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HAL_SITL: implement UART timestamp API

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This commit is contained in:
Andrew Tridgell 2018-05-16 10:52:08 +10:00
parent b8eeac41c8
commit 4e452c77f8
2 changed files with 44 additions and 1 deletions
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28
libraries/AP_HAL_SITL/UARTDriver.cpp
View File

@ -52,6 +52,9 @@ void UARTDriver::begin(uint32_t baud, uint16_t rxSpace, uint16_t txSpace)
{
const char *path = _sitlState->_uart_path[_portNumber];
// default to 1MBit
_uart_baudrate = 1000000U;
if (strcmp(path, "GPS1") == 0) {
/* gps */
_connected = true;
@ -498,8 +501,33 @@ void UARTDriver::_timer_tick(void)
}
if (nread > 0) {
_readbuffer.write((uint8_t *)buf, nread);
_receive_timestamp = AP_HAL::micros64();
}
}
/*
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;
if (_uart_baudrate > 0) {
// assume 10 bits per byte.
uint32_t transport_time_us = (1000000UL * 10UL / _uart_baudrate) * nbytes;
last_receive_us -= transport_time_us;
}
return last_receive_us;
}
#endif // CONFIG_HAL_BOARD

17
libraries/AP_HAL_SITL/UARTDriver.h
View File

@ -66,6 +66,21 @@ public:
bool set_unbuffered_writes(bool on) override;
void _timer_tick(void);
/*
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:
uint8_t _portNumber;
@ -94,7 +109,7 @@ private:
bool set_speed(int speed);
SITL_State *_sitlState;
uint64_t _receive_timestamp;
};
#endif