什么是串口编程中的回调函数?它是如何工作的? [英] What is actually callback function in serial port programming?How it works?
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问题描述
function DUT_callback(obj, event, DUT_port)
persistent stored_data;
if isempty(stored_data)
stored_data = [];
end
if ~strcmp(DUT_port.status,'open')
return;
end
if ~DUT_port.BytesAvailable
return;
end
try
new_data = fread(DUT_port,DUT_port.BytesAvailable);
catch exception
fprintf('ERROR: Failed to read from DUT port. Shutting down.\n');
cleanup();
return;
end
data_array = [stored_data;new_data];
packet.NewPacket = 1;
while packet.NewPacket == 1
[packet,data_array] = parse_serial_data(data_array);
% Report bad checksum if appropriate
if packet.BadChecksum
end
% If packet was received, do stuff with it
if packet.NewPacket == 1
% HANDLE RAW GYRO DATA PACKET
if packet.Address == 86
% Extract the gyro data
gyro_x = typecast( flipud(uint8(packet.data(1:2))), 'int16' );
gyro_y = typecast( flipud(uint8(packet.data(3:4))), 'int16' );
gyro_z = typecast( flipud(uint8(packet.data(5:6))), 'int16' );
got_gyro_data = 1;
% fprintf('%d\t%d\t%d\n',gyro_x,gyro_y,gyro_z);
end
% HANDLE TEMPERATURE DATA PACKET
if packet.Address == 118
temperature = typecast( flipud(uint8(packet.data(1:4))), 'single' );
got_temperature_data = 1;
% fprintf('%3.2f\n',temperature);
end
% If we received gyro and temperature data, log it to
% the workspace if logging is enabled.
if got_temperature_data && got_gyro_data
got_temperature_data = 0;
got_gyro_data = 0;
if GDATA.logging_data == 1 && GDATA.selected_DUT > 0
if GDATA.DUT_samples_collected < GDATA.MAX_SAMPLES
GDATA.DUT_samples_collected = GDATA.DUT_samples_collected + 1;
GDATA.DUT_data(GDATA.DUT_samples_collected,:) = [single([GDATA.selected_DUT,gyro_x,gyro_y,gyro_z]),temperature];
else
fprintf('Maximum datapoints were collected. Logging disabled.\n');
GDATA.logging_data = 0;
end end end end end
推荐答案
回调是用户提供的功能,但是他/她没有明确地调用。相反,只要有事情发生就会被调用。例如,在串口通信中,可以调用它来处理串行事件(例如数据到达)。
A callback is a function the user provides but he/she doesn't explicitely call. Instead it is called whenever something happens. For instance, in serial port communication, it could be called in order to handle a serial event (e.g. data arrival).
这是本手册中最为出色的解释。
http:// www。 mathworks.com.au/help/matlab/matlab_external/events-and-callbacks.html [ ^ ]
http://www.mathworks.com.au/help/matlab/serial-port-devices.html [ ^ ]
This is all most excellently explained in the manual.
http://www.mathworks.com.au/help/matlab/matlab_external/events-and-callbacks.html[^]
http://www.mathworks.com.au/help/matlab/serial-port-devices.html[^]
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