NXTCam是一個即時的影像處理模組，具有內建處理器，並符合NXT標準輸入埠通訊協定的視覺模組。這個介面提供了NXTCam所見高階的、已處理的影像資料。此處理過的資料包含影像中物件的座標，在循線追蹤模式，它的資料包含了線段的座標圖、物件顏色、物件的數量、座標與線段的區塊座標系統。
NXTCam並非送出原始影像到NXT，以USB線連接NXTCam電腦，可透過NXTCamView軟體檢視所見的圖像，透過USB埠傳輸給電腦的解析度可達176*144像素顏色影像。
最大消耗電力
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42mA at
4.7V
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像素
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88*144pixel
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取樣速率
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30fps
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調整焦距
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可
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追蹤物件
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最多可八個物件(須由使用者定義八個不同的顏色)
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I2C使用的腳位為:SDA(1)，GND(2)，SCL(3)，+5V(4)，列出了暫存器位置與設置的指令。
Commands
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Action
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ASCII
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Hex
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A
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0x41
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Sort tracked objects by size
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B
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0x42
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Select Object tracking mode
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C
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0x43
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Write to image sensor Registers
Use CAUTION when using command C
since this can stop NXTCam from working properly. In case this happens,
please power off your NXTCam and power it on again.
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D
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0x44
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Disable Tracking
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E
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0x45
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Enable Tracking
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G
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0x47
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Get the Color map from NXTCam Engine
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H
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0x48
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Read data from the image sensor Registers
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I
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0x49
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Illumination on (Future)
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L
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0x4C
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Select Line tracking mode
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N
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0x4E
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Set ADPA mode ON (setting stored in NVRAM)
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O
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0x4F
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Set ADPA mode Off (default) (setting stored
in
NVRAM)
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P
|
0x50
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Ping NXTCam Engine
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R
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0x52
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Reset NXTCam Engine
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S
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0x53
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Send the color map to NXTCam Engine
|
T
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0x54
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Illumination Off
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U
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0x55
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Sort tracked objects by color
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V
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0x56
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Get NXTCam Engine firmware version
No, Read resulting string at 0x42 (12 bytes).
|
X
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0x58
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Do not Sort tracked objects
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J
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0x4A
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Lock tracking buffer
Tracking is going on
continuously, and while you read buffer may be updated by the tracking
engine. You can issue this command to
Lock the buffer updates. After issuing this command allow 25 milliseconds for
any updates in progress to finish. Then read the tracking information.
|
K
|
0x4B
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Unlock tracking buffer.
If you had locked the buffer before reading, ensure to unlock it after
you are done reading.
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NXTCam模組I2C暫存器位置表
Register
|
Read
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Write
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Comments
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0x00-0x07
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Software version – (Vn.nn)
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-
|
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0x08-0x0f
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Vendor Id – mndsnsrs
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-
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0x10-0x17
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Device ID – NXTCam
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-
|
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0x41
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-
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Command
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This register is command register. A
command written here will be executed.
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0x42
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Number of objects detected
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-
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Shows how many objects are being tracked.
Zero indicates that there are no objects being tracked.
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0x43
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1st object color
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-
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This is the first object color as per the
sorting method selected.
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0x441
|
1st object - X upper left
|
Upper left X coordinate of first object
|
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0x45
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1st object - Y upper left
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Upper left Y coordinate of first object
|
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0x46
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1st object - X lower right
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Lower right X coordinate of first object
|
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0x472
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1st object - Y lower right
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Lower right Y coordinate of first object
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0x48
|
2nd object color
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||
0x49-0x4C
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2nd object co-ordinates
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||
0x4D
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3rd object color
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||
0x4E-0x51
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3rd object co-ordinates
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||
0x52
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4th object color
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||
0x53-0x56
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4th object co-ordinates
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||
0x57
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5th object color
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||
0x58-0x5B
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5th object co-ordinates
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||
0x5C
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6th object color
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||
0x5D-0x60
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6th object co-ordinates
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焦距部分，NXTCam鏡頭設置2~4英尺之間為最佳的焦距，此鏡頭可自由旋轉，本身較緊防止意外地轉動與焦點晃動，輕輕地轉動支架鏡頭即可，不可太過用力，否則可能損壞鏡頭。
內建自動暫停，一旦跟蹤模式開始，程式內讀取NXTCam的對象9秒內必須有動作，如果9秒內沒有動作，跟蹤模式會自動停止。
NXTCam被設計在正常白光的環境下操作，影像擷取偏向紅色，很有可能外界光源與紅光有關，可以試著調整紅光讓影像處理更加精準，進一步的操作可以透過I2C暫存器來改變顏色增益、亮度和NXTCam的對比度。
NXTCam的像素是88X144 。NXTCam有兩種模式─物件追蹤模式(Object tracking mode)與循線模式(Line following mode)。使用物件追蹤模式時，NXTCam會將物體看作一個大方塊，並傳回方塊左上角與右下角的xy座標，我們只要經由簡單的換算便可以得知物體概略位置，而NXTCam最多可以同時追蹤八個不同的物體。在使用循線模式時，NXTCam會將物體切割成好幾個線段，並傳回每個線段兩個端點的xy座標。
