我打算使用TI F28335开发板读取一个湿度传感器的数据，通过I2C 通信。 我附上修改后的程序（基于TI官方的给F28335写的I2C的一个例子程序），发现这个例子程序并不可以运行。每次都是卡在 while(I2caRegs.I2CSTR.bit.XRDY == 0); // wait until first byte is out 这条语句无线循环，并不能继续执行下去。这个问题困扰我很久，是因为这个例子程序本身就有问题吗？还是因为其他原因？ 这个传感器我目前使用的datasheet的PDF文件链接如下：https://www.pololu.com/file/0J721/HTU21D(F).pdf 方便您参考。 通信中使用的register还有地址我都严格按照datasheet上面所说应该都没有问题，build这个程序过程中也并没有报错，所以完全不知道我这个程序问题出在哪里。 传感器我使用的是adafruit家已经做好的breakout board，应该已经包括pull up resistor。 这个硬件链接在这里：https://learn.adafruit.com/adafruit-htu21d-f-temperature-humidity-sensor/overview
//
// Lab12_2: TMS320F28335
// (C) Frank Bormann
//
//###########################################################################
//
// FILE: Lab12_2.c
//
// TITLE: DSP28335 I2C test
// Temperature Sensor TMP100 connected to GPIO33 (SCL) and GPIO32(SDA)
// LED GPIO34 as life indicator 100 ms toggle
// 12 bit mode of TMP100, 1/16 degree celcius resolution
// use watch window for variable "temperature" (type int; qvalue:8)
//###########################################################################
//
// Ver | dd mmm yyyy | Who | Description of changes
// =====|=============|======|===============================================
// 3.0 | 24 Jul 2009 | F.B. | Lab12_1 F28335; Header-files Version 1.20
// 3.1 | 15 Nov 2009 | F.B | Lab12_1 for F28335 @30MHz and PE revision 5
//###########################################################################
#include "DSP2833x_Device.h"
#define SLAVE_Address 0x40
#define SLAVE_Write 0x80
#define SLAVE_READ 0x81
#define SLAVE_Write_humidity 0xE5
// external function prototypes
extern void InitSysCtrl(void);
extern void InitPieCtrl(void);
extern void InitPieVectTable(void);
extern void InitCpuTimers(void);
extern void ConfigCpuTimer(struct CPUTIMER_VARS *, float, float);
// Prototype statements for functions found within this file.
void Gpio_select(void);
void I2CA_Init(void);
interrupt void cpu_timer0_isr(void);
int Value_Read;
//###########################################################################
// main code
//###########################################################################
void main(void)
{
InitSysCtrl(); // Basic Core Init from DSP2833x_SysCtrl.c
EALLOW;
SysCtrlRegs.WDCR= 0x00AF; // Re-enable the watchdog
EDIS; // 0x00AF to NOT disable the Watchdog, Prescaler = 64
DINT; // Disable all interrupts
Gpio_select(); // GPI031-LED2, GPIO34-LED3 as output
// to 2 LEDs on F28335 control-card
I2CA_Init(); // Initialize I2C device slave address is issued in I2CA_Init() 0x29
// step 1 : do the configuration:
//----------------------------------------------------//
// Send START, set pointer to Configuration register and set resolution to 12 bit
//hence it is master-transmitter mode to write register to the sensor
//step 1.1 set integration time to address 0x01+0xFF (2.4ms)
//step 1.2 set gain to address 0x0F + 0x00 (1*gain)
//step 1.3 Enable Device to address 0x00+0x03
I2caRegs.I2CCNT = 2; // means the DXR includes 2 byte including POINTER_CONFIGURATION and 0x60 for data bit setting
I2caRegs.I2CDXR = SLAVE_Write;// address for writing
I2caRegs.I2CMDR.all = 0x6E20; //0x6E20 convert to binary is 0110111000100000
/*
Bit15 = 0; no NACK in receiver mode
Bit14 = 1; FREE on emulation halt
Bit13 = 1; STT generate START
Bit12 = 0; reserved
Bit11 = 1; STP generate STOP
Bit10 = 1; MST master mode
Bit9 = 1; TRX ****master - transmitter mode****
Bit8 = 0; XA 7 bit address mode
Bit7 = 0; RM nonrepeat mode, I2CCNT determines # of bytes
Bit6 = 1; DLB no loopback mode.it should be '0', from slide 12-12 corrected by Alex.J.
