/*
xsns_36_MGC3130.ino - Support for I2C MGC3130 Electric Field Sensor for Sonoff-Tasmota
Copyright (C) 2019 Christian Baars & Theo Arends
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see .
*/
//#define USE_MGC3130
#ifdef USE_I2C
#ifdef USE_MGC3130
/*********************************************************************************************\
* MGC3130 - Electric Field Sensor
*
* Adaption for TASMOTA: Christian Baars
* based on various implementations from Pimoroni, jspark311, hoverlabs and scjurgen
*
* I2C Address: 0x42
*
* Wiring: SDA/SCL as usual plus RESET and TRANSFER -> 4 Wires
\*********************************************************************************************/
#define XSNS_36 36
#warning **** MGC3130: It is recommended to disable all unneeded I2C-drivers ****
#define MGC3130_I2C_ADDR 0x42
#define MGC3130_xfer pin[GPIO_MGC3130_XFER]
#define MGC3130_reset pin[GPIO_MGC3130_RESET]
bool MGC3130_type = false;
char MGC3130stype[8];
#define MGC3130_SYSTEM_STATUS 0x15
#define MGC3130_REQUEST_MSG 0x06
#define MGC3130_FW_VERSION 0x83
#define MGC3130_SET_RUNTIME 0xA2
#define MGC3130_SENSOR_DATA 0x91
#define MGC3130_GESTURE_GARBAGE 1
#define MGC3130_FLICK_WEST_EAST 2
#define MGC3130_FLICK_EAST_WEST 3
#define MGC3130_FLICK_SOUTH_NORTH 4
#define MGC3130_FLICK_NORTH_SOUTH 5
#define MGC3130_CIRCLE_CLOCKWISE 6 //not active in airwheel mode
#define MGC3130_CIRCLE_CCLOCKWISE 7 //not active in airwheel mode
#define MGC3130_MIN_ROTVALUE 0
#define MGC3130_MAX_ROTVALUE 1023
#define MGC3130_MIN_ZVALUE 32768 // if we fly under the radar, we do not report anything
#ifdef USE_WEBSERVER
const char HTTP_MGC_3130_SNS[] PROGMEM =
"{s}" "%s" "{m}%s{e}"
"{s}" "HwRev" "{m}%u.%u{e}"
"{s}" "loaderVer" "{m}%u.%u{e}"
"{s}" "platVer" "{m}%u{e}"; // {s} = | , {m} = | , {e} = |
|---|
#endif // USE_WEBSERVER
/*********************************************************************************************\
* MGC3130
*
* Programmer : MGC3130 Datasheet
\*********************************************************************************************/
#pragma pack(1)
union MGC3130_Union{
uint8_t buffer[132];
struct
{
// header
uint8_t msgSize; // in Bytes
uint8_t flag; //not used
uint8_t counter; // cyclic counter of transmitted messages
uint8_t id; // 0x91 for data output
// payload
struct {
uint8_t DSPStatus:1;
uint8_t gestureInfo:1;
uint8_t touchInfo:1;
uint8_t airWheelInfo:1;
uint8_t xyzPosition:1;
uint8_t noisePower:1;
uint8_t reserved:2;
uint8_t electrodeConfiguration:3;
uint8_t CICData:1;
uint8_t SDData:1;
uint16_t reserved2:3;
} outputConfigMask;
uint8_t timestamp;
struct {
uint8_t positionValid:1;
uint8_t airWheelValid:1;
uint8_t rawDataValid:1;
uint8_t noisePowerValid:1;
uint8_t environmentalNoise:1;
uint8_t clipping:1;
uint8_t reserved:1;
uint8_t DSPRunning:1;
} systemInfo;
uint16_t dspInfo;
struct {
uint8_t gestureCode:8; // 0 -> No Gesture
uint8_t reserved:4;
uint8_t gestureType:4; //garbage, flick or circular
uint8_t edgeFlick:1;
uint16_t reserved2:14;
