ardupilot/libraries/AP_HAL_ChibiOS/RCOutput.h

/*
 * This file 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 file 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/>.
 * 
 * Code by Andrew Tridgell and Siddharth Bharat Purohit
 */
#pragma once

#include "AP_HAL_ChibiOS.h"
#include "shared_dma.h"
#include "ch.h"
#include "hal.h"

#if HAL_USE_PWM == TRUE

class ChibiOS::RCOutput : public AP_HAL::RCOutput {
public:
    void     init();
    void     set_freq(uint32_t chmask, uint16_t freq_hz);
    uint16_t get_freq(uint8_t ch);
    void     enable_ch(uint8_t ch);
    void     disable_ch(uint8_t ch);
    void     write(uint8_t ch, uint16_t period_us);
    uint16_t read(uint8_t ch);
    void     read(uint16_t* period_us, uint8_t len);
    uint16_t read_last_sent(uint8_t ch) override;
    void     read_last_sent(uint16_t* period_us, uint8_t len) override;
    void     set_esc_scaling(uint16_t min_pwm, uint16_t max_pwm) override {
        _esc_pwm_min = min_pwm;
        _esc_pwm_max = max_pwm;
    }
    bool     get_esc_scaling(uint16_t &min_pwm, uint16_t &max_pwm) override {
        min_pwm = _esc_pwm_min;
        max_pwm = _esc_pwm_max;
        return true;
    }
    void set_output_mode(uint16_t mask, enum output_mode mode) override;

    float scale_esc_to_unity(uint16_t pwm) override {
        return 2.0 * ((float) pwm - _esc_pwm_min) / (_esc_pwm_max - _esc_pwm_min) - 1.0;
    }
    
    void     cork(void) override;
    void     push(void) override;

    /*
      force the safety switch on, disabling PWM output from the IO board
     */
    bool force_safety_on(void) override;

    /*
      force the safety switch off, enabling PWM output from the IO board
     */
    void force_safety_off(void) override;

    bool enable_px4io_sbus_out(uint16_t rate_hz) override;

    /*
      set default update rate
     */
    void set_default_rate(uint16_t rate_hz) override;

    /*
      timer push (for oneshot min rate)
     */
    void timer_tick(void) override;

    /*
      setup for serial output to a set of ESCs, using the given
      baudrate. Assumes 1 start bit, 1 stop bit, LSB first and 8
      databits. This is used for ESC configuration and firmware
      flashing
     */
    bool setup_serial_output(uint16_t chan_mask, ByteBuffer *buffer, uint32_t baudrate);

    /*
      setup for serial output to an ESC using the given
      baudrate. Assumes 1 start bit, 1 stop bit, LSB first and 8
      databits. This is used for passthrough ESC configuration and
      firmware flashing

      While serial output is active normal output to this channel is
      suspended. Output to some other channels (such as those in the
      same channel timer group) may also be stopped, depending on the
      implementation
     */
    bool serial_setup_output(uint8_t chan, uint32_t baudrate) override;

    /*
      write a set of bytes to an ESC, using settings from
      serial_setup_output. This is a blocking call
     */
    bool serial_write_bytes(const uint8_t *bytes, uint16_t len) override;

    /*
      read a byte from a port, using serial parameters from serial_setup_output()
      return the number of bytes read
     */
    uint16_t serial_read_bytes(uint8_t *buf, uint16_t len) override;
    
    /*
      stop serial output. This restores the previous output mode for
      the channel and any other channels that were stopped by
      serial_setup_output()
     */
    void serial_end(void) override;

    /*
      enable telemetry request for a mask of channels. This is used
      with DShot to get telemetry feedback
     */
    void set_telem_request_mask(uint16_t mask) { telem_request_mask = (mask >> chan_offset); }
    
private:
    struct pwm_group {
        // only advanced timers can do high clocks needed for more than 400Hz
        bool advanced_timer;
        uint8_t chan[4]; // chan number, zero based, 255 for disabled
        PWMConfig pwm_cfg;
        PWMDriver* pwm_drv;
        bool have_up_dma; // can we do DMAR outputs for DShot?
        uint8_t dma_up_stream_id;
        uint8_t dma_up_channel;
        uint8_t alt_functions[4];
        ioline_t pal_lines[4];

