/**
* @file pwmout.c
*
* @ingroup lpc176x
*
* @brief PWM-Out controller for the mbed lpc1768 board.
*/
/*
* Copyright (c) 2014 Taller Technologies.
*
* @author Diaz Marcos (marcos.diaz@tallertechnologies.com)
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
#include <rtems/status-checks.h>
#include <bsp/pwmout.h>
#include <bsp/pwmout-defs.h>
/**
* @brief The low level device.
*/
static lpc176x_pwm_device *const pwm_device =
(lpc176x_pwm_device *) PWM1_BASE_ADDR;
/**
* @brief The possible output pins for each PWM output.
*/
static const lpc176x_pwm_pin pwm_pins[ PWM_OUTPUT_NUMBER ][ PWM_NUMBER_OF_PINS
] =
{
{ { 50u, LPC176X_PIN_FUNCTION_10 }, { 64u, LPC176X_PIN_FUNCTION_01 } },
{ { 52u, LPC176X_PIN_FUNCTION_10 }, { 65u, LPC176X_PIN_FUNCTION_01 } },
{ { 53u, LPC176X_PIN_FUNCTION_10 }, { 66u, LPC176X_PIN_FUNCTION_01 } },
{ { 55u, LPC176X_PIN_FUNCTION_10 }, { 67u, LPC176X_PIN_FUNCTION_01 } },
{ { 56u, LPC176X_PIN_FUNCTION_10 }, { 68u, LPC176X_PIN_FUNCTION_01 } },
{ { 58u, LPC176X_PIN_FUNCTION_10 }, { 69u, LPC176X_PIN_FUNCTION_01 } },
};
/**
* @brief The pointers to the low level match registers for each PWM output.
*/
static volatile uint32_t *const pwm_match[ PWM_OUTPUT_NUMBER ] = {
&PWM1MR1,
&PWM1MR2,
&PWM1MR3,
&PWM1MR4,
&PWM1MR5,
&PWM1MR6
};
/**
* @brief Checks if a pin number is valid for the given PWM,
* and sets the corresponding pin function for that pin.
*
* @param pin_number The pin number to search.
* @param pwm In which PWM search for the pin number.
* @param pin_function If the pin number is found, here we return
* the pin function for that pin number.
* @return True if found, false otherwise.
*/
static inline bool is_found_in_this_pwm(
const lpc176x_pin_number pin_number,
const lpc176x_pwm_number pwm,
lpc176x_pin_function *const pin_function
)
{
lpc176x_pwm_pin_number pnumber = PWM_FIRST_PIN;
bool found = false;
while (!found && ( pnumber < PWM_NUMBER_OF_PINS ))
{
if ( pwm_pins[ pwm ][ pnumber ].pin_number == pin_number ) {
found = true;
*pin_function = pwm_pins[ pwm ][ pnumber ].pin_function;
}/*else implies that the pin number was not found. Keep looking.*/
++pnumber;
}
return found;
}
/**
* @brief Checks if a pin number is valid for any PWM,
* and sets the corresponding pin function for that pin.
*
* @param pin_number The pin number to search.
* @param pwm If is found here we return in which PWM was found.
* @param pin_function If the pin number is found the pin function
* for this pin number one will be returned.
* @return True if found, false otherwise.
*/
static bool is_valid_pin_number(
const lpc176x_pin_number pin_number,
lpc176x_pwm_number *const pwm,
lpc176x_pin_function *const pin_function
)
{
bool found = false;
lpc176x_pwm_number pwm_local = PWMO_1;
while(!found && ( pwm_local < PWM_OUTPUT_NUMBER ))
{
if ( is_found_in_this_pwm( pin_number, pwm_local, pin_function ) ) {
*pwm = pwm_local;
found = true;
} /*else implies that the pin number was not found. Keep looking.*/
++pwm_local;
}
return found;
}
/**
* @brief Sets the period for the given PWM.
*
* @param pwm The PWM output in which the period will be set.
* @param period The period to set.
*/
static void set_period(
const lpc176x_pwm_number pwm,
const lpc176x_microseconds period
)
{
pwm_device->TCR = PWM_TCR_RESET;
pwm_device->MR0 = period * PWM_PRESCALER_USECOND;
pwm_device->LER |= PWM_LER_LATCH_MATCH_0;
pwm_device->TCR = PWM_TCR_PWM | PWM_TCR_ENABLE;
}
/**
* @brief Sets the pulsewidth for the given PWM.
*
* @param pwm The PWM output in which the pulsewidth will be set.
* @param pwidth The pulse width to set.
*/
static void set_pulsewidth(
const lpc176x_pwm_number pwm,
lpc176x_microseconds pwidth
)
{
pwidth *= PWM_PRESCALER_USECOND;
if ( pwm_device->MR0 == pwidth ) {
++pwidth;
} /* Not the same as the period, do nothing.*/
*( pwm_match[ pwm ] ) = pwidth;
pwm_device->LER |= PWM_LER_LATCH( pwm );
}
rtems_status_code pwm_init( const lpc176x_pin_number pin_number )
{
rtems_status_code sc = RTEMS_INVALID_NUMBER;
lpc176x_pin_function pin_function;
lpc176x_pwm_number pwm;
if ( is_valid_pin_number( pin_number, &pwm, &pin_function ) ) {
sc = lpc176x_module_enable( LPC176X_MODULE_PWM_1,
LPC176X_MODULE_PCLK_DEFAULT );
RTEMS_CHECK_SC( sc, "enable pwm module" );
pwm_device->PR = 0;
pwm_device->MCR = PWM_MCR_RESET_ON_MATCH0;
pwm_device->PCR |= PWM_PCR_ENABLE_PWM( pwm );
set_period( pwm, PWM_DEFAULT_PERIOD );
set_pulsewidth( pwm, PWM_DEFAULT_PULSEWIDTH );
lpc176x_pin_select( pin_number, pin_function );
} /* else implies that the pin number is not valid.
So, a RTEMS_INVALID_NUMBER will be returned.*/
return sc;
}
rtems_status_code pwm_period(
const lpc176x_pin_number pin_number,
const lpc176x_microseconds period
)
{
rtems_status_code sc = RTEMS_INVALID_NUMBER;
lpc176x_pin_function pin_function;
lpc176x_pwm_number pwm;
if ( is_valid_pin_number( pin_number, &pwm, &pin_function ) ) {
sc = RTEMS_SUCCESSFUL;
set_period( pwm, period );
} /* else implies that the pin number is not valid.
So, a RTEMS_INVALID_NUMBER will be returned.*/
return sc;
}
rtems_status_code pwm_pulsewidth(
const lpc176x_pin_number pin_number,
const lpc176x_microseconds pwidth
)
{
rtems_status_code sc = RTEMS_INVALID_NUMBER;
lpc176x_pin_function pin_function;
lpc176x_pwm_number pwm;
if ( is_valid_pin_number( pin_number, &pwm, &pin_function ) ) {
sc = RTEMS_SUCCESSFUL;
set_pulsewidth( pwm, pwidth );
} /* Else wrong pin_number return RTEMS_INVALID_NUMBER*/
return sc;
}
