NOTICE: 1, the timing for Start, Stop, ACK, NACK, write and read is same as I2C

Transcription

1 DPS01 USER GUIDE

2 DPS01 is a module which integrated digital atmospheric pressure altitude Temperature Compass weather forecast. No external components required It is a complete sensing system with on-chip signal processing and integrated I2C bus, allowing the device to be connected directly to a microprocessor, Features Supply voltage 2.4v-3.6v -20 C to + 70 C operating range Pressure sense:0.1hpa Pressure accuracy:±1.5hpa Pressure range:300hpa~1100hpa Altitude sense: 1m Altitude range:-698m~8948m Temperature sense:0.1 Temperature acuuracy:±0.5 Temperature range:-40 ~+85 Applications Pressure measurement and control systems Mobile altimeter/barometer systems Weather forecast products Adventure or multi-mode watches Electronic Compass GPS Navigation Position Sensing Vehicle Detection Magnetometry

3 NOTICE: 1, the timing for Start, Stop, ACK, NACK, write and read is same as I2C 2, the timing for write is : start + write 0x20 +ACK + write command + ACK + stop 3, the timing for read is : start + write 0x21 + ACK + read data1 + ACK + read data2+ ACK + read datax+ NACK + stop 4, for compass calibration, it will last for around 9.5s, during this period, it won t respond for any command. 5, For any command, if you don t get the ACK from the module, you must add the timeout (0.1s) in your program. And resend this command again till you got the right ACK. 6, When switch the write command to read command you need 200ms and 10ms for switch from read to write. 7, When you want the module to be in power save mode, you need to send the write command (0x71) 8, When wake up from sleep mode, you need to send write command (0x70), 9, For the frequency of I2C, you must be lower than 5KHz. 10,For the power supply it is limited to ( V) 11,For Data reading, the Highest byte is first and MSB in each byte. For example Start + 0x20 + ack + 0xa0 + ack + stop Delay 200ms Start + 0x21 + ack + 0x00 + ack + 0x03 + ack + 0x48+ NACK + stop The altitude got is 0x000348, and it is 84.0m 12, For temperature and altitude, the highest bit will show it is positive or negative. When the highest bit is 1, the value is negative. The other bit show the actual value. For example, for altitude, when the data got is 0x80111c, the actual altitude is : m. 13, For wakeup command, to make sure the wakeup command has been got correct, you d better send this command twice. 14, Too frequent reading of pressure,temperature, altitude, compass will increase the noise of the reading value, suggest you reading the pressure, temperature, altitude once per second or longer, and read the compass once every 0.4S. 15, The pressure sensor is very sensitive to the environment, if you don t want to show this fast changing reading, you can use below method to get the stable pressure reading. First read 8 times of the pressure value continuously, discard the maximum and minimum value, get the average of the rest 6 value, and take the average reading as the final reading. For example, the 8 times of the pressure reading is: , , , , ,

4 Then, discard and , the pressure reading = ( )/6 = , It is the same way as pressure when handle the altitude and temperature. Wake up command: Start + 0x20 + ACK_from _module + 0x70 + ACK_from_module + stop Delay 1s Sleep command Start + 0x20 + ACK_from _module + 0x71 + ACK_from_module + stop Delay 100ms Read altitude command Start + 0x20 + ACK_from _module + 0xa0 + ACK_from_module + stop Delay 200ms Start + 0x21 + ACK_from _module + Data1 + ACK_from_master + Data2 + ACK_from_master + Data3 + NACK_from_master + Stop Delay 10ms Read pressure command Start + 0x20 + ACK_from _module + 0xb0 + ACK_from_module + stop Delay 200ms Start + 0x21 + ACK_from _module + Data1 + ACK_from_master + Data2 + ACK_from_master + Data3 + NACK_from_master + Stop Delay 10ms Read weather forecast command Start + 0x20 + ACK_from _module + 0xb3 + ACK_from_module + stop Delay 200ms Start + 0x21 + ACK_from _module + Data1 + NACK_from_master + Stop Delay 10ms Read Compass command Start + 0x20 + ACK_from _module + 0xc0 + ACK_from_module + stop Delay 200ms Start + 0x21 + ACK_from _module + Data1 + ACK_from_master + Data2 + NACK_from_master + Stop Delay 10ms

5 Read Temperature command Start + 0x20 + ACK_from _module + 0x80 + ACK_from_module + stop Delay 200ms Start + 0x21 + ACK_from _module + Data1 + ACK_from_master + Data2 + NACK_from_master + Stop Delay 10ms Start Compass calibration command Start + 0x20 + ACK_from _module + 0xE0 + ACK_from_module + stop

6 DEMO PROGRAME #include<pic.h> #include<math.h> #define COMMUNI_SUCCEED 1 #define COMMUNI_FAILED 0 #define noack 0 #define ACK 1 #define PRESSURE_MODE 0 #define Temperature_MODE 1 #define ALTITUDE_MODE 2 #define COMPASS_MODE 3 #define WEATHER_MODE 4 #define POWER_OFF_MODE 5 #define MODE_KEY 0x1e// RA0 #define START_COMPASS_CALIBRATION_KEY 0x1d // RA1 #define EXIT_COMPASS_CALIBRATION_KEY 0x1b // RA2 #define POWER_ON_KEY 0x17 //RA3 #define POWER_OFF_KEY 0x0f //RA4 #define POWER_ON 0 #define POWER_OFF 1 #define COMPASS_CALIBRATION_COMMAND 0xe0 #define EXIT_COMPASS_CALIBRATION_COMMAND 0xe1 #define PRESS_WRITE_COMMAND 0xB0 #define TEMPERATURE_WRITE_COMMAND 0x80 #define ALTITUDE_WRITE_COMMAND 0xA0 #define COMPASS_WRITE_COMMAND 0xC0 #define WEATHER_WRITE_COMMAND 0xB3 #define MODULE_WAKEUP_WRITE_COMMAND 0X70 #define MODULE_SLEEP_WRITE_COMMAND 0X71

