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/*
* @file drv_pwm_servo.c
*
* Servo driver supporting PWM servos connected to kinetis flex timer modules.
*
*/
#include <nuttx/config.h>
#include <stdio.h>
#include <errno.h>
#include <chip.h>
#include <kinetis_ftm.h>
#include <kinetis_internal.h>
#include <up_arch.h>
#include <kinetis_sim.h>
#include "drv_pwm_servo.h"
/**
* Intialise the PWM servo outputs using the specified configuration.
*
* @param channel_mask Bitmask of channels (LSB = channel 0) to enable.
* This allows some of the channels to remain configured
* as GPIOs or as another function.
* @return OK on success.
*/
int
up_pwm_servo_init(uint32_t channel_mask)
{
for (size_t i = 0; i < PWM_SERVO_MAX_TIMERS; ++i) {
const struct pwm_servo_timer* timer = &pwm_servo_timers[i];
uint32_t regval;
regval = getreg32(timer->scgc);
putreg32(regval | timer->scgc_enable, timer->scgc); // enable clock signal
up_pwm_servo_set_rate_group_update(i, 50); // 50Hz default
}
for (size_t i = 0; i < PWM_SERVO_MAX_CHANNELS; ++i) {
const struct pwm_servo_channel* channel = &pwm_servo_channels[i];
if ((1 << i) & channel_mask) {
// enable edge aligned pwm
putreg32(0x28, channel->timer->ftm_base + KINETIS_FTM_CSC_OFFSET(channel->ftm_channel));
// configure pin
kinetis_pinconfig(channel->pinconfig);
}
}
return 0;
}
/**
* De-initialise the PWM servo outputs.
*/
void
up_pwm_servo_deinit(void)
{
}
/**
* Arm or disarm servo outputs.
*
* When disarmed, servos output no pulse.
*
* @bug This function should, but does not, guarantee that any pulse
* currently in progress is cleanly completed.
*
* @param armed If true, outputs are armed; if false they
* are disarmed.
*/
void up_pwm_servo_arm(bool armed)
{
for (size_t i = 0; i < PWM_SERVO_MAX_TIMERS; ++i) {
const struct pwm_servo_timer* timer = &pwm_servo_timers[i];
uint32_t regval = getreg32(timer->ftm_base + KINETIS_FTM_SC_OFFSET);
regval = regval & ~FTM_SC_CLKS_MASK;
if (armed) {
regval = regval | FTM_SC_CLKS_SYSCLK;
putreg32(regval, timer->ftm_base + KINETIS_FTM_SC_OFFSET);
} else {
regval = regval | FTM_SC_CLKS_NONE;
putreg32(regval, timer->ftm_base + KINETIS_FTM_SC_OFFSET);
}
}
}
/**
* Set the servo update rate for all rate groups.
*
* @param rate The update rate in Hz to set.
* @return OK on success, -ERANGE if an unsupported update rate is set.
*/
int
up_pwm_servo_set_rate(unsigned rate)
{
for (size_t i = 0; i < PWM_SERVO_MAX_TIMERS; ++i) {
up_pwm_servo_set_rate_group_update(i, rate);
}
return 0;
}
/**
* Get a bitmap of output channels assigned to a given rate group.
*
* @param group The rate group to query. Rate groups are assigned contiguously
* starting from zero.
* @return A bitmap of channels assigned to the rate group, or zero if
* the group number has no channels.
*/
uint32_t
up_pwm_servo_get_rate_group(unsigned group)
{
return 0;
}
/**
* Set the update rate for a given rate group.
*
* @param group The rate group whose update rate will be changed.
* @param rate The update rate in Hz.
* @return OK if the group was adjusted, -ERANGE if an unsupported update rate is set.
*/
int
up_pwm_servo_set_rate_group_update(unsigned group, unsigned rate)
{
if (group > PWM_SERVO_MAX_TIMERS) {
return -ERANGE;
}
/*
* ftm rate = bus frequency / prescaler
* rate = ftm rate / modulo
*
* - bus 48MHz
* - prescaler 32
* - modulo 16-bit
* => minimum rate = 48E6/32/0xffff = 22.8 Hz
* => maximum rate = 48E6/32/1 => 1500000 Hz
* (arbitrarily limit to allow several duty cycle levels)
*/
if (rate < 23 || 10000 < rate) {
return -ERANGE;
}
const struct pwm_servo_timer* timer = &pwm_servo_timers[group];
uint32_t regval = getreg32(timer->ftm_base + KINETIS_FTM_SC_OFFSET);
regval = regval & ~FTM_SC_PS_MASK;
regval = regval | FTM_SC_PS_32;
putreg32(regval, timer->ftm_base + KINETIS_FTM_SC_OFFSET);
putreg32(0, timer->ftm_base + KINETIS_FTM_CNT_OFFSET);
putreg32(0, timer->ftm_base + KINETIS_FTM_CNTIN_OFFSET);
putreg32(
BOARD_BUS_FREQ / 32 / rate,
timer->ftm_base + KINETIS_FTM_MOD_OFFSET);
return 0;
}
/**
* Set the current output value for a channel.
*
* @param channel The channel to set.
* @param value The output pulse width in microseconds.
*/
int
up_pwm_servo_set(unsigned channel, servo_position_t value)
{
if (channel > PWM_SERVO_MAX_CHANNELS) {
return -ERANGE;
}
const struct pwm_servo_channel* ch = &pwm_servo_channels[channel];
putreg32(
BOARD_BUS_FREQ / 1000000 * ((uint32_t) value) / 32,
ch->timer->ftm_base + KINETIS_FTM_CV_OFFSET(ch->ftm_channel));
return 0;
}
/**
* Get the current output value for a channel.
*
* @param channel The channel to read.
* @return The output pulse width in microseconds, or zero if
* outputs are not armed or not configured.
*/
servo_position_t
up_pwm_servo_get(unsigned channel)
{
if (channel > PWM_SERVO_MAX_CHANNELS) {
return -ERANGE;
}
const struct pwm_servo_channel* ch = &pwm_servo_channels[channel];
uint32_t reg = ch->timer->ftm_base + KINETIS_FTM_CV_OFFSET(ch->ftm_channel);
uint32_t mod = getreg32(reg);
return mod * 32 / (BOARD_BUS_FREQ/1000000);
}