uint8_t gestureInProgress:1; // If "1" Gesture recognition in progress
} gestureInfo;
struct {
uint8_t touchSouth:1;
uint8_t touchWest:1; //:Bit 01
uint8_t touchNorth:1; //:Bit 02
uint8_t touchEast:1; //:Bit 03
uint8_t touchCentre:1; //:Bit 04
uint8_t tapSouth:1; //:Bit 05
uint8_t tapWest:1; //:Bit 06
uint8_t tapNorth:1; //:Bit 07
uint8_t tapEast :1; //:Bit 08
uint8_t tapCentre:1; //:Bit 09
uint8_t doubleTapSouth:1; //:Bit 10
uint8_t doubleTapWest:1; //:Bit 11
uint8_t doubleTapNorth:1; //:Bit 12
uint8_t doubleTapEast:1; //:Bit 13
uint8_t doubleTapCentre:1; //:Bit 14
uint8_t reserved:1; //:Bit 15
uint8_t touchCounter; //period between the time when the hand starts moving to touch until it is detected
uint8_t reserved2;
} touchInfo;
int8_t airWheel;
uint8_t reserved;
uint16_t x;
uint16_t y;
uint16_t z;
float noisePower;
float CICData[4]; // uncalibrated sensor data
float SDData[4]; // signal deviation
} out;
struct {
uint8_t header[3];
// payload
uint8_t valid;
uint8_t hwRev[2];
uint8_t parameterStartAddr;
uint8_t loaderVersion[2];
uint8_t loaderPlatform;
uint8_t fwStartAddr;
char fwVersion[120];
} fw;
struct{
uint8_t id;
uint8_t size;
uint16_t error;
uint32_t reserved;
uint32_t reserved1;
} status;
} MGC_data;
#pragma pack()
char MGC3130_currentGesture[12];
int8_t MGC3130_delta, MGC3130_lastrotation = 0;
int16_t MGC3130_rotValue, MGC3130_lastSentRotValue = 0;
uint16_t MGC3130_lastSentX, MGC3130_lastSentY, MGC3130_lastSentZ = 0;
uint8_t hwRev[2], loaderVersion[2], loaderPlatform = 0;
char MGC3130_firmwareInfo[20];
uint8_t MGC3130_touchTimeout = 0;
uint16_t MGC3130_touchCounter = 1; // measure how long you touch the surface in loop cycles
uint32_t MGC3130_touchTimeStamp = millis();
bool MGC3130_triggeredByTouch = false;
uint8_t MGC3130_mode = 1; // 1-gesture; 2-airwheel; 3-position
// predefined messages
uint8_t MGC3130autoCal[] = {0x10, 0x00, 0x00, 0xA2, 0x80, 0x00 , 0x00, 0x00, 0x06, 0x00, 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0xFF};
uint8_t MGC3130disableAirwheel[] = {0x10, 0x00, 0x00, 0xA2, 0x90, 0x00 , 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x20, 0x00, 0x00, 0x00};
uint8_t MGC3130enableAirwheel[] = {0x10, 0x00, 0x00, 0xA2, 0x90, 0x00 , 0x00, 0x00, 0x20, 0x00, 0x00, 0x00, 0x20, 0x00, 0x00, 0x00};
void MGC3130_triggerTele(){
mqtt_data[0] = '\0';
if (MqttShowSensor()) {
MqttPublishPrefixTopic_P(TELE, PSTR(D_RSLT_SENSOR), Settings.flag.mqtt_sensor_retain);
#ifdef USE_RULES
RulesTeleperiod(); // Allow rule based HA messages
#endif // USE_RULES
}
}
void MGC3130_handleSensorData(){
if ( MGC_data.out.outputConfigMask.touchInfo && MGC3130_touchTimeout == 0){
if (MGC3130_handleTouch()){
MGC3130_triggeredByTouch = true;
MGC3130_triggerTele();
}
}
if(MGC3130_mode == 1){
if( MGC_data.out.outputConfigMask.gestureInfo && MGC_data.out.gestureInfo.gestureCode > 0){
MGC3130_handleGesture();
MGC3130_triggerTele();
}
}
if(MGC3130_mode == 2){
if(MGC_data.out.outputConfigMask.airWheelInfo && MGC_data.out.systemInfo.airWheelValid){
MGC3130_handleAirWheel();
