PDF《Preliminary》

3 倍索引模式. 双工滑条中传感器对 的电容应该合理匹配 (不超过

10 pF) . 当您选择双工时,CSDAUTO 向导将自动生成双工传感器索引表. 此表说明了不同滑条段计数的双工序列: Table 1. 不同滑条段计数的双工序列 滑条段总计数 段序列

10 0,1,2,3,4,0,3,1,4,2

12 0,1,2,3,4,5,0,3,1,4,2,5

14 0,1,2,3,4,5,6,0,3,6,1,4,2,5

16 0,1,2,3,4,5,6,7,0,3,6,1,4,7,2,5

18 0,1,2,3,4,5,6,7,8,0,3,6,1,4,7,2,5,8

20 0,1,2,3,4,5,6,7,8,9,0,3,6,9,1,4,7,2,5,8 [+] Feedback Autotuning CapSense Sigma-Delta Document Number: 001-65686 Rev. ** Page

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32 22 0,1,2,3,4,5,6,7,8,9,10,0,3,6,9,1,4,7,10,2,5,8

24 0,1,2,3,4,5,6,7,8,9,10,11,0,3,6,9,1,4,7,10,2,5,8,11

26 0,1,2,3,4,5,6,7,8,9,10,11,12,0,3,6,9,12,1,4,7,10,2,5,8,11

28 0,1,2,3,4,5,6,7,8,9,10,11,12,13,0,3,6,9,12,1,4,7,10,13,2,5,8,11

30 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,0,3,6,9,12,1,4,7,10,13,2,5,8,11,14

32 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,0,3,6,9,12,15,1,4,7,10,13,2,5,8,11,14

34 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,0,3,6,9,12,15,1,4,7,10,13,16,2,5,8,11,14

36 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,0,3,6,9,12,15,1,4,7,10,13,16,2,5,8,11,14,17

38 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,0,3,6,9,12,15,18,1,4,7,10,13,16,2,5,8,11 ,14,17

40 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,0,3,6,9,12,15,18,1,4,7,10,13,16,19,2, 5,8,11,14,17

42 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,0,3,6,9,12,15,18,1,4,7,10,13,16,19 ,2,5,8,11,14,17,20

44 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,0,3,6,9,12,15,18,21,1,4,7,10,13 ,16,19,2,5,8,11,14,17,20

46 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,0,3,6,9,12,15,18,21,1,4,7,10 ,13,16,19,22,2,5,8,11,14,17,20

48 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,0,3,6,9,12,15,18,21,1,4,7 ,10,13,16,19,22,2,5,8,11,14,17,20,23

50 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,0,3,6,9,12,15,18,21,24 ,1,4,7,10,13,16,19,22,2,5,8,11,14,17,20,23

52 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,0,3,6,9,12,15,18,21 ,24,1,4,7,10,13,16,19,22,25,2,5,8,11,14,17,20,23

54 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,0,3,6,9,12,15,18 ,21,24,1,4,7,10,13,16,19,22,25,2,5,8,11,14,17,20,23,26

56 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,0,3,6,9,12,15 ,18,21,24,27,1,4,7,10,13,16,19,22,25,2,5,8,11,14,17,20,23,26 滑条段总计数 段序列 [+] Feedback Autotuning CapSense Sigma-Delta Document Number: 001-65686 Rev. ** Page

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32 插值和定标 在滑条传感器和触摸板应用中,经常有必要在具体传感器的本质间距以上确定出手指 (或其他电容性物 体)的位置. 手指在滑条传感器或触摸板上的接触区域通常大于任何单个的传感器. 为了采用一个质心来计算插值后的位置,首先对阵列进行扫描以验证所给定的传感器位置是否有效. 这要 求一定数量的相邻传感器信号大于某一噪声阈值. 在找到最为强烈的信号后,此信号和那些大于噪声阈值 的邻近信号均用于计算质心. 按以下形式计算质心时,最少要用两个,最多要用八个 (典型情况下)传感 器来计算质心位置: Equation

1 计算得出的值通常是分数. 为了能够采用某一特定分辨率来报告质心 (例如对于

12 个传感器为

0 到100 的范围) ,要将质心值乘以计算得出的标量. 将插值和定标操作结合到同一项计算内并在想要的标量 内直接报告其结果,可以达到更高的效率. 这一过程可以在高层 API 内进行处理. 滑条传感器数量和分辨率均在 CSDAUTO 向导中设置. 向导将计算出标量数值并以分数值的形式进行存储. 质心分辨率的乘数包含在三个字节中,且具有以下位定义: 使用以下公式计算分辨率: 分辨率 = (传感器数量 C 1)* 乘数 质心值限制为 24-bit 的无符号整数,而且其分辨率是传感器数量和乘数的函数. 外部组件选择指南 CSDAUTO 可使用内部或外部调制电容 Cmod,由Vss 接地连接到 P0[1] 或P0[3] 端口引脚. 通过 引脚 选择向导 设置可选择引脚. 所选引脚不得用于其他任何用途. 除非 CSDAUTO 可以兼容内部电容,否则建议使用外部电容. 外部调制电容的建议值为 2.2 nF. 可通过实 验选择最佳电容值,以获得最大信噪比. 2.2 nF 的电容值在多数情况下都能产生良好结果. 应使用陶瓷 电容. 温度电容系数并不重要. 分辨率乘数最高有效位 位76543210乘数