECON = (SystemClocksGetCpuFrequency(s) / 20) - 1; // FlashWaitStates
#endif
//
SystemLock();
}
u32 GetSystemClock(void)
{
SystemClocksSettings s;
SystemClocksReadSettings(&s);
return SystemClocksGetCpuFrequency(&s);
}
/**
* Calculates the peripheral clock frequency based on the values which
* are passed in. This normally requires a call to
* SystemClocksReadSettings() before.
*
* @see system.c::GetPeripheralClock()
*
* @return The peripheral clock frequency
*/
uint32_t SystemClocksGetPeripheralFrequency(const SystemClocksSettings *s)
{
return SystemClocksGetCpuFrequency(s) / pbDivs[s->PBDIV];
}
