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pwm.pio
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pwm.pio
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.program pwm
.wrap_target
mov x, !NULL ; x = 0xffffffff
loop_high: ; do {
jmp x-- cont_loop_high ; x--
cont_loop_high: ;
nop ; nop to match number of cycles below
jmp pin loop_high ; } while pin is high
in x, 16 ; Copy 16 bits of counter into ISR
loop_low: ; do {
jmp x-- cont_loop_low ; x--
cont_loop_low: ;
jmp pin exit_loop_low ; if pin is high: break
jmp loop_low ; } while 1
exit_loop_low:
in x, 16 ; Copy 16 bits of counter into ISR
.wrap
% c-sdk {
#include "hardware/gpio.h"
#include "hardware/pio.h"
static inline void pwm_program_init(
PIO pio,
uint sm,
uint offset,
uint pin
) {
// Set the pin direction to input at the PIO
pio_sm_set_consecutive_pindirs(pio, sm, pin, 1, false);
pio_gpio_init(pio, pin);
gpio_pull_up(pin);
// Map the pin as both input and jump pin.
pio_sm_config c = pwm_program_get_default_config(offset);
sm_config_set_in_pins(&c, pin);
sm_config_set_jmp_pin(&c, pin);
sm_config_set_in_shift(&c, false, true, 32);
// Load our configuration, and jump to the start of the program
pio_sm_init(pio, sm, offset, &c);
// Set the state machine running
pio_sm_set_enabled(pio, sm, true);
}
%}