口袋实验室–使用 AD2 高效调试 IIC 接口

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目录

1. 简介

2. 软件工具介绍

2.1 Logic

2.2 Protocol

2.2.1 Master 模式

2.2.2 Spy 模式

3. 调试 Si5338

3.1 简要步骤

3.2 Si5338 寄存器配置流程

3.3 AD2的基本配置

3.4 检查Si5338状态

3.5 配置Si5338寄存器

3.6 保存Si5338寄存器

4. 总结

1. 简介

本文分享使用 AD2 快速调试 I2C 设备的案例。

• 通过 Waveform 读写 EEPROM。
• 通过 Javascript 脚本配置 Si5338 芯片。

I2C接口

I2C（Inter-Integrated Circuit）接口是一种高度灵活的通信协议，通过仅使用两条线（即数据线SDA 和时钟线 SCL）实现了多个设备间的数据传输。

Si5338芯片

Si5338 可以生成四个独立的时钟信号，每个输出时钟都可以独立配置以支持各种信号格式和供电电压。这使得它非常适合在有限空间内实现多频率合成。Si5338 具有极低的抖动性能。它广泛应用于网络、通讯、高性能计算等领域，特别是在需要精确时钟信号的场合。Si5338通过I2C接口进行配置和控制，可以灵活地设置输出频率、相位和其他参数，满足不同应用的需求。

2. 软件工具介绍

Waveform 中包含三个与 I2C 接口相关的工具模块：

• Logic：逻辑分析仪。
• Protocol：相当于数字模式发生器和逻辑分析仪的组合。
• Script：直接使用脚本控制硬件。

2.1 Logic

可以单独使用 Logic Analyzer 捕获波形，也可以联合 Protocol 一起使用。

在 I2C 触发向导中，可以指定以下选项：

• 触发：选择在 I2C 开始、停止、任何 ACK/NACK 和特定地址、读/写、确认以及数据选项之间进行选择。
• 地址/数据：指定连续的地址和数据值，或选择忽略它。
• 读/写：选择读取、写入或忽略操作类型。
• 确认：选择 ACK、NAK 或忽略确认。

2.2 Protocol

2.2.1 Master 模式

Master Mode 用于创建完整的读写传输。

假设你有一个 I2C 设备地址为 0x50，想要将 1 2 3 h45 b 这五个数据写入到该设备的 0x02 开始的寄存器，可以这样配置：

• Clock Stretching 是 I2C 协议中的一个机制，允许从设备在需要更多时间处理数据时，将时钟信号（SCL 线）保持在低电平，从而暂停与主设备的通信。当从设备准备好继续通信时，它会释放时钟信号，主设备检测到这一点后，继续数据传输。这个机制也用于处理速度不同的设备之间的通信，不过 Clock Stretching 也可能导致总线带宽降低。

注意：一般情况下，需要关闭 Clock Stretching。

2.2.2 Spy 模式

• 监听模式用于解码 I2C 通信。
• Filter 选项用于指定要记录的地址和（读或写）操作。
• FreqFilte r启用接收频率过滤器，以消除信号上的干扰。指定的频率用于过滤掉10%的干扰，例如对于100kHz的脉冲，短于1微秒的将被忽略。
• 齿轮下拉菜单包含启用时间戳的选项。

3. 调试 Si5338

3.1 简要步骤

连接设备：首先，将AD2的逻辑分析仪通道连接到Si5338芯片的I2C接口上，确保SDA和SCL线分别对应。可以利用AD2提供的电源功能给Si5338供电。

配置WaveForms软件：启动AD2随附的WaveForms软件，并配置逻辑分析仪工具以适应I2C协议的特定参数，如时钟速度等。WaveForms软件能够自动识别并解码I2C通信，大大简化了调试过程。

捕获和分析数据：在Si5338进行通信时，使用AD2捕获I2C总线上的数据。通过WaveForms软件，可以实时查看和分析数据传输过程，包括启动条件、地址帧、数据帧和停止条件等。

