1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 2<HTML> 3<HEAD> 4<META http-equiv="Content-Type" content="text/html; charset=windows-1252"> 5<META name="GENERATOR" content="IBM WebSphere Studio Homepage Builder Version 7.0.0.0 for Windows"> 6<META http-equiv="Content-Style-Type" content="text/css"> 7<TITLE>CAMERA_DmaRecv</TITLE> 8<LINK rel="stylesheet" href="../css/nitro.css" type="text/css"> 9</HEAD> 10<BODY> 11<H1 align="left">CAMERA_DmaRecv <IMG src="../image/TWL.gif" align="middle"></H1> 12<H2>Syntax</H2> 13<DL> 14 <DD> 15 <CODE>#include <twl/camera.h></CODE><BR> 16 <BR> 17 <CODE>void CAMERA_DmaRecv(u32 dmaNo, void *dest, u32 unit, u32 length);</CODE> 18</DL> 19<H2>Arguments</H2> 20<TABLE border="1" width="100%"> 21 <TBODY> 22 <TR> 23 <TD width="13%"><EM><STRONG>dmaNo</STRONG></EM></TD> 24 <TD width="87%">New DMA channel to use (0–3)</TD> 25 </TR> 26 <TR> 27 <TD width="13%"><EM><STRONG>dest</STRONG></EM></TD> 28 <TD width="87%">The transfer destination address</TD> 29 </TR> 30 <TR> 31 <TD width="13%"><EM><STRONG>unit</STRONG></EM></TD> 32 <TD width="87%">One-time transfer size (width * line count)</TD> 33 </TR> 34 <TR> 35 <TD width="13%"><EM><STRONG>length</STRONG></EM></TD> 36 <TD width="87%">Total size to transfer (frame size)</TD> 37 </TR> 38 </TBODY> 39</TABLE> 40 41<H2>Return Values</H2> 42<P>None.</P> 43 44<H2>Description</H2> 45<P> 46Receives frame data from the camera buffer.<BR><BR> 47This function internally uses a new DMA to receive data. See the <code><A href="../mi/ndma/MI_NDmaCopy.html">MI_NDmaCopy</A></code> function for more detailed descriptions of a new DMA.<BR><BR> 48The width and line count used when finding the one-time transfer size will indicate the number of bytes transferred for a single line and the number of lines transferred at once, respectively.<BR> 49One pixel takes up two bytes, so multiply the width by 2 to calculate the number of bytes to transfer. The width is the same as the one set by the <code><A href="CAMERA_SetTrimmingParams.html">CAMERA_SetTrimmingParams</A></code> function if it is called, and the <code><A href="CAMERA_I2CSize.html">CAMERA_I2CSize*</A></code> functions otherwise. (It will be the width of the default camera resolution value if none of these functions have been called. See the <A href="about_camera.html"><B>Overview</B></A> for more information on default values.)Calculate the number of lines using the line count set with the <code><A href="CAMERA_SetTransferLines.html">CAMERA_SetTransferLines</A></code> function. The default line count is 1 if it has not been set by the <code><A href="CAMERA_SetTransferLines.html">CAMERA_SetTransferLines</A></code> function. In addition, adjust the one-time transfer size that is ultimately specified to be 2 KB (1024 pixels) or less. <BR><BR>Some example code is shown below. 50<BLOCKQUOTE><B>Example:</B><BR> 51<BR> 52<PRE>#define WIDTH 256<BR> 53#define HEIGHT 192 54 55CAMERA_SetTrimmingParamsCenter(WIDTH, HEIGHT, 320, 240); 56CAMERA_SetTrimming(TRUE); 57CAMERA_SetTransferLines(CAMERA_GET_MAX_LINES(WIDTH)); /* 256*4=1024 pixels */ 58 59. 60. 61. 62 63CAMERA_DmaRecv(0, buffer, CAMERA_GetBytesAtOnce(WIDTH), CAMERA_GET_FRAME_BYTES(WIDTH, HEIGHT));</PRE></BLOCKQUOTE> 64</P> 65 66<H2>See Also</H2> 67<P><CODE><A href="CAMERA_DmaRecvAsync.html">CAMERA_DmaRecvAsync</A>, <A href="CAMERA_SetTransferLines.html">CAMERA_SetTransferLines</A>, <A href="CAMERA_SetTrimmingParams.html">CAMERA_SetTrimmingParams</A>, <A href="CAMERA_SetTrimming.html">CAMERA_SetTrimming</A>, <A href="CAMERA_I2CSize.html">CAMERA_I2CSize*</A>, <A href="CAMERA_GetBytesAtOnce.html">CAMERA_GetBytesAtOnce</A>, <A href="CAMERA_GET_FRAME_BYTES.html">CAMERA_GET_FRAME_BYTES</A>, <A href="CAMERA_GET_MAX_LINES.html">CAMERA_GET_MAX_LINES</A></CODE></P> 68<H2>Revision History</H2> 69<P> 702008/09/11 Changed the sample code. <br>2007/11/14 Revised explanations for specifying the width. <BR>2007/10/22 Added explanations. <BR>2007/10/02 Initial version.</P> 71<hr><p>CONFIDENTIAL</p></body> 72</HTML> 73
