djsundog/circuitpython
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

atmel-sam: Allow PWM to go up to cpu_frequency/2

Browse Source 
24MHz is the nominal external clock to use with OV7670.  (My testing
was actually at 16MHz)
This commit is contained in:
Jeff Epler 2021-04-20 10:22:21 -05:00
parent 99799cded6
commit 5c5736ee1e
1 changed files with 4 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
ports/atmel-samd/common-hal/pwmio/PWMOut.c
View File

@ -156,7 +156,8 @@ pwmout_result_t common_hal_pwmio_pwmout_construct(pwmio_pwmout_obj_t* self,
return PWMOUT_INVALID_PIN; return PWMOUT_INVALID_PIN;
} }
if (frequency == 0 || frequency > 6000000) { uint32_t system_clock = common_hal_mcu_processor_get_frequency();
if (frequency == 0 || frequency > system_clock/2) {
return PWMOUT_INVALID_FREQUENCY; return PWMOUT_INVALID_FREQUENCY;
} }
@ -237,7 +238,6 @@ pwmout_result_t common_hal_pwmio_pwmout_construct(pwmio_pwmout_obj_t* self,
resolution = tcc_sizes[timer->index]; resolution = tcc_sizes[timer->index];
} }
// First determine the divisor that gets us the highest resolution. // First determine the divisor that gets us the highest resolution.
uint32_t system_clock = common_hal_mcu_processor_get_frequency();
uint32_t top; uint32_t top;
uint8_t divisor; uint8_t divisor;
for (divisor = 0; divisor < 8; divisor++) { for (divisor = 0; divisor < 8; divisor++) {
@ -413,7 +413,8 @@ uint16_t common_hal_pwmio_pwmout_get_duty_cycle(pwmio_pwmout_obj_t* self) {
void common_hal_pwmio_pwmout_set_frequency(pwmio_pwmout_obj_t* self, void common_hal_pwmio_pwmout_set_frequency(pwmio_pwmout_obj_t* self,
uint32_t frequency) { uint32_t frequency) {
if (frequency == 0 || frequency > 6000000) { uint32_t system_clock = common_hal_mcu_processor_get_frequency();
if (frequency == 0 || frequency > system_clock/2) {
mp_raise_ValueError(translate("Invalid PWM frequency")); mp_raise_ValueError(translate("Invalid PWM frequency"));
} }
const pin_timer_t* t = self->timer; const pin_timer_t* t = self->timer;
@ -424,7 +425,6 @@ void common_hal_pwmio_pwmout_set_frequency(pwmio_pwmout_obj_t* self,
// TCC resolution varies so look it up. // TCC resolution varies so look it up.
resolution = tcc_sizes[t->index]; resolution = tcc_sizes[t->index];
} }
uint32_t system_clock = common_hal_mcu_processor_get_frequency();
uint32_t new_top; uint32_t new_top;
uint8_t new_divisor; uint8_t new_divisor;
for (new_divisor = 0; new_divisor < 8; new_divisor++) { for (new_divisor = 0; new_divisor < 8; new_divisor++) {