mirror of
https://github.com/ArduPilot/ardupilot
synced 2025-01-03 22:48:29 -04:00
6e9756ff79
Now instead of requiring the buffer to fill completely before we can detect it is not draining, we use a time based mechanism to detect when none of the first few bytes are transmitted after sitting in our buffer a half second or more after flow control is enabled. This huristic is reliable only for the first several chracters because we believe that the radio must still have plenty of room in it's own buffers at that time even if it is not able to transmit them to the other radio yet. Note that the original algorithm made the same assumption. The new algorithm is especially helpful for cases where only keepalive messages are transmitted before other packets can be requested by the GCS. In this situation, the original code required almost 2 minutes to disable flow control and allow communication with the GCS.
85 lines
2.1 KiB
C++
85 lines
2.1 KiB
C++
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#ifndef __AP_HAL_PX4_UARTDRIVER_H__
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#define __AP_HAL_PX4_UARTDRIVER_H__
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#include "AP_HAL_PX4.h"
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#include <systemlib/perf_counter.h>
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class PX4::PX4UARTDriver : public AP_HAL::UARTDriver {
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public:
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PX4UARTDriver(const char *devpath, const char *perf_name);
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/* PX4 implementations of UARTDriver virtual methods */
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void begin(uint32_t b);
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void begin(uint32_t b, uint16_t rxS, uint16_t txS);
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void end();
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void flush();
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bool is_initialized();
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void set_blocking_writes(bool blocking);
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bool tx_pending();
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/* PX4 implementations of Stream virtual methods */
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int16_t available();
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int16_t txspace();
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int16_t read();
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/* PX4 implementations of Print virtual methods */
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size_t write(uint8_t c);
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size_t write(const uint8_t *buffer, size_t size);
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void set_device_path(const char *path) {
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_devpath = path;
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}
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void _timer_tick(void);
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int _get_fd(void) {
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return _fd;
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}
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void set_flow_control(enum flow_control flow_control);
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enum flow_control get_flow_control(void) { return _flow_control; }
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private:
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const char *_devpath;
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int _fd;
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uint32_t _baudrate;
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volatile bool _initialised;
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volatile bool _in_timer;
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bool _nonblocking_writes;
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// we use in-task ring buffers to reduce the system call cost
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// of ::read() and ::write() in the main loop
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uint8_t *_readbuf;
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uint16_t _readbuf_size;
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// _head is where the next available data is. _tail is where new
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// data is put
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volatile uint16_t _readbuf_head;
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volatile uint16_t _readbuf_tail;
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uint8_t *_writebuf;
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uint16_t _writebuf_size;
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volatile uint16_t _writebuf_head;
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volatile uint16_t _writebuf_tail;
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perf_counter_t _perf_uart;
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int _write_fd(const uint8_t *buf, uint16_t n);
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int _read_fd(uint8_t *buf, uint16_t n);
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uint64_t _first_write_time;
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uint64_t _last_write_time;
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void try_initialise(void);
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uint32_t _last_initialise_attempt_ms;
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uint32_t _os_start_auto_space;
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uint32_t _total_read;
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uint32_t _total_written;
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enum flow_control _flow_control;
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pid_t _uart_owner_pid;
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};
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#endif // __AP_HAL_PX4_UARTDRIVER_H__
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