调试和优化：根据捕获的数据，可以对Si5338的配置进行调整和优化。如果发现通信错误或性能不佳的问题，可以通过分析I2C总线上的数据来定位问题源头，并进行相应的调整。

调试中的注意事项：

• 确保AD2与Si5338之间的连接稳定可靠，避免在数据传输过程中出现干扰或误操作。
• 注意观察I2C总线的电气特性，如上拉电阻的配置，以确保通信的稳定性和可靠性。

3.2 Si5338 寄存器配置流程

了解 Si5338 寄存器配置流程是接下来使用AD2进行调试的基础。

3.3 AD2的基本配置

需要开启两个功能模块：

• Protocol，用于开启AD2的IIC物理层
• Script，用于编写Javascript脚本，实现上一节所描述Si5338配置流程

3.4 检查Si5338状态

//Check Si5338 Status clear(); print("start\n"); if (Protocol.I2C.Clear() != true) throw "I2C bus error. Check the pull-ups."; var dev_addr = 0x70; var reg_addr = 218; var reg_data = Protocol.I2C.Read(dev_addr, 1, [reg_addr]); if ((reg_data & 0x10) == 0) print("PLL_LOL = 0, PLL is locked.\n"); else print("PLL_LOL = 1, PLL is loss of locked.\n"); if ((reg_data & 0x08) == 0) print("LOS_FDBK = 0, Present of Signal Feedback Input.\n"); else print("LOS_FDBK = 1, Loss Of Signal Feedback Input.\n"); if ((reg_data & 0x04) == 0) print("LOS_CLKIN = 0, Present of Signal Clock Input.\n"); else print("LOS_CLKIN = 1, Loss Of Signal Clock Input.\n"); if ((reg_data & 0x01) == 0) print("SYS_CAL = 0, PLL is in process of acquiring lock.\n"); else print("SYS_CAL = 1, PLL is not acquiring lock.\n"); print("end");

