function [value,status] = cm_read_register(handle,address);
%Camera module register read.
%   [VALUE,STATUS] = CM_READ_REGISTER(HANDLE,ADDRESS);
%
%   Input Parameters:
%   ================
%
%      handle ------------> Handle to camera module object (positive integer).
%      address -----------> Register address hexadecimal (4 character string).
%
%   Output Parameters:
%   =================
%
%      value -------------> Register value hexadecimal (4 character string).
%      status ------------> Success status (-1 = error, +1 = success).
%
%   See also CM_WRITE_REGISTER.

% Stephan Hengstler
% Stanford Wireless Sensor Networks Lab
% December 27, 2004
%
% Last modified: 02-09-2005

%*********************** Camera Module Read Register **************************************

% initalize output parameters
value			= '0000';

% flush serial receive buffer
packet		= com_recv(handle,5);

% read register until timeout
timeout		= 0;
while(timeout < 100)
   
	% create command packet
	packet 		= ['01';address(1:2);address(3:4);'02'];
	packet		= char(hex2dec(packet)');

	% send command packet
	status		= com_send(handle,packet);
	pause(0.001)

	% receive response packet
	packet 		= [];
	packet		= com_recv(handle,5);

	% valid response packet?
	if (length(packet) == 5)
	   break;
   end
   
   % increment timeout counter
	timeout		= timeout + 1;

end

% check for error
if (length(packet) < 5)
   status		= -1;
   return;
end

% extract register value
value			= dec2hex(256*bitand(double(packet(2)),255)+bitand(double(packet(3)),255),4);

% return status
status		= 1;