Bit5 = 1; IRS I2C module enabled
Bit4 = 0; STB no start byte mode
Bit3 = 0; FDF no free data format
Bit2-0: 0; BC **** 8 bit per data byte****
*/
while(I2caRegs.I2CSTR.bit.XRDY == 0); // wait until first byte is out
I2caRegs.I2CDXR = SLAVE_Write_humidity ; /*0xE5 read humidity */
while(I2caRegs.I2CSTR.bit.SCD == 0); // wait for STOP condition
I2caRegs.I2CSTR.bit.SCD = 1; //clear stop condition flag
InitPieCtrl(); // basic setup of PIE table; from DSP2833x_PieCtrl.c
InitPieVectTable(); // default ISR's in PIE
EALLOW;
PieVectTable.TINT0 = &cpu_timer0_isr;
EDIS;
InitCpuTimers(); // basic setup CPU Timer0, 1 and 2
ConfigCpuTimer(&CpuTimer0,150,100000);
PieCtrlRegs.PIEIER1.bit.INTx7 = 1;
IER |=1;
EINT;
ERTM;
CpuTimer0Regs.TCR.bit.TSS = 0; // start timer0
//step 2 : start read the sensor data including 1 byte pointer register==>2 byte sensor data (upper 8bit) + (lower 8bit)
while(1)
{
while(CpuTimer0.InterruptCount == 0);
CpuTimer0.InterruptCount = 0;
EALLOW;
SysCtrlRegs.WDKEY = 0x55; // service WD #1
EDIS;
// Send START and set pointer to temperature - register
I2caRegs.I2CCNT = 1; // pointer to temperature register, count 1 bit only
I2caRegs.I2CDXR = SLAVE_READ;// address for reading
// Send start as master transmitter
I2caRegs.I2CMDR.all = 0x6620; //only change stop to '0', do not generate stop. all others are the same as 6E20
/* Bit15 = 0; no NACK in receiver mode
Bit14 = 1; FREE on emulation halt
Bit13 = 1; STT generate START
Bit12 = 0; reserved
Bit11 = 0; STP not generate STOP
Bit10 = 1; MST master mode
Bit9 = 1; TRX master - transmitter mode
Bit8 = 0; XA 7 bit address mode
Bit7 = 0; RM nonrepeat mode, I2CCNT determines # of bytes
Bit6 = 1; DLB no loopback mode ,it should be '0', corrected by alex.J
Bit5 = 1; IRS I2C module enabled
Bit4 = 0; STB no start byte mode
Bit3 = 0; FDF no free data format
Bit2-0: 0; BC 8 bit per data byte,000 */
while(I2caRegs.I2CSTR.bit.ARDY == 0); // 0=previous cycle has not completed, wait for access ready condition
I2caRegs.I2CCNT = 1; // read 2 byte temperature
I2caRegs.I2CMDR.all = 0x6C20; //only change bit9 to 0, means master-receiver mode
/* Bit15 = 0; no NACK in receiver mode
Bit14 = 1; FREE on emulation halt
Bit13 = 1; STT generate START
Bit12 = 0; reserved
Bit11 = 1; STP generate STOP
Bit10 = 1; MST master mode
Bit9 = 0; TRX master - receiver mode
Bit8 = 0; XA 7 bit address mode
Bit7 = 0; RM nonrepeat mode, I2CCNT determines # of bytes
Bit6 = 0; DLB no loopback mode
Bit5 = 1; IRS I2C module enabled
Bit4 = 0; STB no start byte mode
Bit3 = 0; FDF no free data format
Bit2-0: 0; BC 8 bit per data byte */
while(I2caRegs.I2CSTR.bit.RRDY == 0); //0 means receive data NOT available in 12CDRR, wait for 1st byte