        // below this line is not initialised by hwdef.h
        enum output_mode current_mode;
        uint16_t frequency_hz;
        uint16_t ch_mask;
        const stm32_dma_stream_t *dma;
        Shared_DMA *dma_handle;
        uint32_t *dma_buffer;
        bool have_lock;
        bool pwm_started;
        uint32_t bit_width_mul;
        uint32_t rc_frequency;
        bool in_serial_dma;
        uint64_t last_dshot_send_us;

        // serial output
        struct {
            // expected time per bit
            uint32_t bit_time_us;
            
            // channel to output to within group (0 to 3)
            uint8_t chan;

            // thread waiting for byte to be written
            thread_t *waiter;        
        } serial;
    };

    /*
      structure for IRQ handler for soft-serial input
     */
    static struct irq_state {
        // ioline for port being read
        ioline_t line;

        // time the current byte started
        uint32_t byte_start_us;

        // number of bits we have read in this byte
        uint8_t nbits;

        // bitmask of bits so far (includes start and stop bits)
        uint16_t bitmask;

        // value of completed byte (includes start and stop bits)        
        uint16_t byteval;

        // expected time per bit
        uint32_t bit_time_us;

        // the bit value of the last bit received
        uint8_t last_bit;
        
        // thread waiting for byte to be read
        thread_t *waiter;
    } irq;

    
    // the group being used for serial output
    struct pwm_group *serial_group;
    thread_t *serial_thread;
    tprio_t serial_priority;

    static pwm_group pwm_group_list[];
    uint16_t _esc_pwm_min;
    uint16_t _esc_pwm_max;

    // offset of first local channel
    uint8_t chan_offset;

    // total number of channels
    uint8_t total_channels;
    
    // last sent values are for all channels
    uint16_t last_sent[16];
    
    // these values are for the local channels. Non-local channels are handled by IOMCU
    uint32_t en_mask;
    uint16_t period[16];
    uint8_t num_channels;
    bool corked;
    // mask of channels that are running in high speed
    uint16_t fast_channel_mask;

    // min time to trigger next pulse to prevent overlap
    uint64_t min_pulse_trigger_us;

    // mutex for oneshot triggering
    mutex_t trigger_mutex;

    // which output groups need triggering
    uint8_t trigger_groupmask;

    // widest pulse for oneshot triggering
    uint16_t trigger_widest_pulse;

    // are we using oneshot125 for the iomcu?
    bool iomcu_oneshot125;

    // push out values to local PWM
    void push_local(void);

    // trigger group pulses
    void trigger_groups(void);

    // setup output frequency for a group
    void set_freq_group(pwm_group &group);
    
    /*
      DShot handling
     */
    const uint8_t dshot_post = 6;
    const uint16_t dshot_bit_length = 16 + dshot_post;
    const uint16_t dshot_buffer_length = dshot_bit_length*4*sizeof(uint32_t);
    uint32_t dshot_pulse_time_us;
    uint16_t telem_request_mask;
    
    void dma_allocate(Shared_DMA *ctx);
    void dma_deallocate(Shared_DMA *ctx);    
    uint16_t create_dshot_packet(const uint16_t value, bool telem_request);
    void fill_DMA_buffer_dshot(uint32_t *buffer, uint8_t stride, uint16_t packet, uint16_t clockmul);
    void dshot_send(pwm_group &group, bool blocking);
    static void dma_irq_callback(void *p, uint32_t flags);
    bool mode_requires_dma(enum output_mode mode) const;
    bool setup_group_DMA(pwm_group &group, uint32_t bitrate, uint32_t bit_width, bool active_high);
    void send_pulses_DMAR(pwm_group &group, uint32_t buffer_length);
    void set_group_mode(pwm_group &group);

    // serial output support
    static const eventmask_t serial_event_mask = EVENT_MASK(1);
    bool serial_write_byte(uint8_t b);
    bool serial_read_byte(uint8_t &b);
    void fill_DMA_buffer_byte(uint32_t *buffer, uint8_t stride, uint8_t b , uint32_t bitval);
    static void serial_bit_irq(void);

};

#endif // HAL_USE_PWM