Synaptics RMI4 Multitouch PAD

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Synaptics RMI4 Multitouch PAD

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MarkDing
Contributor I


Connection

  • NOTE: nINT is an active-low open-drain pin for which the host must supply an external pull-up resistor.
    DISP2_DAT9        --->  Touch_nINT DISPB2_SER_CLK    --->  Touch_I2C_DAT DISPB2_SER_DIO    --->  Touch_I2C_CLK EIM_A16           --->  Touch_nRST1 

Touch PAD register.

Part of register map, that we need concern.

AddrNameBit 7Bit 6Bit 5Bit 4Bit 3Bit 2Bit 1Bit 0
0x0014Interrupt status    Abs0ButtonStatusFlash
0x0015Button data       Left
AddrNameBit 7Bit 6Bit 5Bit 4Bit 3 - Bit 2Bit 1 - Bit 0
0x00162D Finger State    Finger State 1Finger State 0
AddrNameBit 7 - Bit 0
0x00172D X position (11:4) Finger 0X position [11:4]
0x00182D Y position (11:4) Finger 0Y position [11:4]
0x001B2D Z Finger 0Z
0x001C2D X position (11:4) Finger 1X position [11:4]
0x001D2D Y position (11:4) Finger 1Y position [11:4]
0x00202D Z Finger 1Z
AddrNameBit 7 - Bit 4Bit 3 - Bit 0
0x00192D Y/X position(3:0) Finger 0Y Position [3:0]X Position [3:0]
0x001A2D Wy/Wx Finger 0WyWx
0x001E2D Y/X position(3:0) Finger 1Y Position [3:0]X Position [3:0]
0x001F2D Wy/Wx Finger 1WyWx

Get touch sample.

  I2CReadForTimes(0x2c,0x14,buf,0x11); // read out register value from register addr 0x14.   ts_sample->int_state = buf[0] & 0xF; // save interrupt status   ts_sample->button_data = buf[1] & 0x01; // save button_data      switch(buf[0x2] & 0xf) // 2D Finger State   {     case 0x0:  ts_sample->contact_resistance = 0;   break;     case 0x01:     case 0x02:  // bit0-1 is Finger 0 state       ts_sample->contact_resistance = 1;   ts_sample->x_position = (((buf[3]<<4))|(buf[5]&0xf));      ts_sample->y_position = (((buf[4])<<4)|((buf[5]&0xf0)>>4));  break;     case 0x04:     case 0x08: // bit2-3 is Finger 1 state        ts_sample->contact_resistance = 1;   ts_sample->x_position = (((buf[8]<<4))|(buf[10]&0xf));     ts_sample->y_position = (((buf[9])<<4)|((buf[10]&0xf0)>>4));         break;     case 0x05:     case 0x06:     case 0x09:     case 0x0a: // Finger 0 and Finger 1 press at same time      ts_sample->contact_resistance = 2;   ts_sample->x_position = (((buf[3]<<4))|(buf[5]&0xf));      ts_sample->y_position = (((buf[4])<<4)|((buf[5]&0xf0)>>4));          ts_sample->x2_position = (((buf[8]<<4))|(buf[10]&0xf));    ts_sample->y2_position = (((buf[9])<<4)|((buf[10]&0xf0)>>4));                break;      default :       printk("fail buf[0x16] = %d \n",buf[2]); // report real finger state value    return -1;   }   

Transfer to screen pixel relate position. We use 480x800 for example

  if(ts_sample.int_state & 0x08) { // touch screen abs     if (ts_sample.contact_resistance < 2) {       if (ts_sample.x_position == 0 && ts_sample.y_position == 0 &&    ts_sample.contact_resistance == 0) {    x = last_x;     y = last_y;       }       else       {// transfer to screen relate position         x = ts_sample.x_position * 480 / 1894;          y = 799 - ts_sample.y_position * 800 / 3245;       }       if (x != last_x) {         input_report_abs(mxc_inputdev, ABS_X, x);       last_x = x;       }       if (y != last_y) {  input_report_abs(mxc_inputdev, ABS_Y, y);       last_y = y;       }       /* report pressure */       input_report_abs(mxc_inputdev, ABS_PRESSURE, ts_sample.contact_resistance);       /* report the BTN_TOUCH */       if (ts_sample.contact_resistance != last_press)       {      input_event(mxc_inputdev, EV_KEY,BTN_TOUCH, ts_sample.contact_resistance);       }     }     input_sync(mxc_inputdev);     last_press = ts_sample.contact_resistance;   }   else if(ts_sample.int_state & 0x04)  // button input   {     input_report_key(input_button,KEY_MENU,ts_sample.button_data);   } 
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LinhNguyen
Contributor III

MarkDing‌ Hi Mark,

I'm bringing up RMI4 Synaptics S3351 touch driver, but I have issue that the IC was configured by RMI4 driver but never detect any touch (no interrupt in attention signal, and reading touch status F12 shows no touches). 

Do you have any guess on my issue? 

Thank you & happy new year.

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