DSP中i2c存储eeprom实例分析

1示例程序中几种状态说明第一次看i2c_eeprom示例程序，对程序中的MsgStatus信息状态切换非常懵懂，为什 么要有这几个状态？状态切换顺序如何安排？ 一大堆的状态，让人有些摸不着头脑。先把程 序中的头文件-涉及的7种状态分析一下。/ I2C Message Commands for I2CMSG struct#define I2C_MSGSTAT_INACTIVE0x0000未激活状态：一般成功发送数据或者/接受数据后可以设置信息状态为此状态，告诉用户可进行下一次的写数据或读数据。#define I2C_MSGSTAT_SEND_WITHSTOP0x0010 /发送带停止位数据：这是为写数据而设/的状态，写入地址和数据之后发个停止位告诉存储器数据写入完毕。#define I2C_MSGSTAT_WRITE_BUSY0x0011 写数据忙状态：在将待写的数据放入/缓存后，就可以使能IIC传输数据了，然后把信息状态设为该状态，意在告诉用户：数据 /已经在传送过程中。当然是否传送完毕，还需要通过查询SCD位来判断。#define I2C_MSGSTAT_SEND_NOSTOP0x0020/发送无停止位数据：这个状态是为了读/取数据而设的，有查阅过AT24C1024EEPROM存储器使用手册的读者知道，在读数据之前 /要发送数据的地址，发完地址不能产生停止位，这是存储器硬件设计决定的。设为这个状 /态意在告诉读者，可以发送要读取的数据的地址了。#define I2C_MSGSTAT_SEND_NOSTOP_BUSY 0x0021/发送无停止位数据忙状态：这个状态是 /为了读取数据而设的，似于I2C_MSGSTAT_WRITE_BUSY,说明地址数据已经在传送过程中。 传送是否成功，还要看ARDY的状态。#define I2C_MSGSTAT_RESTART0x0022/重发开始位状态：这个状态也是为读取/数据而设。我们知道，读取存储器数据主要分两个步骤：第一，发送START位+设备地址 /+数据地址+无停止位。第二，再发START位+设备地址，紧接着存储器发送数据到IIC接收 缓存器（I2CDRR）,接收到设定好的数据数量（I2CCNT值）时输出停止位STOP./值得注意的是：理论上写完数据就能马上读取数据，但事实上EEPROM存储器仍需要一 /定延时来存储数据，约有2ms左右。通过示波器可以观察到，写完数据后，并不能马上 /成功读取数据，也就是说读数据的第一步骤要重复好几次（总线为50K时，大约要重复 /8次）才能成功。#define I2C_MSGSTAT_READ_BUSY0x00237读取数据忙状态：这个状态是为读取数据而设。在读数据的第二步骤中，发完START位+设备地址后，就设为这一状态。意在说 /明IIC开始等待接收固定数量（I2CCNT值）的数据。可以通过查询ARDY位判断。/头文件中的其他定义应该没什么大问题了！2. AT24C1024 EEPROM读写数据格式（1）AT24C1024 设备地址：10100A1P0R/W（2）单字节写入：START -发送从设备地址（写控制码R/W=0）-处理Ack - 发送字节地址- 处理Ack -发送1字节数据- 处理Ack - STOP。如下 图：_ _STOPSDA LINEVJHIDEVICE TADDRESS FMOST SIGNIFICANT WORD ADDRESSLEASTSIGNIFICANT WORD ADDRESSMSBACKR/_wRoACKLSBACKLBACK（3）按页写入：START-发送从设备地址（写控制码R/W=0）-处理Ack -发 送字节地址- 处理Ack -发送1字节数据- 处理Ack-发送第2字节数 据- 处理Ack-发送第3字节数据- 处理Ack直到发完X字节- STOPo 如下图。注意，连续写入的数据字节数不能超过每页所能容下的总量。如果写入 的数据超过一页的长度，将发生回卷，即从EEPR0M的0地址处进行数据覆盖。 比如，AT24C1024有512页，每页最大容纳256字节。超过这个长度，地址指针 将从每页首地址重新开始。STARTDEVICEADDRESSTEWORD ADDRESS.WOHO ADDRESS (n)1 1 1 1 1 1 1 1 1 1 1 1111 IlliMOSTLEAST罰 GN IFICANTSliMPCANTDATA (n)STOP -MSBACKR/_w cPACKLSBACKL s BACKACK（4）随机单字节读取：第一步：发START -发送从设备地址（写控制码R/W=0） -处理Ack -发送字节地址高位- 处理Ack -发送字节地址低位- 处理 Ack-第二步：发START -发送器件地址（读控制码R/W=1）-处理Ack -接 收1字节数据- STOP。SDA L NEA MSBDEVICEADOAESSwriteHtgh ByteL咖ADDRESSAQDFtESSfl,STARTEVIGEADDHESSREADSTOPACKR/w- QPAck.LSBDATA n N口WHITE（5）随机连续读取：在随机单字节读取操作的STOP信号发送之前，加入若干个 -发送Ack -接收1字节数据即可实现。$0* LlKtRQEUICETT ADDFB9ELow 日ADDRESS:DEVICE R ADDRESShead)1PJWY WRITEackACKN-c ACK（6）当前位置单字节读取：START -发送从设备地址（读控制码）- 处理Ack -发送字节地址- 处理Ack -接收1字节数据- STOP。当前指的是之前 进行过读取操作但是没有发送STOP信号，EEPROM芯片内部指针所在的位置即为 当前位置。