Value_Read = I2caRegs.I2CDRR; // read 8 Bit (integers)
// RRDY is automatically cleared by read of I2CDRR
GpioDataRegs.GPBTOGGLE.bit.GPIO34 = 1; // toggle red LED LD3 @ 28335CC
GpioDataRegs.GPATOGGLE.bit.GPIO31 = 1;
}
}
void Gpio_select(void)
{
EALLOW;
GpioCtrlRegs.GPAMUX1.all = 0; // GPIO15 ... GPIO0 = General Puropse I/O
GpioCtrlRegs.GPAMUX2.all = 0; // GPIO31 ... GPIO16 = General Purpose I/O
GpioCtrlRegs.GPBMUX1.all = 0; // GPIO47 ... GPIO32 = General Purpose I/O
GpioCtrlRegs.GPBMUX1.bit.GPIO32 = 1; // GPIO32 = I2C - SDA
GpioCtrlRegs.GPBMUX1.bit.GPIO33 = 1; // GPIO33 = I2C - SCL
GpioCtrlRegs.GPBPUD.bit.GPIO32 = 0; // Enable pull-up for GPIO32 (SDAA)
GpioCtrlRegs.GPBPUD.bit.GPIO33 = 0; // Enable pull-up for GPIO33 (SCLA)
GpioCtrlRegs.GPBQSEL1.bit.GPIO32 = 3; // Asynch input GPIO32 (SDAA)
GpioCtrlRegs.GPBQSEL1.bit.GPIO33 = 3; // Asynch input GPIO33 (SCLA)
GpioCtrlRegs.GPBMUX2.all = 0; // GPIO63 ... GPIO48 = General Purpose I/O
GpioCtrlRegs.GPCMUX1.all = 0; // GPIO79 ... GPIO64 = General Purpose I/O
GpioCtrlRegs.GPCMUX2.all = 0; // GPIO87 ... GPIO80 = General Purpose I/O
GpioCtrlRegs.GPADIR.all = 0; // GPIO0 to 31 as inputs
// GpioCtrlRegs.GPADIR.bit.GPIO9 = 1; // GPIO9 = LED LD1
GpioCtrlRegs.GPADIR.bit.GPIO31 = 1; // GpIO11 = LED LD2
GpioCtrlRegs.GPBDIR.all = 0; // GPIO63-32 as inputs
GpioCtrlRegs.GPBDIR.bit.GPIO34 = 1; // peripheral explorer: LED LD3 at GPIO34
//GpioCtrlRegs.GPBDIR.bit.GPIO49 = 1; // peripheral explorer: LED LD4 at GPIO49
GpioCtrlRegs.GPCDIR.all = 0; // GPIO87-64 as inputs
EDIS;
}
void I2CA_Init(void)
{
I2caRegs.I2CMDR.bit.IRS = 0; // Reset the I2C module
// I2C slave address register
I2caRegs.I2CSAR = SLAVE_Address;
// I2C Prescale Register
I2caRegs.I2CPSC.all = 14; // Internal I2C module clock = SYSCLK/(PSC +1)
// = 10 MHz
I2caRegs.I2CCLKL = 95; // Tmaster = (PSC +1)[ICCL + 5 + ICCH + 5] / 150MHz
I2caRegs.I2CCLKH = 95; // Tmaster = 10 [ICCL + ICCH + 10] / 150 MHz
// d = 5 for IPSC >1
// for I2C 50 kHz:
// Tmaster = 20 µs *150 MHz / 10 = 200 = (ICCL + ICCH +10)
// ICCL + ICCH = 190
// ICCL = ICH = 190/2 = 95
// I2caRegs.I2CCLKL = 45;
// I2caRegs.I2CCLKH = 45; // for I2C 100 kHz:
// Tmaster = 10 µs *150 MHz / 10 = 100 = (ICCL + ICCH + 10)
// ICCL + ICCH = 90
// ICCL = ICH = 90/2 = 45
I2caRegs.I2CMDR.bit.IRS = 1; // Take I2C out of reset
}
interrupt void cpu_timer0_isr(void)
{
CpuTimer0.InterruptCount++;
EALLOW;
SysCtrlRegs.WDKEY = 0xAA; // service WD #2
EDIS;
PieCtrlRegs.PIEACK.all = PIEACK_GROUP1;
}
//===========================================================================
// End of SourceCode.
//===========================================================================
