Synaptics RMI4 Multitouch PAD

[MarkDing]

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.

Addr	Name	Bit 7	Bit 6	Bit 5	Bit 4	Bit 3	Bit 2	Bit 1	Bit 0
0x0014	Interrupt status					Abs0	Button	Status	Flash
0x0015	Button data								Left

Addr	Name	Bit 7	Bit 6	Bit 5	Bit 4	Bit 3 - Bit 2	Bit 1 - Bit 0
0x0016	2D Finger State					Finger State 1	Finger State 0

Addr	Name	Bit 7 - Bit 0
0x0017	2D X position (11:4) Finger 0	X position [11:4]
0x0018	2D Y position (11:4) Finger 0	Y position [11:4]
0x001B	2D Z Finger 0	Z
0x001C	2D X position (11:4) Finger 1	X position [11:4]
0x001D	2D Y position (11:4) Finger 1	Y position [11:4]
0x0020	2D Z Finger 1	Z

Addr	Name	Bit 7 - Bit 4	Bit 3 - Bit 0
0x0019	2D Y/X position(3:0) Finger 0	Y Position [3:0]	X Position [3:0]
0x001A	2D Wy/Wx Finger 0	Wy	Wx
0x001E	2D Y/X position(3:0) Finger 1	Y Position [3:0]	X Position [3:0]
0x001F	2D Wy/Wx Finger 1	Wy	Wx

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);   } 

[LinhNguyen]

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.