READ3口LINEDATA（7）当前位置连续读取：在当前位置单节读取操作的STOP信号发送之前，加入 若干个- 发送Ack -接收1字节数据即可实现。STARTREAD|q11 V r J 厂 1111|1IJJ|jdJ11li11111J1) J|I1JLl11cDATA nAC备注：部分内容引用百度文库中的I2C读写流程文档3.主程序说明及流程图详细的注释可以参见程序附录，这里主要解释一下设备地址取0x50的缘由。从AT24C1024的数据手册可知，设备地址为10100州Pa。而在程序中设置的地址是0x50，即0B0101 0000。看似不妥，其实，这个例子中设备地址采用7位地址 模式，这样只取0x5 0的低7位作为设备地址的高七位，设备地址的最低位R/W则由寄存器 I2CMDR中的TRX位决定。这样读数据时设备地址为0B1010 0001，写数据时设备地址改为 0B1010 0000。通过示波器可以验证这些数据。问题1：每次检测到SCD中断时，也就是顺利发完指定数量的数据或者接收指定数量的数据了， 理论上l2caRegs.l2CCNT=0,但是本人设了几个中断点去观察该寄存器的值，发现总是不为 零。通过观察 l2caRegs . I2CFFTX .bit. TXFFST 和 l2caRegs . l2CFFRX.bit .RXFFST, 可 以发现这两个寄存器为零时，l2caRegs . I2CCNT也不为零。由此可知，I2CCNT不能实时反映 发送/接收存储器中数据的数量，不过可以用TXFFST/RXFFST来代替。图1主程序流程图，图2为写数据程序流程图，图3为读数据程序流程图，图4为中断 函数流程图。a.更改当前指针为：I2cMsgInlb.令I2cMsgInl 状态=I2C MSGSTAT READ BUSYI2CA WriteData 函数返回：I2C STP NOT READY ERROR配置从设备地址返回 I2C BUS BUSY ERROR配置 I2CCNT；地址数据放入缓存;信息数据放入缓存:配置I2CMDR返回I2CSUCCESS图 1 主程序流程图图 2 写数据程序流程图图3 读数据程序流程图中断i2c_in/1a_isr获取中断源：IntS-Y令I2cMsgOu tl当前状态 =I2C MSGSTAT INACTIVE当前状态MSGSTAT WRITE中断源C SCDI2cMsgIn1当前状态MSGSTAT SEND NOSTOPNY令I2cMsgIn 1当前状态 =I2C MSGSTAT SEND NOSTOPI2cMsgIn1当前状态=I2C MSGSTAT READ BU令I2cMsgIn 1当前状态=i2c msgStat inactive从接收缓存器I2CDRR读取数据N -r彳进入fail死循环彳进入 Pass 死循环数据处理：计正确次数和错误次数中断返冋中断源停止仿真CK=1?设置IIC产生STOP位;清除NACK；N当前状态MSGSTAT SEND NOSTOP令当前状态-I2C MISGSTAT RE START图 4 中断函数流程图4.程序附录可以用以下代码替换示例程序Example_280xl2c_eeprom.c中的代码，再进行调试。/该程序跟原始程序没多大区别，主要改变为：引入几个统计变量，改变发送数据长度为2字节/ TI File $Revision: /main/5 $/ Checkin $Date: April 4, 2007 17:18:36 $/#/ FILE: Example_280xI2c_eeprom.c/ TITLE: DSP280x I2C EEPROM Example/ ASSUMPTIONS:/ This program requires the DSP280x header files./ This program requires an external I2C EEPROM connected to/ the I2C bus at address 0x50./As supplied, this project is configured for boot to SARAM/ operation. The 280x Boot Mode table is shown below./ For information on configuring the boot mode of an eZdsp,/please refer to the documentation included with the eZdsp,/ Boot GPIO18 GPIO29 GPIO34/Mode SPICLKA SCITXDA/Flash11/SCI-A11/SPI-A10/I2C-A10/ECAN-A01/SARAM01/OTP00/I/0000/SCITXB101010 - boot to SARAM1/ DESCRIPTION:/ This program will write 1-14 words to EEPROM and read them back. / The data written and the EEPROM address written to are contained / in the message structure, I2cMsgOut1. The data read back will be / contained in the message structure I2cMsgIn1./CODE MODIFICATIONS ARE REQUIRED FOR 60 MHZ DEVICES (In/ DSP280x_Examples.h in