MGC3130_triggerTele();
}
}
if(MGC3130_mode == 3){
if(MGC_data.out.systemInfo.positionValid && (MGC_data.out.z > MGC3130_MIN_ZVALUE)){
MGC3130_triggerTele();
}
}
}
void MGC3130_sendMessage(uint8_t data[], uint8_t length){
Wire.beginTransmission(MGC3130_I2C_ADDR);
Wire.write(data,length);
Wire.endTransmission();
delay(2);
MGC3130_receiveMessage();
}
void MGC3130_handleGesture(){
//char log[LOGSZ];
char edge[5];
if (MGC_data.out.gestureInfo.edgeFlick){
snprintf_P(edge, sizeof(edge), PSTR("ED_"));
}
else{
snprintf_P(edge, sizeof(edge), PSTR(""));
}
switch(MGC_data.out.gestureInfo.gestureCode){
case MGC3130_GESTURE_GARBAGE:
//snprintf_P(log, sizeof(log), PSTR("NONE"));
snprintf_P(MGC3130_currentGesture, sizeof(MGC3130_currentGesture), PSTR("NONE"));
break;
case MGC3130_FLICK_WEST_EAST:
//snprintf_P(log, sizeof(log), PSTR("%sFL_WE"), edge);
snprintf_P(MGC3130_currentGesture, sizeof(MGC3130_currentGesture), PSTR("%sFL_WE"), edge);
break;
case MGC3130_FLICK_EAST_WEST:
//snprintf_P(log, sizeof(log), PSTR("%sFL_EW"), edge);
snprintf_P(MGC3130_currentGesture, sizeof(MGC3130_currentGesture), PSTR("%sFL_EW"), edge);
break;
case MGC3130_FLICK_SOUTH_NORTH:
//snprintf_P(log, sizeof(log), PSTR("%sFL_SN"), edge);
snprintf_P(MGC3130_currentGesture, sizeof(MGC3130_currentGesture), PSTR("%sFL_SN"), edge);
break;
case MGC3130_FLICK_NORTH_SOUTH:
//snprintf_P(log, sizeof(log), PSTR("%sFL_NS"), edge);
snprintf_P(MGC3130_currentGesture, sizeof(MGC3130_currentGesture), PSTR("%sFL_NS"), edge);
break;
case MGC3130_CIRCLE_CLOCKWISE:
//snprintf_P(log, sizeof(log), PSTR("CW"));
snprintf_P(MGC3130_currentGesture, sizeof(MGC3130_currentGesture), PSTR("CW"));
break;
case MGC3130_CIRCLE_CCLOCKWISE:
//snprintf_P(log, sizeof(log), PSTR("CCW"));
snprintf_P(MGC3130_currentGesture, sizeof(MGC3130_currentGesture), PSTR("CCW"));
break;
}
//AddLog_P(LOG_LEVEL_DEBUG, log);
}
bool MGC3130_handleTouch(){
//char log[LOGSZ];
bool success = false; // if we find a touch of higher order, we are done
if (MGC_data.out.touchInfo.doubleTapCentre && !success){
//snprintf_P(log, sizeof(log), PSTR("DTAP_CENTRE"));
snprintf_P(MGC3130_currentGesture, sizeof(MGC3130_currentGesture), PSTR("DT_C"));
MGC3130_touchTimeout = 5;
success = true;
MGC3130_touchCounter = 1;
}
else if (MGC_data.out.touchInfo.doubleTapEast && !success){
//snprintf_P(log, sizeof(log), PSTR("DTAP_EAST"));
snprintf_P(MGC3130_currentGesture, sizeof(MGC3130_currentGesture), PSTR("DT_E"));
MGC3130_touchTimeout = 5;
success = true;
MGC3130_touchCounter = 1;
}
else if (MGC_data.out.touchInfo.doubleTapNorth && !success){
//snprintf_P(log, sizeof(log), PSTR("DTAP_NORTH"));
snprintf_P(MGC3130_currentGesture, sizeof(MGC3130_currentGesture), PSTR("DT_N"));
MGC3130_touchTimeout = 5;
success = true;
MGC3130_touchCounter = 1;
}
else if (MGC_data.out.touchInfo.doubleTapWest && !success){
//snprintf_P(log, sizeof(log), PSTR("DTAP_WEST"));
snprintf_P(MGC3130_currentGesture, sizeof(MGC3130_currentGesture), PSTR("DT_W"));
MGC3130_touchTimeout = 5;
success = true;
