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Arduboy2
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Fix setting CPU clock to 8MHz 

A dedicated #define is used.
The PLL prescaler for USB is readjusted.
This commit is contained in:
Scott Allen 2016-04-01 16:27:38 -04:00
parent f6e7ee40e7
commit ded48cef81
2 changed files with 13 additions and 8 deletions
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19
src/core/core.cpp
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@ -93,9 +93,10 @@ ArduboyCore::ArduboyCore() {}
void ArduboyCore::boot() void ArduboyCore::boot()
{ {
#if F_CPU == 8000000L #ifdef ARDUBOY_SET_CPU_8MHZ
bootCPUSpeed(); // ARDUBOY_SET_CPU_8MHZ will be set by the IDE using boards.txt
#endif setCPUSpeed8MHz();
#endif
SPI.begin(); SPI.begin();
bootPins(); bootPins();
@ -109,15 +110,19 @@ void ArduboyCore::boot()
bootPowerSaving(); bootPowerSaving();
} }
#if F_CPU == 8000000L #ifdef ARDUBOY_SET_CPU_8MHZ
// if we're compiling for 8Mhz we need to slow the CPU down because the // If we're compiling for 8MHz we need to slow the CPU down because the
// hardware clock on the Arduboy is 16MHz // hardware clock on the Arduboy is 16MHz.
void ArduboyCore::bootCPUSpeed() // We also need to readjust the PLL prescaler because the Arduino USB code
// likely will have incorrectly set it for an 8MHz hardware clock.
void ArduboyCore::setCPUSpeed8MHz()
{ {
uint8_t oldSREG = SREG; uint8_t oldSREG = SREG;
cli(); // suspend interrupts cli(); // suspend interrupts
PLLCSR = _BV(PINDIV); // dissable the PLL and set prescale for 16MHz)
CLKPR = _BV(CLKPCE); // allow reprogramming clock CLKPR = _BV(CLKPCE); // allow reprogramming clock
CLKPR = 1; // set clock divisor to 2 (0b0001) CLKPR = 1; // set clock divisor to 2 (0b0001)
PLLCSR = _BV(PLLE) | _BV(PINDIV); // enable the PLL (with 16MHz prescale)
SREG = oldSREG; // restore interrupts SREG = oldSREG; // restore interrupts
} }
#endif #endif

2
src/core/core.h
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@ -283,9 +283,9 @@ protected:
void static inline safeMode() __attribute__((always_inline)); void static inline safeMode() __attribute__((always_inline));
// internals // internals
void static inline setCPUSpeed8MHz() __attribute__((always_inline));
void static inline bootOLED() __attribute__((always_inline)); void static inline bootOLED() __attribute__((always_inline));
void static inline bootPins() __attribute__((always_inline)); void static inline bootPins() __attribute__((always_inline));
void static inline bootCPUSpeed() __attribute__((always_inline));
void static inline bootPowerSaving() __attribute__((always_inline)); void static inline bootPowerSaving() __attribute__((always_inline));