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micropython/teensy/servo.c

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#include <stdio.h>
#include "misc.h"
#include "mpconfig.h"
#include "qstr.h"
#include "nlr.h"
#include "obj.h"
#include "servo.h"
#include "Arduino.h"
#define MAX_SERVOS 12
#define INVALID_SERVO -1
#define MIN_PULSE_WIDTH 544 // the shortest pulse sent to a servo
#define MAX_PULSE_WIDTH 2400 // the longest pulse sent to a servo
#define DEFAULT_PULSE_WIDTH 1500 // default pulse width when servo is attached
#define REFRESH_INTERVAL 20000 // minumim time to refresh servos in microseconds
#define PDB_CONFIG (PDB_SC_TRGSEL(15) | PDB_SC_PDBEN | PDB_SC_PDBIE \
| PDB_SC_CONT | PDB_SC_PRESCALER(2) | PDB_SC_MULT(0))
#define PDB_PRESCALE 4
#define usToTicks(us) ((us) * (F_BUS / 1000) / PDB_PRESCALE / 1000)
#define ticksToUs(ticks) ((ticks) * PDB_PRESCALE * 1000 / (F_BUS / 1000))
static uint16_t servo_active_mask = 0;
static uint16_t servo_allocated_mask = 0;
static uint8_t servo_pin[MAX_SERVOS];
static uint16_t servo_ticks[MAX_SERVOS];
typedef struct _pyb_servo_obj_t {
mp_obj_base_t base;
uint servo_id;
uint min_usecs;
uint max_usecs;
} pyb_servo_obj_t;
#define clamp(v, min_val, max_val) ((v) < (min_val) ? (min_val) : (v) > (max_val) ? (max_val) : (v))
static float map_uint_to_float(uint x, uint in_min, uint in_max, float out_min, float out_max)
{
return (float)(x - in_min) * (out_max - out_min) / (float)(in_max - in_min) + (float)out_min;
}
static uint map_float_to_uint(float x, float in_min, float in_max, uint out_min, uint out_max)
{
return (int)((x - in_min) * (float)(out_max - out_min) / (in_max - in_min) + (float)out_min);
}
static mp_obj_t servo_obj_attach(mp_obj_t self_in, mp_obj_t pin_obj) {
pyb_servo_obj_t *self = self_in;
uint pin = mp_obj_get_int(pin_obj);
if (pin > CORE_NUM_DIGITAL) {
goto pin_error;
}
pinMode(pin, OUTPUT);
servo_pin[self->servo_id] = pin;
servo_active_mask |= (1 << self->servo_id);
if (!(SIM_SCGC6 & SIM_SCGC6_PDB)) {
SIM_SCGC6 |= SIM_SCGC6_PDB; // TODO: use bitband for atomic bitset
PDB0_MOD = 0xFFFF;
PDB0_CNT = 0;
PDB0_IDLY = 0;
PDB0_SC = PDB_CONFIG;
// TODO: maybe this should be a higher priority than most
// other interrupts (init all to some default?)
PDB0_SC = PDB_CONFIG | PDB_SC_SWTRIG;
}
NVIC_ENABLE_IRQ(IRQ_PDB);
return mp_const_none;
pin_error:
nlr_raise(mp_obj_new_exception_msg_varg(MP_QSTR_ValueError, "pin %d does not exist", pin));
}
static mp_obj_t servo_obj_detach(mp_obj_t self_in) {
//pyb_servo_obj_t *self = self_in;
return mp_const_none;
}
static mp_obj_t servo_obj_pin(mp_obj_t self_in) {
pyb_servo_obj_t *self = self_in;
return MP_OBJ_NEW_SMALL_INT(servo_pin[self->servo_id]);
}
static mp_obj_t servo_obj_min_usecs(int n_args, const mp_obj_t *args) {
pyb_servo_obj_t *self = args[0];
if (n_args == 1) {
// get min
return MP_OBJ_NEW_SMALL_INT(self->min_usecs);
}
// Set min
self->min_usecs = mp_obj_get_int(args[1]);
return mp_const_none;
}
static mp_obj_t servo_obj_max_usecs(int n_args, const mp_obj_t *args) {
pyb_servo_obj_t *self = args[0];
if (n_args == 1) {
// get max
return MP_OBJ_NEW_SMALL_INT(self->max_usecs);
}
// Set max
self->max_usecs = mp_obj_get_int(args[1]);
return mp_const_none;
}
static mp_obj_t servo_obj_angle(int n_args, const mp_obj_t *args) {
pyb_servo_obj_t *self = args[0];
if (n_args == 1) {
// get
float angle = map_uint_to_float(servo_ticks[self->servo_id],
usToTicks(self->min_usecs),
usToTicks(self->max_usecs),
0.0, 180.0);
return mp_obj_new_float(angle);
}
// Set
float angle = mp_obj_get_float(args[1]);
if (angle < 0.0F) {
angle = 0.0F;
}
if (angle > 180.0F) {
angle = 180.0F;
}
servo_ticks[self->servo_id] = map_float_to_uint(angle,
0.0F, 180.0F,
usToTicks(self->min_usecs),
usToTicks(self->max_usecs));
return mp_const_none;
}
static mp_obj_t servo_obj_usecs(int n_args, const mp_obj_t *args) {
pyb_servo_obj_t *self = args[0];
uint usecs;
if (n_args == 1) {
// get