3.5 配置Si5338寄存器

//C0 - 125MHz, lvds //C1 - 160MHz, lvds //C2 - 100MHz, lvds //C3 - 50MHz, lvds clear(); print("start"); if (Protocol.I2C.Clear() != true) throw "I2C bus error. Check the pull-ups."; var dev_addr = 0x71; var reg_addr = 0 ; var reg_data = 0 ; var reg_data_t = 0 ; var curr = new Array(3); var reg_store = [ [ 0,0x00,0x00], [ 1,0x00,0x00], [ 2,0x00,0x00], [ 3,0x00,0x00], [ 4,0x00,0x00], [ 5,0x00,0x00], [ 6,0x08,0x1D], [ 7,0x00,0x00], [ 8,0x70,0x00], [ 9,0x0F,0x00], [ 10,0x00,0x00], [ 11,0x00,0x00], [ 12,0x00,0x00], [ 13,0x00,0x00], [ 14,0x00,0x00], [ 15,0x00,0x00], [ 16,0x00,0x00], [ 17,0x00,0x00], [ 18,0x00,0x00], [ 19,0x00,0x00], [ 20,0x00,0x00], [ 21,0x00,0x00], [ 22,0x00,0x00], [ 23,0x00,0x00], [ 24,0x00,0x00], [ 25,0x00,0x00], [ 26,0x00,0x00], [ 27,0x71,0x80], [ 28,0x15,0xFF], [ 29,0x90,0xFF], [ 30,0xB0,0xFF], [ 31,0xC0,0xFF], [ 32,0xC0,0xFF], [ 33,0xC0,0xFF], [ 34,0xC0,0xFF], [ 35,0xAA,0xFF], [ 36,0x06,0x1F], [ 37,0x06,0x1F], [ 38,0x06,0x1F], [ 39,0x06,0x1F], [ 40,0x84,0xFF], [ 41,0x10,0x7F], [ 42,0x24,0x3F], [ 43,0x00,0x00], [ 44,0x00,0x00], [ 45,0x00,0xFF], [ 46,0x00,0xFF], [ 47,0x14,0x3F], [ 48,0x2A,0xFF], [ 49,0x05,0xFF], [ 50,0xC4,0xFF], [ 51,0x07,0xFF], [ 52,0x10,0xFF], [ 53,0x00,0xFF], [ 54,0x08,0xFF], [ 55,0x00,0xFF], [ 56,0x00,0xFF], [ 57,0x00,0xFF], [ 58,0x00,0xFF], [ 59,0x01,0xFF], [ 60,0x00,0xFF], [ 61,0x00,0xFF], [ 62,0x00,0x3F], [ 63,0x10,0xFF], [ 64,0xD0,0xFF], [ 65,0x05,0xFF], [ 66,0x00,0xFF], [ 67,0x00,0xFF], [ 68,0x00,0xFF], [ 69,0x00,0xFF], [ 70,0x08,0xFF], [ 71,0x00,0xFF], [ 72,0x00,0xFF], [ 73,0x00,0x3F], [ 74,0x10,0xFF], [ 75,0x80,0xFF], [ 76,0x0A,0xFF], [ 77,0x00,0xFF], [ 78,0x00,0xFF], [ 79,0x00,0xFF], [ 80,0x00,0xFF], [ 81,0x01,0xFF], [ 82,0x00,0xFF], [ 83,0x00,0xFF], [ 84,0x00,0x3F], [ 85,0x10,0xFF], [ 86,0x00,0xFF], [ 87,0x17,0xFF], [ 88,0x00,0xFF], [ 89,0x00,0xFF], [ 90,0x00,0xFF], [ 91,0x00,0xFF], [ 92,0x01,0xFF], [ 93,0x00,0xFF], [ 94,0x00,0xFF], [ 95,0x00,0x3F], [ 96,0x10,0x00], [ 97,0x2A,0xFF], [ 98,0x66,0xFF], [ 99,0x08,0xFF], [100,0x00,0xFF], [101,0x00,0xFF], [102,0x00,0xFF], [103,0x03,0xFF], [104,0x00,0xFF], [105,0x00,0xFF], [106,0x80,0xBF], [107,0x00,0xFF], [108,0x00,0xFF], [109,0x00,0xFF], [110,0x80,0xFF], [111,0x00,0xFF], [112,0x00,0xFF], [113,0x00,0xFF], [114,0x80,0xFF], [115,0x00,0xFF], [116,0x80,0xFF], [117,0x00,0xFF], [118,0x80,0xFF], [119,0x00,0xFF], [120,0x00,0xFF], [121,0x00,0xFF], [122,0x80,0xFF], [123,0x00,0xFF], [124,0x00,0xFF], [125,0x00,0xFF], [126,0x00,0xFF], [127,0x00,0xFF], [128,0x00,0xFF], [129,0x00,0x0F], [130,0x00,0x0F], [131,0x00,0xFF], [132,0x00,0xFF], [133,0x00,0xFF], [134,0x00,0xFF], [135,0x00,0xFF], [136,0x00,0xFF], [137,0x00,0xFF], [138,0x00,0xFF], [139,0x00,0xFF], [140,0x00,0xFF], [141,0x00,0xFF], [142,0x00,0xFF], [143,0x00,0xFF], [144,0x00,0xFF], [145,0x00,0x00], [146,0xFF,0x00], [147,0x00,0x00], [148,0x00,0x00], [149,0x00,0x00], [150,0x00,0x00], [151,0x00,0x00], [152,0x00,0xFF], [153,0x00,0xFF], [154,0x00,0xFF], [155,0x00,0xFF], [156,0x00,0xFF], [157,0x00,0xFF], [158,0x00,0x0F], [159,0x00,0x0F], [160,0x00,0xFF], [161,0x00,0xFF], [162,0x00,0xFF], [163,0x00,0xFF], [164,0x00,0xFF], [165,0x00,0xFF], [166,0x00,0xFF], [167,0x00,0xFF], [168,0