MGC3130_touchCounter = 1;
}
else if (MGC_data.out.touchInfo.doubleTapSouth && !success){
//snprintf_P(log, sizeof(log), PSTR("DTAP_SOUTH"));
snprintf_P(MGC3130_currentGesture, sizeof(MGC3130_currentGesture), PSTR("DT_S"));
MGC3130_touchTimeout = 5;
success = true;
MGC3130_touchCounter = 1;
}
if (MGC_data.out.touchInfo.tapCentre && !success){
//snprintf_P(log, sizeof(log), PSTR("TAP_CENTRE"));
snprintf_P(MGC3130_currentGesture, sizeof(MGC3130_currentGesture), PSTR("TP_C"));
MGC3130_touchTimeout = 2;
success = true;
MGC3130_touchCounter = 1;
}
else if (MGC_data.out.touchInfo.tapEast && !success){
//snprintf_P(log, sizeof(log), PSTR("TAP_EAST"));
snprintf_P(MGC3130_currentGesture, sizeof(MGC3130_currentGesture), PSTR("TP_E"));
MGC3130_touchTimeout = 2;
success = true;
MGC3130_touchCounter = 1;
}
else if (MGC_data.out.touchInfo.tapNorth && !success){
//snprintf_P(log, sizeof(log), PSTR("TAP_NORTH"));
snprintf_P(MGC3130_currentGesture, sizeof(MGC3130_currentGesture), PSTR("TP_N"));
MGC3130_touchTimeout = 2;
success = true;
MGC3130_touchCounter = 1;
}
else if (MGC_data.out.touchInfo.tapWest && !success){
//snprintf_P(log, sizeof(log), PSTR("TAP_WEST"));
snprintf_P(MGC3130_currentGesture, sizeof(MGC3130_currentGesture), PSTR("TP_W"));
MGC3130_touchTimeout = 2;
success = true;
MGC3130_touchCounter = 1;
}
else if (MGC_data.out.touchInfo.tapSouth && !success){
//snprintf_P(log, sizeof(log), PSTR("TAP_SOUTH"));
snprintf_P(MGC3130_currentGesture, sizeof(MGC3130_currentGesture), PSTR("TP_S"));
MGC3130_touchTimeout = 2;
success = true;
MGC3130_touchCounter = 1;
}
else if (MGC_data.out.touchInfo.touchCentre && !success){
//snprintf_P(log, sizeof(log), PSTR("TOUCH_CENTRE"));
snprintf_P(MGC3130_currentGesture, sizeof(MGC3130_currentGesture), PSTR("TH_C"));
success = true;
MGC3130_touchCounter++; // This will reset to 0 after touching for approx. 1h and 50 minutes ;)
}
else if (MGC_data.out.touchInfo.touchEast && !success){
//snprintf_P(log, sizeof(log), PSTR("TOUCH_EAST"));
snprintf_P(MGC3130_currentGesture, sizeof(MGC3130_currentGesture), PSTR("TH_E"));
success = true;
MGC3130_touchCounter++;
}
else if (MGC_data.out.touchInfo.touchNorth && !success){
//snprintf_P(log, sizeof(log), PSTR("TOUCH_NORTH"));
snprintf_P(MGC3130_currentGesture, sizeof(MGC3130_currentGesture), PSTR("TH_N"));
success = true;
MGC3130_touchCounter++;
}
else if (MGC_data.out.touchInfo.touchWest && !success){
//snprintf_P(log, sizeof(log), PSTR("TOUCH_WEST"));
snprintf_P(MGC3130_currentGesture, sizeof(MGC3130_currentGesture), PSTR("TH_W"));
success = true;
MGC3130_touchCounter++;
}
else if (MGC_data.out.touchInfo.touchSouth && !success){
//snprintf_P(log, sizeof(log), PSTR("TOUCH_SOUTH"));
snprintf_P(MGC3130_currentGesture, sizeof(MGC3130_currentGesture), PSTR("TH_S"));
success = true;
MGC3130_touchCounter++;
}
//AddLog_P(LOG_LEVEL_DEBUG, log);
return success;
}
void MGC3130_handleAirWheel(){
MGC3130_delta = MGC_data.out.airWheel - MGC3130_lastrotation;
MGC3130_lastrotation = MGC_data.out.airWheel;
