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HAL_Linux: implement uart timestamp API

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This commit is contained in:
Andrew Tridgell 2018-05-16 10:47:42 +10:00
parent f4f62ececa
commit b8eeac41c8
2 changed files with 50 additions and 0 deletions
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30
libraries/AP_HAL_Linux/UARTDriver.cpp
View File

@ -87,6 +87,8 @@ void UARTDriver::begin(uint32_t b, uint16_t rxS, uint16_t txS)
_device->set_speed(b);
_baudrate = b;
_allocate_buffers(rxS, txS);
}
@ -471,6 +473,10 @@ void UARTDriver::_timer_tick(void)
}
_readbuf.commit((unsigned)ret);
// update receive timestamp
_receive_timestamp[_receive_timestamp_idx^1] = AP_HAL::micros64();
_receive_timestamp_idx ^= 1;
/* stop reading as we read less than we asked for */
if ((unsigned)ret < vec[i].len) {
break;
@ -479,3 +485,27 @@ void UARTDriver::_timer_tick(void)
_in_timer = false;
}
/*
return timestamp estimate in microseconds for when the start of
a nbytes packet arrived on the uart. This should be treated as a
time constraint, not an exact time. It is guaranteed that the
packet did not start being received after this time, but it
could have been in a system buffer before the returned time.
This takes account of the baudrate of the link. For transports
that have no baudrate (such as USB) the time estimate may be
less accurate.
A return value of zero means the HAL does not support this API
*/
uint64_t UARTDriver::receive_time_constraint_us(uint16_t nbytes) const
{
uint64_t last_receive_us = _receive_timestamp[_receive_timestamp_idx];
if (_baudrate > 0) {
// assume 10 bits per byte.
uint32_t transport_time_us = (1000000UL * 10UL / _baudrate) * nbytes;
last_receive_us -= transport_time_us;
}
return last_receive_us;
}

20
libraries/AP_HAL_Linux/UARTDriver.h
View File

@ -49,12 +49,28 @@ public:
_device->set_flow_control(flow_control_setting);
}
/*
return timestamp estimate in microseconds for when the start of
a nbytes packet arrived on the uart. This should be treated as a
time constraint, not an exact time. It is guaranteed that the
packet did not start being received after this time, but it
could have been in a system buffer before the returned time.
This takes account of the baudrate of the link. For transports
that have no baudrate (such as USB) the time estimate may be
less accurate.
A return value of zero means the HAL does not support this API
*/
uint64_t receive_time_constraint_us(uint16_t nbytes) const override;
private:
AP_HAL::OwnPtr<SerialDevice> _device;
bool _nonblocking_writes;
bool _console;
volatile bool _in_timer;
uint16_t _base_port;
uint32_t _baudrate;
char *_ip;
char *_flag;
bool _connected; // true if a client has connected
@ -66,6 +82,10 @@ private:
AP_HAL::OwnPtr<SerialDevice> _parseDevicePath(const char *arg);
uint64_t _last_write_time;
// timestamp for receiving data on the UART, avoiding a lock
uint64_t _receive_timestamp[2];
uint8_t _receive_timestamp_idx;
protected:
const char *device_path;
volatile bool _initialised;