x00,0xFF], [169,0x00,0xFF], [170,0x00,0xFF], [171,0x00,0xFF], [172,0x00,0xFF], [173,0x00,0xFF], [174,0x00,0xFF], [175,0x00,0xFF], [176,0x00,0xFF], [177,0x00,0xFF], [178,0x00,0xFF], [179,0x00,0xFF], [180,0x00,0xFF], [181,0x00,0x0F], [182,0x00,0xFF], [183,0x00,0xFF], [184,0x00,0xFF], [185,0x00,0xFF], [186,0x00,0xFF], [187,0x00,0xFF], [188,0x00,0xFF], [189,0x00,0xFF], [190,0x00,0xFF], [191,0x00,0xFF], [192,0x00,0xFF], [193,0x00,0xFF], [194,0x00,0xFF], [195,0x00,0xFF], [196,0x00,0xFF], [197,0x00,0xFF], [198,0x00,0xFF], [199,0x00,0xFF], [200,0x00,0xFF], [201,0x00,0xFF], [202,0x00,0xFF], [203,0x00,0x0F], [204,0x00,0xFF], [205,0x00,0xFF], [206,0x00,0xFF], [207,0x00,0xFF], [208,0x00,0xFF], [209,0x00,0xFF], [210,0x00,0xFF], [211,0x00,0xFF], [212,0x00,0xFF], [213,0x00,0xFF], [214,0x00,0xFF], [215,0x00,0xFF], [216,0x00,0xFF], [217,0x00,0xFF], [218,0x00,0x00], [219,0x00,0x00], [220,0x00,0x00], [221,0x0D,0x00], [222,0x00,0x00], [223,0x00,0x00], [224,0xF4,0x00], [225,0xF0,0x00], [226,0x00,0x00], [227,0x00,0x00], [228,0x00,0x00], [229,0x00,0x00], [231,0x00,0x00], [232,0x00,0x00], [233,0x00,0x00], [234,0x00,0x00], [235,0x00,0x00], [236,0x00,0x00], [237,0x00,0x00], [238,0x14,0x00], [239,0x00,0x00], [240,0x00,0x00], [242,0x02,0x02], [243,0xF0,0x00], [244,0x00,0x00], [245,0x00,0x00], [247,0x00,0x00], [248,0x00,0x00], [249,0xA8,0x00], [250,0x00,0x00], [251,0x84,0x00], [252,0x00,0x00], [253,0x00,0x00], [254,0x00,0x00], [255, 1, 0xFF], // set page bit to 1 [ 0,0x00,0x00], [ 1,0x00,0x00], [ 2,0x00,0x00], [ 3,0x00,0x00], [ 4,0x00,0x00], [ 5,0x00,0x00], [ 6,0x00,0x00], [ 7,0x00,0x00], [ 8,0x00,0x00], [ 9,0x00,0x00], [ 10,0x00,0x00], [ 11,0x00,0x00], [ 12,0x00,0x00], [ 13,0x00,0x00], [ 14,0x00,0x00], [ 15,0x00,0x00], [ 16,0x00,0x00], [ 17,0x01,0x00], [ 18,0x00,0x00], [ 19,0x00,0x00], [ 20,0x90,0x00], [ 21,0x31,0x00], [ 22,0x00,0x00], [ 23,0x00,0x00], [ 24,0x01,0x00], [ 25,0x00,0x00], [ 26,0x00,0x00], [ 27,0x00,0x00], [ 28,0x00,0x00], [ 29,0x00,0x00], [ 30,0x00,0x00], [ 31,0x00,0xFF], [ 32,0x00,0xFF], [ 33,0x01,0xFF], [ 34,0x00,0xFF], [ 35,0x00,0xFF], [ 36,0x90,0xFF], [ 37,0x31,0xFF], [ 38,0x00,0xFF], [ 39,0x00,0xFF], [ 40,0x01,0xFF], [ 41,0x00,0xFF], [ 42,0x00,0xFF], [ 43,0x00,0x0F], [ 44,0x00,0x00], [ 45,0x00,0x00], [ 46,0x00,0x00], [ 47,0x00,0xFF], [ 48,0x00,0xFF], [ 49,0x01,0xFF], [ 50,0x00,0xFF], [ 51,0x00,0xFF], [ 52,0x90,0xFF], [ 53,0x31,0xFF], [ 54,0x00,0xFF], [ 55,0x00,0xFF], [ 56,0x01,0xFF], [ 57,0x00,0xFF], [ 58,0x00,0xFF], [ 59,0x00,0x0F], [ 60,0x00,0x00], [ 61,0x00,0x00], [ 62,0x00,0x00], [ 63,0x00,0xFF], [ 64,0x00,0xFF], [ 65,0x01,0xFF], [ 66,0x00,0xFF], [ 67,0x00,0xFF], [ 68,0x90,0xFF], [ 69,0x31,0xFF], [ 70,0x00,0xFF], [ 71,0x00,0xFF], [ 72,0x01,0xFF], [ 73,0x00,0xFF], [ 74,0x00,0xFF], [ 75,0x00,0x0F], [ 76,0x00,0x00], [ 77,0x00,0x00], [ 78,0x00,0x00], [ 79,0x00,0xFF], [ 80,0x00,0xFF], [ 81,0x00,0xFF], [ 82,0x00,0xFF], [ 83,0x00,0xFF], [ 84,0x90,0xFF], [ 85,0x31,0xFF], [ 86,0x00,0xFF], [ 87,0x00,0xFF], [ 88,0x01,0xFF], [ 89,0x00,0xFF], [ 90,0x00,0xFF], [ 91,0x00,0x0F], [ 92,0x00,0x00], [ 93,0x00,0x00], [ 94,0x00,0x00], [255, 0, 0xFF] ]; // set page bit to 0 //End of file //Disable all outputs; Set OEB_ALL = 1; reg230[4]; print("Disable