MGC3130_rotValue = MGC3130_rotValue + MGC3130_delta;
if(MGC3130_rotValue < MGC3130_MIN_ROTVALUE){
MGC3130_rotValue = MGC3130_MIN_ROTVALUE;
}
if(MGC3130_rotValue > MGC3130_MAX_ROTVALUE){
MGC3130_rotValue = MGC3130_MAX_ROTVALUE;
}
}
void MGC3130_handleSystemStatus(){
//Serial.println("Got System status");
}
bool MGC3130_receiveMessage(){
if(MGC3130_readData()){
switch(MGC_data.out.id){
case MGC3130_SENSOR_DATA:
MGC3130_handleSensorData();
break;
case MGC3130_SYSTEM_STATUS:
MGC3130_handleSystemStatus();
break;
case MGC3130_FW_VERSION:
hwRev[0] = MGC_data.fw.hwRev[1];
hwRev[1] = MGC_data.fw.hwRev[0];
loaderVersion[0] = MGC_data.fw.loaderVersion[0];
loaderVersion[1] = MGC_data.fw.loaderVersion[1];
loaderPlatform = MGC_data.fw.loaderPlatform;
snprintf_P(MGC3130_firmwareInfo, sizeof(MGC3130_firmwareInfo), PSTR("FW: %s"), MGC_data.fw.fwVersion);
MGC3130_firmwareInfo[20] = '\0';
// Serial.print(MGC3130_firmwareInfo);
break;
}
return true;
}
return false;
}
bool MGC3130_readData()
{
bool success = false;
if (!digitalRead(MGC3130_xfer)){
pinMode(MGC3130_xfer, OUTPUT);
digitalWrite(MGC3130_xfer, LOW);
Wire.requestFrom(MGC3130_I2C_ADDR, (uint16_t)32); // request usual data output
MGC_data.buffer[0] = 4; // read at least header, but update after first read anyway
unsigned char i = 0;
while(Wire.available() && (i < MGC_data.buffer[0])){
MGC_data.buffer[i] = Wire.read();
i++;
}
digitalWrite(MGC3130_xfer, HIGH);
pinMode(MGC3130_xfer, INPUT);
success = true;
}
return success;
}
void MGC3130_nextMode(){
if (MGC3130_mode < 3){
MGC3130_mode++;
}
else{
MGC3130_mode = 1;
}
switch(MGC3130_mode){ // there is more to be done in the future
case 1:
MGC3130_sendMessage(MGC3130disableAirwheel,16);
break;
case 2:
MGC3130_sendMessage(MGC3130enableAirwheel,16);
break;
case 3:
MGC3130_sendMessage(MGC3130disableAirwheel,16);
break;
}
}
void MGC3130_loop()
{
if(MGC3130_touchTimeout > 0){
MGC3130_touchTimeout--;
}
MGC3130_receiveMessage();
}
bool MGC3130_detect(void)
{
if (MGC3130_type){
return true;
}
pinMode(MGC3130_xfer, INPUT_PULLUP);
pinMode(MGC3130_reset, OUTPUT);
digitalWrite(MGC3130_reset, LOW);
delay(10);
digitalWrite(MGC3130_reset, HIGH);
delay(50);
bool success = false;
success = MGC3130_receiveMessage(); // This should read the firmware info
if (success) {
strcpy_P(MGC3130stype, PSTR("MGC3130"));
AddLog_P2(LOG_LEVEL_DEBUG, S_LOG_I2C_FOUND_AT, MGC3130stype, MGC3130_I2C_ADDR);
MGC3130_currentGesture[0] = '\0';
MGC3130_type = true;
} else {
AddLog_P2(LOG_LEVEL_DEBUG, PSTR("MGC3130 did not respond at address 0x%x"), MGC3130_I2C_ADDR);
}
return success;
}
/*********************************************************************************************\
* Presentation
\*********************************************************************************************/
void MGC3130_show(bool json)
{
if (!MGC3130_type) { return; }
char status_chr[2];
if (MGC_data.out.systemInfo.DSPRunning) {
sprintf (status_chr, "1");
}
else{
sprintf (status_chr, "0");
}
if (json) {
if (MGC3130_mode == 3 && !MGC3130_triggeredByTouch) {
