Manual

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Figure 3-2 RPLIDAR Functions related to Measurement Scan Operation

The startScan() function will start a background worker thread to receive the

measurement scan data sequence sent from RPLIDAR asynchronously. The

received data sequence is stored in the driver’s internal cache for the

grabScanData() function to fetch.

User programs can use the grabScanData() function to retrieve the scan data

sequence previously received and cached by the driver. This function always

returns a latest and complete 360-degrees’ measurement scan data sequence.

After each grabScanData() call, the internal data cache will be cleared to ensure

the grabScanData() won’t get duplicated data.

In case a complete 360-degrees’ scan sequence hasn’t been available at the

time when grabScanData() is called, the function will wait until a complete scan

data is received by the driver or the given timeout duration is expired. User

programs can tune this timeout value to meet different application requirements.

Note: the startScan() and stop() functions don’t control the scanning motor

of the RPLIDAR directly. The host system should control the scanning motor to

rotate or stop via the PWM pin.

Function Name

Brief description

startScan()

Request the RPLIDAR core to start measurement scan operation

and send out result data continuously

If the Express Scan mode is supported, and the program invokes

the startScan() by using the default parameters

startScanNormal()

Force the RPLIDAR core to start measurement scan operation in

Scan mode

startScanExpress()

Force the RPLIDAR core to start measurement scan operation in

Express Scan mode. It the RPLIDAR firmware not supports Express

Scan mode, the function will fail the execution.

stop()

Request the RPLIDAR core to stop the me as asurement scan

operation.

grabScanData()

Grab a complete 360-degrees’ scan data sequence.

ascendScanData()

Rank the scan data from grabScanData() as the angle inscreases.