all outputs"); reg_addr = 230; reg_data = 0x10; Protocol.I2C.Write(dev_addr, [ reg_addr, reg_data ]); //Pause LOL; Set DIS_LOL = 1; reg241[7]; print("Pause PLL loss of lock detect."); reg_addr = 241; reg_data = 0xE5; Protocol.I2C.Write(dev_addr, [ reg_addr, reg_data ]); //Write register map; print("Writing register map."); for (var i = 0; i < 350-1; i++) { curr = reg_store[i]; if (curr[2] != 0x00) { //do a read-modify-write reg_addr = curr[0]; reg_data = Protocol.I2C.Read(dev_addr, 1, [reg_addr]); // read current value reg_data = reg_data & ~curr[2]; //clear current value reg_data = reg_data | (curr[1] & curr[2]); //set new value Protocol.I2C.Write(dev_addr, [ reg_addr, reg_data ]); } } // check LOS alarm for the xtal input // on IN1 and IN2 (and IN3 if necessary) reg_addr = 218; reg_data = Protocol.I2C.Read(dev_addr, 1, [reg_addr]); reg_data = reg_data & 0x04; while (reg_data != 0) { reg_data = Protocol.I2C.Read(dev_addr, 1, [reg_addr]); reg_data = reg_data & 0x04; } print("Xtal input exists."); //FCAL_OVRD_EN = 0 print("Disable override Frequency Calibration."); reg_addr = 49; reg_data = Protocol.I2C.Read(dev_addr, 1, [reg_addr]); reg_data = reg_data & 0x7F; Protocol.I2C.Write(dev_addr, [ reg_addr, reg_data ]); //Soft reset print("Soft reset"); reg_addr = 246; reg_data = 0x02; Protocol.I2C.Write(dev_addr, [ reg_addr, reg_data ]); //DIS_LOL = 0 print("Continue PLL loss of lock detect"); reg_addr = 241; reg_data = 0x65; Protocol.I2C.Write(dev_addr, [ reg_addr, reg_data ]); //Wait 25ms wait(0.025); //Make sure the device locked by checking PLL_LOL and SYS_CAL reg_addr = 218; reg_data = Protocol.I2C.Read(dev_addr, 1, [reg_addr]); reg_data = reg_data & 0x15; while (reg_data != 0) { reg_data = Protocol.I2C.Read(dev_addr, 1, [reg_addr]); reg_data = reg_data & 0x15; } print("PLL is locked and acquiring lock completed"); //Copy FCAL value to active registers print("Copy FCAL value to active registers"); reg_addr = 235; reg_data = Protocol.I2C.Read(dev_addr, 1, [reg_addr]); reg_addr = 45; Protocol.I2C.Write(dev_addr, [ reg_addr, reg_data ]); reg_addr = 236; reg_data = Protocol.I2C.Read(dev_addr, 1, [reg_addr]); reg_addr = 46; Protocol.I2C.Write(dev_addr, [ reg_addr, reg_data ]); reg_addr = 237; reg_data = Protocol.I2C.Read(dev_addr, 1, [reg_addr]); reg_addr = 47; reg_data_t = Protocol.I2C.Read(dev_addr, 1, [reg_addr]); reg_data = (reg_data & 3) | (reg_data_t & 0xFC); Protocol.I2C.Write(dev_addr, [ reg_addr, reg_data ]); //Set PLL to FCAL values; Set FCAL_OVRD_EN = 1; reg49[7]; print("Set PLL to FCAL values, override Frequency Calibration for the VCO"); reg_addr = 49; reg_data = Protocol.I2C.Read(dev_addr, 1, [reg_addr]); reg_data = reg_data | 0x80; Protocol.I2C.Write(dev_addr, [ reg_addr, reg_data ]); //Enable Outputs; Set OEB_ALL = 0; reg 230[4]; print("Enable Outputs"); reg_addr = 230; reg_data = Protocol.I2C.Read(dev_addr, 1, [reg_addr]); reg_data = reg_data & ~0x10; Protocol.I2C.Write(dev_addr, [ reg_addr, reg_data ]); reg_addr = 218; reg_data = Protocol.I2C.Read(dev_addr, 1, [reg_addr]); if ((reg_data & 0x10) == 0) { print("\n*PLL_LOL = 0, PLL is locked.*\n"); print("*Config Si5338 Success.*"); } print("end");

