diff options
| -rw-r--r-- | bsp/drivers/fe300prci/fe300prci_driver.c | 85 | ||||
| -rw-r--r-- | bsp/drivers/fe300prci/fe300prci_driver.h | 16 |
2 files changed, 54 insertions, 47 deletions
diff --git a/bsp/drivers/fe300prci/fe300prci_driver.c b/bsp/drivers/fe300prci/fe300prci_driver.c index 8491554..5fb2c27 100644 --- a/bsp/drivers/fe300prci/fe300prci_driver.c +++ b/bsp/drivers/fe300prci/fe300prci_driver.c @@ -175,75 +175,74 @@ void PRCI_use_hfxosc(uint32_t finaldiv) // doesn't span the entire range of HFROSC settings. // It only adjusts the trim, which can span a hundred MHz or so. // This function does not check the legality of the PLL settings -// at all, ant it is quite possible to configure invalid PLL settings +// at all, and it is quite possible to configure invalid PLL settings // this way. // It returns the actual measured CPU frequency. uint32_t PRCI_set_hfrosctrim_for_f_cpu(uint32_t f_cpu, PRCI_freq_target target ) { - int hfrosctrim = 16; - PRCI_use_default_clocks(); - PRCI_use_pll(0, 0, 1, 31, 1, 1, 4, 16); + int hfrosctrim = 0; + int hfroscdiv = 4; + int prev_trim = 0; + + // In this function we use PLL settings which + // will give us a 32x multiplier from the output + // of the HFROSC source to the output of the + // PLL. We first measure our HFROSC to get the + // right trim, then finally use it as the PLL source. + // We should really check here that the f_cpu + // requested is something in the limit of the PLL. For + // now that is up to the user. + + uint32_t desired_hfrosc_freq = f_cpu / 32; + + PRCI_use_hfrosc(hfroscdiv, hfrosctrim); + // Ignore the first run (for icache reasons) - uint32_t cpu_freq = PRCI_measure_mcycle_freq(1000, RTC_FREQ); + uint32_t cpu_freq = PRCI_measure_mcycle_freq(1000, RTC_FREQ); + cpu_freq = PRCI_measure_mcycle_freq(1000, RTC_FREQ); - int prev_trim = hfrosctrim; - int prev_freq = cpu_freq; + uint32_t prev_freq = cpu_freq; - if (cpu_freq > F_CPU) { - while((cpu_freq > F_CPU) && (hfrosctrim > 0) ){ - prev_freq = cpu_freq; - prev_trim = hfrosctrim; - hfrosctrim--; - PRCI_use_pll(0, 0, 1, 31, 1, 1, 4, hfrosctrim ); - cpu_freq = PRCI_measure_mcycle_freq(1000, RTC_FREQ); - } - - // Check for over/undershoot - switch(target) { - case(PRCI_FREQ_CLOSEST): - if ((prev_freq - F_CPU) < (F_CPU - cpu_freq) && target == PRCI_FREQ_CLOSEST) { - PRCI_use_pll(0, 0, 1, 31, 1, 1, 4, prev_trim); - cpu_freq = PRCI_measure_mcycle_freq(1000, RTC_FREQ); - } - break; - case(PRCI_FREQ_OVERSHOOT): - PRCI_use_pll(0, 0, 1, 31, 1, 1, 4, prev_trim); - cpu_freq = PRCI_measure_mcycle_freq(1000, RTC_FREQ); - break; - //default: - // Do Nothing - } - - return cpu_freq; - } - - while(cpu_freq < F_CPU && hfrosctrim < 0x20) { - prev_freq = cpu_freq; + while ((cpu_freq < desired_hfrosc_freq) && hfrosctrim < 0x1F){ prev_trim = hfrosctrim; + prev_freq = cpu_freq; hfrosctrim ++; - PRCI_use_pll(0, 0, 1, 31, 1, 1, 4, hfrosctrim ); + PRCI_use_hfrosc(hfroscdiv, hfrosctrim); cpu_freq = PRCI_measure_mcycle_freq(1000, RTC_FREQ); - } + } + // We couldn't go low enough + if (prev_freq > desired_hfrosc_freq){ + PRCI_use_pll(0, 0, 1, 31, 1, 1, hfroscdiv, prev_trim); + cpu_freq = PRCI_measure_mcycle_freq(1000, RTC_FREQ); + return cpu_freq; + } + // We couldn't go high enough + if (cpu_freq < desired_hfrosc_freq){ + PRCI_use_pll(0, 0, 1, 31, 1, 1, hfroscdiv, prev_trim); + cpu_freq = PRCI_measure_mcycle_freq(1000, RTC_FREQ); + return cpu_freq; + } + // Check for over/undershoot switch(target) { case(PRCI_FREQ_CLOSEST): - if ((F_CPU - prev_freq) < (cpu_freq - F_CPU)) { - PRCI_use_pll(0, 0, 1, 31, 1, 1, 4, prev_trim); + if ((desired_hfrosc_freq - prev_freq) < (cpu_freq - desired_hfrosc_freq)) { + PRCI_use_pll(0, 0, 1, 31, 1, 1, hfroscdiv, prev_trim); cpu_freq = PRCI_measure_mcycle_freq(1000, RTC_FREQ); } break; case(PRCI_FREQ_UNDERSHOOT): - PRCI_use_pll(0, 0, 1, 31, 1, 1, 4, prev_trim); + PRCI_use_pll(0, 0, 1, 31, 1, 1, hfroscdiv, prev_trim); cpu_freq = PRCI_measure_mcycle_freq(1000, RTC_FREQ); break; //default: // Do Nothing } - + return cpu_freq; } diff --git a/bsp/drivers/fe300prci/fe300prci_driver.h b/bsp/drivers/fe300prci/fe300prci_driver.h index 243e6de..7100f46 100644 --- a/bsp/drivers/fe300prci/fe300prci_driver.h +++ b/bsp/drivers/fe300prci/fe300prci_driver.h @@ -54,15 +54,23 @@ void PRCI_use_pll(int refsel, int bypass, void PRCI_use_default_clocks(); /* This routine will adjust the HFROSC trim - * as the PLL clock source, measure the resulting - * frequency, and attempt to get close to the requested - * frequency. It returns the actual measured frequency. + * while using HFROSC as the clock source, + * measure the resulting frequency, then + * use it as the PLL clock source, + * in an attempt to get over, under, or close to the + * requested frequency. It returns the actual measured + * frequency. * * Note that the requested frequency must be within the * range supported by the PLL so not all values are * achievable with this function, and not all - * are guaranteed to actually work. + * are guaranteed to actually work. The PLL + * is rated higher than the hardware. + * + * There is no check on the desired f_cpu frequency, it + * is up to the user to specify something reasonable. */ + uint32_t PRCI_set_hfrosctrim_for_f_cpu(uint32_t f_cpu, PRCI_freq_target target); __END_DECLS |