Marlin 2.0 for Flying Bear 4S/5
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/**
* Marlin 3D Printer Firmware
* Copyright (C) 2017 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
*
* Based on Sprinter and grbl.
* Copyright (C) 2011 Camiel Gubbels / Erik van der Zalm
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
/**
* The class Servo uses the PWM class to implement its functions
*
* All PWMs use the same repetition rate - 20mS because that's the normal servo rate
*/
/**
* This is a hybrid system.
*
* The PWM1 module is used to directly control the Servo 0, 1 & 3 pins. This keeps
* the pulse width jitter to under a microsecond.
*
* For all other pins the PWM1 module is used to generate interrupts. The ISR
* routine does the actual setting/clearing of pins. The upside is that any pin can
* have a PWM channel assigned to it. The downside is that there is more pulse width
* jitter. The jitter depends on what else is happening in the system and what ISRs
* prempt the PWM ISR. Writing to the SD card can add 20 microseconds to the pulse
* width.
*/
/**
* The data structures are setup to minimize the computation done by the ISR which
* minimizes ISR execution time. Execution times are 2.2 - 3.7 microseconds.
*
* Two tables are used. active_table is used by the ISR. Changes to the table are
* are done by copying the active_table into the work_table, updating the work_table
* and then swapping the two tables. Swapping is done by manipulating pointers.
*
* Immediately after the swap the ISR uses the work_table until the start of the
* next 20mS cycle. During this transition the "work_table" is actually the table
* that was being used before the swap. The "active_table" contains the data that
* will start being used at the start of the next 20mS period. This keeps the pins
* well behaved during the transition.
*
* The ISR's priority is set to the maximum otherwise other ISRs can cause considerable
* jitter in the PWM high time.
*
* See the end of this file for details on the hardware/firmware interaction
*/
#include "fastio.h"
#define LPC_PWM1_MR0 19999 // base repetition rate minus one count - 20mS
#define LPC_PWM1_PR 24 // prescaler value - prescaler divide by 24 + 1 - 1 MHz output
#define LPC_PWM1_PCLKSEL0 0x00 // select clock source for prescaler - defaults to 25MHz on power up
// 0: 25MHz, 1: 100MHz, 2: 50MHz, 3: 12.5MHZ to PWM1 prescaler
#define MR0_MARGIN 200 // if channel value too close to MR0 the system locks up
void LPC1768_PWM_init(void);
bool LPC1768_PWM_attach_pin(pin_t pin, uint32_t min = 1, uint32_t max = (LPC_PWM1_MR0 - MR0_MARGIN), uint8_t servo_index = 0xff);
void LPC1768_PWM_update_map_MR(void);
void LPC1768_PWM_update(void);
bool LPC1768_PWM_write(pin_t pin, uint32_t value);
bool LPC1768_PWM_detach_pin(pin_t pin);
bool useable_hardware_PWM(pin_t pin);