MPR121 can not communction

[xuebinzhang]

 I try to use mcu communcate the MPR121 ,raed all registers ,get 0xff.if somewhere wrong ? Have anyoneelse met this problem? My configration follow :

void mpr121QuickConfig(void) {
I2C_Write(0x80, 0x63);
I2C_Write(0x5e, 0x00);
// Section A
// This group controls filtering when data is > baseline.
//unsigned char para[4]={1,1,0,0};
//HalSensorWriteReg(MHD_R, para, 4);
I2C_Write(MHD_R, 0x01);
I2C_Write(NHD_R, 0x01);
I2C_Write(NCL_R, 0x00);
I2C_Write(FDL_R, 0x00);
// Section B
// This group controls filtering when data is < baseline.
//unsigned char para1[4]={1,1,0xff,0x02};
//HalSensorWriteReg(MHD_F, para1, 4);
I2C_Write(MHD_F, 0x01);
I2C_Write(NHD_F, 0x01);
I2C_Write(NCL_F, 0xFF);
I2C_Write(FDL_F, 0x02);
// Section C
// This group sets touch and release thresholds for each electrode
// unsigned char para2[24]={TOU_THRESH,REL_THRESH,TOU_THRESH,REL_THRESH,TOU_THRESH,REL_THRESH,TOU_THRESH,REL_THRESH,TOU_THRESH,REL_THRESH,TOU_THRESH,REL_THRESH,TOU_THRESH,REL_THRESH,TOU_THRESH,REL_THRESH
// ,TOU_THRESH,REL_THRESH,TOU_THRESH,REL_THRESH,TOU_THRESH,REL_THRESH,TOU_THRESH,REL_THRESH};
// HalSensorWriteReg(ELE0_T, para2, 24);
I2C_Write(ELE0_T, TOU_THRESH);
I2C_Write(ELE0_R, REL_THRESH);
I2C_Write(ELE1_T, TOU_THRESH);
I2C_Write(ELE1_R, REL_THRESH);
I2C_Write(ELE2_T, TOU_THRESH);
I2C_Write(ELE2_R, REL_THRESH);
I2C_Write(ELE3_T, TOU_THRESH);
I2C_Write(ELE3_R, REL_THRESH);
I2C_Write(ELE4_T, TOU_THRESH);
I2C_Write(ELE4_R, REL_THRESH);
I2C_Write(ELE5_T, TOU_THRESH);
I2C_Write(ELE5_R, REL_THRESH);
I2C_Write(ELE6_T, TOU_THRESH);
I2C_Write(ELE6_R, REL_THRESH);
I2C_Write(ELE7_T, TOU_THRESH);
I2C_Write(ELE7_R, REL_THRESH);
I2C_Write(ELE8_T, TOU_THRESH);
I2C_Write(ELE8_R, REL_THRESH);
I2C_Write(ELE9_T, TOU_THRESH);
I2C_Write(ELE9_R, REL_THRESH);
I2C_Write(ELE10_T, TOU_THRESH);
I2C_Write(ELE10_R, REL_THRESH);
I2C_Write(ELE11_T, TOU_THRESH);
I2C_Write(ELE11_R, REL_THRESH);
// Section D
// Set the Filter Configuration
// Set ESI2
// unsigned char para3[2]={4,12};
//HalSensorWriteReg(FIL_CFG, para3, 2);
I2C_Write(FIL_CFG, 0x04);
// Section E
// Electrode Configuration
// Enable 6 Electrodes and set to run mode
// I2C_Write(ELE_CFG, 0x06); // Enable first 6 electrodes
// Section F
// Enable Auto Config and auto Reconfig
// unsigned char para4[4]={0x0b,0xc9,0x82,0xb5};
//HalSensorWriteReg(FIL_CFG, para4, 4);
I2C_Write(ATO_CFG0, 0x0B);
I2C_Write(ATO_CFGU, 0xC9); // USL = (Vdd-0.7)/vdd*256 = 0xC9 @3.3V
I2C_Write(ATO_CFGL, 0x82); // LSL = 0.65*USL = 0x82 @3.3V
I2C_Write(ATO_CFGT, 0xB5); // Target = 0.9*USL = 0xB5 @3.3V
// Set ELE_CFG to 0x00 to return to standby mode //
I2C_Write(ELE_CFG, 0x0C); // Enables all 12 Electrodes
}

the read function is

void ReadTouchKey(unsigned char *readbuffer)
{
unsigned char read[3];
read[0]=Read_Add(0x00,0xb4);

read[1]=Read_Add(0x01,0xb4);
read[2]=Read_Add(0x5e,0xb4);
*readbuffer=*read;
*(readbuffer+1)=*(read+1);
*(readbuffer+2)=*(read+2);
} 

I hope get useful suggestion.

Thank you.