if (MGC_data.out.systemInfo.positionValid && !(MGC_data.out.x == MGC3130_lastSentX && MGC_data.out.y == MGC3130_lastSentY && MGC_data.out.z == MGC3130_lastSentZ)) {
ResponseAppend_P(PSTR(",\"%s\":{\"X\":%u,\"Y\":%u,\"Z\":%u}"),
MGC3130stype, MGC_data.out.x/64, MGC_data.out.y/64, (MGC_data.out.z-(uint16_t)MGC3130_MIN_ZVALUE)/64);
MGC3130_lastSentX = MGC_data.out.x;
MGC3130_lastSentY = MGC_data.out.y;
MGC3130_lastSentZ = MGC_data.out.z;
}
}
MGC3130_triggeredByTouch = false;
if (MGC3130_mode == 2) {
if (MGC_data.out.systemInfo.airWheelValid && (MGC3130_rotValue != MGC3130_lastSentRotValue)) {
ResponseAppend_P(PSTR(",\"%s\":{\"AW\":%i}"), MGC3130stype, MGC3130_rotValue);
MGC3130_lastSentRotValue = MGC3130_rotValue;
}
}
if (MGC3130_currentGesture[0] != '\0') {
if (millis() - MGC3130_touchTimeStamp > 220 ) {
MGC3130_touchCounter = 1;
}
ResponseAppend_P(PSTR(",\"%s\":{\"%s\":%u}"), MGC3130stype, MGC3130_currentGesture, MGC3130_touchCounter);
MGC3130_currentGesture[0] = '\0';
MGC3130_touchTimeStamp = millis();
}
#ifdef USE_WEBSERVER
} else {
WSContentSend_PD(HTTP_MGC_3130_SNS, MGC3130stype, status_chr, hwRev[0], hwRev[1], loaderVersion[0], loaderVersion[1], loaderPlatform );
#endif // USE_WEBSERVER
}
}
/*********************************************************************************************\
* Command Sensor36
*
* Command | Payload | Description
* ---------|---------|--------------------------
* Sensor36 | | ...
* Sensor36 | 0 | Next Mode - cycle through the modes
* Sensor36 | 1 | Gesture Mode
* Sensor36 | 2 | Airwheel Mode
* Sensor36 | 3 | Position Mode with x,y,z - z must be higher than half of the max. sensing height
\*********************************************************************************************/
bool MGC3130CommandSensor()
{
bool serviced = true;
switch (XdrvMailbox.payload) {
case 0: // cycle through the modes
MGC3130_nextMode();
break;
case 1: // gesture & touch
MGC3130_mode = 1;
MGC3130_sendMessage(MGC3130disableAirwheel,16);
break;
case 2: // airwheel & touch
MGC3130_mode = 2;
MGC3130_sendMessage(MGC3130enableAirwheel,16);
break;
case 3: // position & touch
MGC3130_mode = 3;
MGC3130_sendMessage(MGC3130disableAirwheel,16);
break;
}
return serviced;
}
/*********************************************************************************************\
* Interface
\*********************************************************************************************/
bool Xsns36(uint8_t function)
{
bool result = false;
if (i2c_flg) {
if ((FUNC_INIT == function) && (pin[GPIO_MGC3130_XFER] < 99) && (pin[GPIO_MGC3130_RESET] < 99)) {
MGC3130_detect();
}
else if (MGC3130_type) {
switch (function) {
case FUNC_EVERY_50_MSECOND:
MGC3130_loop();
break;
case FUNC_COMMAND_SENSOR:
if (XSNS_36 == XdrvMailbox.index) {
result = MGC3130CommandSensor();
}
break;
case FUNC_JSON_APPEND:
MGC3130_show(1);
break;
#ifdef USE_WEBSERVER
case FUNC_WEB_SENSOR:
MGC3130_show(0);
break;
#endif // USE_WEBSERVER
}
}
}
return result;
}
#endif // USE_MGC3130
#endif // USE_I2C