return MP_OBJ_NEW_SMALL_INT(ticksToUs(servo_ticks[self->servo_id]));
}
// Set
usecs = mp_obj_get_int(args[1]);
if (self->min_usecs < self->max_usecs) {
usecs = clamp(usecs, self->min_usecs, self->max_usecs);
} else {
usecs = clamp(usecs, self->max_usecs, self->min_usecs);
}
servo_ticks[self->servo_id] = usToTicks(usecs);
return mp_const_none;
}
static mp_obj_t servo_obj_attached(mp_obj_t self_in) {
pyb_servo_obj_t *self = self_in;
uint attached = (servo_active_mask & (1 << self->servo_id)) != 0;
return MP_OBJ_NEW_SMALL_INT(attached);
}
static void servo_obj_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t self_in, mp_print_kind_t kind) {
pyb_servo_obj_t *self = self_in;
(void)kind;
print(env, "<Servo %lu>", self->servo_id);
}
static MP_DEFINE_CONST_FUN_OBJ_2(servo_obj_attach_obj, servo_obj_attach);
static MP_DEFINE_CONST_FUN_OBJ_1(servo_obj_detach_obj, servo_obj_detach);
static MP_DEFINE_CONST_FUN_OBJ_1(servo_obj_pin_obj, servo_obj_pin);
static MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(servo_obj_min_usecs_obj, 1, 2, servo_obj_min_usecs);
static MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(servo_obj_max_usecs_obj, 1, 2, servo_obj_max_usecs);
static MP_DEFINE_CONST_FUN_OBJ_1(servo_obj_attached_obj, servo_obj_attached);
static MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(servo_obj_angle_obj, 1, 2, servo_obj_angle);
static MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(servo_obj_usecs_obj, 1, 2, servo_obj_usecs);
static const mp_method_t servo_methods[] = {
{ "attach", &servo_obj_attach_obj },
{ "detach", &servo_obj_detach_obj },
{ "pin", &servo_obj_pin_obj },
{ "min_usecs", &servo_obj_min_usecs_obj },
{ "max_usecs", &servo_obj_max_usecs_obj },
{ "attached", &servo_obj_attached_obj },
{ "angle", &servo_obj_angle_obj },
{ "usecs", &servo_obj_usecs_obj },
{ NULL, NULL },
};
/*
* Notes:
*
* ISR needs to know pin #, ticks
*/
static const mp_obj_type_t servo_obj_type = {
{ &mp_type_type },
.name = MP_QSTR_Servo,
.print = servo_obj_print,
.methods = servo_methods,
};
/* servo = pyb.Servo(pin, [min_uecs, [max_usecs]]) */
mp_obj_t pyb_Servo(void) {
uint16_t mask;
pyb_servo_obj_t *self = m_new_obj(pyb_servo_obj_t);
self->base.type = &servo_obj_type;
self->min_usecs = MIN_PULSE_WIDTH;
self->max_usecs = MAX_PULSE_WIDTH;
/* Find an unallocated servo id */
self->servo_id = 0;
for (mask=1; mask < (1<<MAX_SERVOS); mask <<= 1) {
if (!(servo_allocated_mask & mask)) {
servo_allocated_mask |= mask;
servo_active_mask &= ~mask;
servo_ticks[self->servo_id] = usToTicks(DEFAULT_PULSE_WIDTH);
return self;
}
self->servo_id++;
}
m_del_obj(pyb_servo_obj_t, self);
nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "No available servo ids"));
return mp_const_none;
}
void pdb_isr(void)
{
static int8_t channel = 0, channel_high = MAX_SERVOS;
static uint32_t tick_accum = 0;
uint32_t ticks;
int32_t wait_ticks;
// first, if any channel was left high from the previous
// run, now is the time to shut it off
if (servo_active_mask & (1 << channel_high)) {
digitalWrite(servo_pin[channel_high], LOW);
channel_high = MAX_SERVOS;
}
// search for the next channel to turn on
while (channel < MAX_SERVOS) {
if (servo_active_mask & (1 << channel)) {
digitalWrite(servo_pin[channel], HIGH);
channel_high = channel;
ticks = servo_ticks[channel];
tick_accum += ticks;
PDB0_IDLY += ticks;
PDB0_SC = PDB_CONFIG | PDB_SC_LDOK;
channel++;
return;
}
channel++;
}
// when all channels have output, wait for the
// minimum refresh interval
wait_ticks = usToTicks(REFRESH_INTERVAL) - tick_accum;
if (wait_ticks < usToTicks(100)) wait_ticks = usToTicks(100);
else if (wait_ticks > 60000) wait_ticks = 60000;
tick_accum += wait_ticks;
PDB0_IDLY += wait_ticks;
PDB0_SC = PDB_CONFIG | PDB_SC_LDOK;
// if this wait is enough to satisfy the refresh
// interval, next time begin again at channel zero
if (tick_accum >= usToTicks(REFRESH_INTERVAL)) {
tick_accum = 0;
channel = 0;
}
}
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