3.6 保存Si5338寄存器

//遍历Si5338寄存器，并存储到指定txt文件 clear(); print("start"); if (Protocol.I2C.Clear() != true) throw "I2C bus error. Check the pull-ups."; const rom_len = 350; var filepath = "D:/Si5338/tt.txt"; var data = new Array(rom_len); var addr = 0; FileWrite(filepath, ""); //Clear all exist content Protocol.I2C.Write(0x70, [ 255, 0 ]); for(addr = 0; addr < 255; addr++) { data[addr] = Protocol.I2C.Read(0x70, 1, [addr]); FileAppendLine(filepath, addr + "," + data[addr]); print(addr, data[addr]); } Protocol.I2C.Write(0x70, [ 255, 1 ]); for(addr = 0; addr < rom_len - 255; addr++) { data[addr] = Protocol.I2C.Read(0x70, 1, [addr]); FileAppendLine(filepath, (255+addr) + "," + data[addr]); print(255+addr, data[addr]); } print("end");

4. 总结

通过上述步骤和注意事项，使用Digilent AD2调试Si5338芯片或其他基于I2C接口的设备将变得简单高效。AD2不仅提供了强大的捕获和分析能力，而且通过其直观的用户界面和丰富的功能，极大地降低了调试低速接口的难度，提高了开发效率。无论是学生、爱好者还是专业工程师，AD2都是进行电子设计和调试的理想工具。