the common/include/ directory, set/#define CPU_FRQ_60MHZ to 1, and #define CPU_FRQ_100MHZ to 0)./ /This program will work with the on-board I2C EEPROM supplied on/ the F280x eZdsp./# / Original Author: D.F./ $TI Release: DSP280x Header Files V1.60 $/ $Release Date: December 3, 2007 $/#include DSP280x_Device.h / DSP280x Headerfile Include File#include DSP280x_Examples.h / DSP280x Examples Include File/ Note: I2C Macros used in this example can be found in the/ DSP280x_I2C_defines.h file/ Prototype statements for functions found within this file.void I2CA_Init(void);Uint16 I2CA_WriteData(struct I2CMSG *msg);Uint16 I2CA_ReadData(struct I2CMSG *msg);interrupt void i2c_int1a_isr(void);void pass(void);void fail(void);#define I2C_SLAVE_ADDR0x50 /EEPROM 地址#define I2C_NUMBYTES2/ 为方便示波器观察，设置发送 2 字节的数据#define I2C_EEPROM_HIGH_ADDR0x11 /数据的写入地址高位#define I2C_EEPROM_LOW_ADDR0x0F /数据的写入地址低位/ Global variables/全局变量/ Two bytes will be used for the outgoing address,/有 2 个字节是地址/ thus only setup 14 bytes maximum/最多只能设置 14 字节数据struct I2CMSG l2cMsgOut1二I2C_MSGSTAT_SEND_WITHSTOP 初始状态为：发送带停止位数据I2C_SLAVE_ADDR,I2C_NUMBYTES,I2C_EEPROM_HIGH_ADDR,I2C_EEPROM_LOW_ADDR,0xff,/ Msg Byte 010x3F,/ Msg Byte 020x56,/ Msg Byte 030x78,/ Msg Byte 040x9A,/ Msg Byte 050xBC,/ Msg Byte 060xDE,/ Msg Byte 070xF0,/ Msg Byte 080x11,/ Msg Byte 090x10,/ Msg Byte 100x11,/ Msg Byte 110x12,/ Msg Byte 120x13,/ Msg Byte 130x12,/ Msg Byte 14;struct I2CMSG I2cMsgIn1= I2C_MSGSTAT_SEND_NOSTOP,I2C_SLAVE_ADDR,I2C_NUMBYTES,I2C_EEPROM_HIGH_ADDR,I2C_EEPROM_LOW_ADDR;struct I2CMSG *CurrentMsgPtr;/ Used in interruptsUint16 PassCount;Uint16 FailCount;Uint16 ARDY_ISRC_NACK_number=0; /统计 ARDY 中断源引起的中断中 NACK 次数Uint16 SCD_ISRC_number=0;统计SCD中断源引起的中断次数Uint16 ARDY_ISRC_number=0;/统计 ARDY 中断源引起的中断次数Uint16 all_ISRC_number=0;/统计所有中断源引起的中断次数Uint16 Write_load_num=0;/统计写数据函数调用次数Uint16 Read_load_num1=0;/统计读数据函数调用次数 1 第一步骤Uint16 Read_load_num2=0;/统计读数据函数调用次数 2 第二步骤void main(void)Uint16 Error;Uint16 i;CurrentMsgPtr = &I2cMsgOut1;/ Step 1. Initialize System Control:/ PLL, WatchDog, enable Peripheral Clocks / This example function is found in the DSP280x_SysCtrl.c file.InitSysCtrl();/ Step 2. Initalize GPIO:/ This example function is found in the DSP280x_Gpio.c file and/ illustrates how to set the GPIO to its default state./ InitGpio();/ Setup only the GP I/O only for I2C functionalityInitI2CGpio();/ Step 3. Clear all interrupts and initialize PIE vector table:/ Disable CPU interruptsDINT;/ Initialize PIE control registers to their default state./ The default state is all PIE interrupts disabled and flags/ are cleared./ This function is found in the DSP280x_PieCtrl.c file.InitPieCtrl();/ Disable CPU interrupts and clear all CPU interrupt flags:IER = 0x0000;IFR = 0x0000;/ Initialize the PIE vector table with pointers to the shell Interrupt/ Service Routines (ISR)./ This will populate the entire table, even if the interrupt/ is not used in this example. This is useful for debug purposes./ The shell ISR routines are found in DSP280x_DefaultIsr.c./ This function is found in DSP280x_PieVect.c.InitPieVectTable();/ Interrupts that are used in this example are re-mapped to/ ISR functions found within this file.EALLOW;/ This is needed to write to EALLOW protected registersPieVectTable.I2CINT1A = &i2c_int1a_isr;EDIS;/ This is needed to disable write to EALLOW protected registers/ Step 4. Initialize all the Device Peripherals:/ This function is found in DSP280x_InitPeripherals.c/ InitPeripherals(); / Not required for this exampleI2CA_Init();/ Step 5. User specific code/ Clear CountersPassCount = 0;FailCount = 0;/ Clear incoming message bufferfor (i = 0; i SlaveAddress;/ Check if bus busyif (I2caRegs.I2CSTR.bit.BB = 1)return I2C_BUS_BUSY_ERROR;/判断总线空闲后进行数据发送/ Setup number of bytes to send/ MsgBuffer + AddressI2caRegs.I2CCNT = msg-NumOfBytes+2; /递减/ Setup data to sendI2caRegs.I2CDXR = msg-MemoryHighAddr;I2caRegs.I2CDXR = msg-MemoryLowAddr;/ for (i=0; iNumOfBytes-2; i+)for (i=0; iNumOfBytes; i+)I2caRegs.I2CDXR = *(msg-MsgBuffer+i);/ Send start as master transmitterI2caRegs.I2CMDR.all = 0x6E20; / 按以下参数配置 IIC 并使能 IIC/【ObOIIO 1110 0010 OOOO, NACKMOD=0, FREE=1中断产生时IIC能继续运行，STT=1产生开始位】/【STP=1产生停止位,MST=1主模式,TRX=1发送，XA=0七位地址模式，RM=0不重复,DLB=0无回路，IRS=1使能I2C模块，STB=0,FDF=0】/开始发送数据, I2CCNT 递减模式统计数据到达 0时产生中断,且产生停止位注意：TRX决定AT24C1024设备地址中的R/W，这里R/W=0写数据模式return I2C_SUCCESS;Uint16 I2CA_ReadData(struct I2CMSG *msg) 要完成一次读数据任务：要产生两个START位，产生第1个START位之后发送设备地址和数据地址；产生第2个START位之后写入设备地址，并开始接收存储器提供的数据。/ Wait until the STP bit is cleared from any previous master communication./ Clearing of this bit by the module is delayed until after the SCD bit is/ set. If this bit is not checked prior to initiating a new message, the/ I2C could get confused.if (I2caRegs.I2CMDR.bit.STP = 1)return I2C_STP_NOT_READY_ERROR;I2caRegs.I2CSAR = msg-SlaveAddress;if(msg-MsgStatus = I2C_MSGSTAT_SEND_NOSTOP) /产生第一个 START 位之后发送设备地址和数据地址/ Check if bus busyif (I2caRegs.I2CSTR.bit.BB = 1)return I2C_BUS_BUSY_ERROR;l2caRegs.l2CCNT = 2;/设置发送数据字节数-递减模式-等0时可以允许产生stop位(若使能STP)l2caRegs.l2CDXR = msg-MemoryHighAddr; 发送要读取数据的开始地址l2caRegs.l2CDXR = (msg-MemoryLowAddr);I2caRegs.I2CMDR.all = 0x2620;/ 按以下参数配置 IIC 并使能 IIC/【STT =1发送起始位，STP=0不产生停止位，MST=1主模式,TRX=1发送,IRS=1使能I2C模块】/ 开始发送数据 I2CCNT 递减模式统计数据到达0时产生中断，但是没有产生停止位注意：TRX决定AT24C1024设备地址中的R/W,这里R/W=0写数据else if(msg-MsgStatus = I2C_MSGSTAT_RESTART)/y产生第2个START位之后发送设备地址，然后开始接收存储器提供的数据/I2caRegs.I2CCNT = msg-NumOfBytes; / 设置数据接收字节数量I2caRegs.I2CMDR.all = 0x2C20;/ 按以下参数配置 IIC 并使能 IIC/【STT =1发送起始位,STP=1产生停止位,MST=1主模式,TRX=0接收,IRS=1使能I2C模块】开始接收数据，I2CCNT递减模式统计数据到达0时产生中断，有产生停止位注意-TRX决定AT24C1024设备地址中的R/W,这里R/W=1读数据return I2C_SUCCESS;/到此说明发送地址/读取数据成功interrupt void i2c_int1a_isr(void)/ I2C-AUint16 IntSource, i;all_ISRC_number+; 统计所有中断次数/ Read interrupt sourceIntSource = I2caRegs.I2CISRC.all;/ Interrupt source = stop condition detected if(IntSource = I2C_SCD_ISRC)SCD_ISRC_number+;/ If completed message was writing data, reset msg to inactive stateif (CurrentMsgPtr-MsgStatus = I2C_MSGSTAT_WRITE_BUSY)CurrentMsgPtr-MsgStatus = I2C_MSGSTAT_INACTIVE;发送完成，便换为未启动状态；说明可以进行下一次写数据else/ If a message receives a NACK during the address setup portion of the/ EEPROM read, the code further below included in the register access ready/ interrupt source code will generate a stop condition. After the stop/ condition is received (here), set the message status to try again./ User may want to limit the number of retries before generating an error.if(CurrentMsgPtr-MsgStatus = I2C_MSGSTAT_SEND_N0ST0P_BUSY)发送无停止位地址忙CurrentMsgPtr-MsgStatus = I2C_MSGSTAT_SEND_N0ST0P;更新为发送停止位状态，可允许下一发送地址/ If completed message was reading EEPROM data, reset msg to inactive state/ and read data from FIFO.else if (CurrentMsgPtr-MsgStatus = I2C_MSGSTAT_READ_BUSY) 读数据忙状态，说明可对接收缓存器I2CDRR进行接收数据读取了CurrentMsgPtr-MsgStatus = I2C_MSGSTAT_INACTIVE;/设为未启状态动，再读数据，这样允许下一次写数据到 EEPROMfor(i=0; i MsgBufferi = I2caRegs.I2CDRR;/ Check recieved data /读完接收到的数据，接下来进行判断数据是否准确for(i=0; i MsgStatus = l2C_MSGSTAT_SEND_NOSTOP_BUSY)CurrentMsgPtr-MsgStatus = I2C_MSGSTAT_RESTART;/更新为重发 START位状态，为接收数据准备 / end of register access readyelse/ Generate some error due to invalid interrupt source asm( ESTOP0);/ Enable future I2C (PIE Group 8) interruptsPieCtrlRegs.PIEACK.all = PIEACK_GROUP8; /重启中断允许void pass()asm( ESTOP0);for(;);void fail()asm( ESTOP0);for(;);/=