7 #define LED_A RD0 #define LED_B RD1 #define LED_C RD2 #define LED_D RD3 #define LED_E RD4 #define LED_F RD5 #define LED_G RD6 #define LED_DP RD7 #define LED_1 RB0 //RB0 //RA0 #define LED_2 RB1 //RB1 //RA1 #define LED_3 RB2 //RB2 #define LED_4 RB3 //RB3 //RA3 #define LED_5 RB4 //RB4 #define LED_6 RB5 //RB5 //RA3 #define SCK RC0 #define DATA RC1 #define DATA_SET TRISC1 #define DATA_INPUT 1 #define DATA_OUTPUT 0 #define DELAY100US 10 #define LED_ON 1 #define LED_OFF 0 #define LED_PEDO RC2 #define LED_TEMPERATURE RC3 #define LED_PRESSURE RC4 #define LED_ALTIDUTE RC5 #define LED_COMPASS RC6 #define LED_WEATHER RC7 // a b const unsigned char Tab_DispCoed[12]=0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,0xff,0xbf; unsigned char DispData1; unsigned char DispData2; unsigned char DispData3; unsigned char DispData4; unsigned char DispData5; unsigned char DispData6;

8 unsigned char DispCount; unsigned char key; unsigned char mode; unsigned char press_h, press_m, press_l; unsigned char altitude_h, altitude_m, altitude_l; unsigned char weather; unsigned char compass_h, compass_l; unsigned char temperature_h, temperature_l; unsigned char communicate_status; unsigned long int cal_temp_ram; typedef struct unsigned char reach_1s : 1; unsigned char reach_5hz : 1; unsigned char temp_is_positive : 1; unsigned char is_disp_press : 1; unsigned char is_disp_altitude : 1; unsigned char is_disp_compass : 1; unsigned char is_disp_pedo : 1; unsigned char is_disp_temp : 1; unsigned char is_disp_weather : 1; FlagType; FlagType Flag; void port_init(void); void timer2_init(void);

9 void IIC_SCL_HIGH(void); void IIC_SCL_LOW(void); void IIC_Start(void); void IIC_Stop(void); void IIC_ACK(void); void IIC_NoAck(void); unsigned char IIC_ReadByte(void); unsigned char IIC_WriteByte( unsigned char ucdata ); void SysDelay1ms(unsigned int x); void SysDelay(unsigned int t); unsigned char key_scan_main_program(void); void pressure_led_display(void); void temperature_led_display(void); void altitude_led_display(void); void compass_led_display(void); void weather_led_display(void); void poweroff_led_display(void); void send_dps01_write_command(unsigned char command); void send_read_press_command(void); void send_read_altitude_command(void); void send_read_compass_command(void); void send_read_weather_command(void); void display_press(void); void display_altitude(void); void display_temperature(void); void display_compass(void); void display_weather(void); void key_handle_program(void); void mode_handle_program(void); void send_read_temperature_command(void); void display_compass_calibrate(void); void display_power_off(void); void main() OSCCON = 0X70; // 8M crystal WDTCON = 0X00;

10 DispCount = 2; SysDelay1ms(1000); timer2_init(); // port_init(); INTCON = 0xc0; // enable interrupt, 5MS 中断, 用于显示 DispData1 = 0x01; DispData2 = 0x02; DispData3 = 3; DispData4 = 4; DispData5 = 5; DispData6 = 6; send_dps01_write_command(module_wakeup_write_command); while( communicate_status!= COMMUNI_SUCCEED) send_dps01_write_command(module_wakeup_write_command); SysDelay1ms(1000); mode = PRESSURE_MODE; while(1) key = key_scan_main_program(); key_handle_program(); mode_handle_program(); unsigned char key_scan_main_program(void) unsigned char i,j; i = PORTA; i &= 0x1f; // only RA0 --RA4, normal high if ( i!= 0x1f) SysDelay1ms(30);

11 j = PORTA; j &= 0x1f; if(i == j) SysDelay1ms(100); return (i); // key pressed else return(0); else return(0); void timer2_init(void) T2CON = 0x7f; // timer2 on and 16 pre, postscale PR2 = 15;//156; // 50hZ*4, 4m/4/16/16/50 = 5ms TMR2IE = 1; NOP(); void interrupt ISR_timer(void) unsigned char i; if(tmr2if) switch(dispcount) case 2:

12 PORTD = Tab_DispCoed[DispData1]; LED_1 = LED_ON ; LED_2 = LED_OFF; LED_3 = LED_OFF; LED_4 = LED_OFF; LED_5 = LED_OFF; LED_6 = LED_OFF; break; DispCount <<= 1; case 4: PORTD = Tab_DispCoed[DispData2]; LED_1 = LED_OFF ; LED_2 = LED_ON; LED_3 = LED_OFF; LED_4 = LED_OFF; LED_5 = LED_OFF; LED_6 = LED_OFF; break; DispCount <<= 1; case 8: PORTD = Tab_DispCoed[DispData3]; LED_1 = LED_OFF ; LED_2 = LED_OFF; LED_3 = LED_ON; LED_4 = LED_OFF; LED_5 = LED_OFF; LED_6 = LED_OFF; break; DispCount <<= 1; case 16: PORTD = Tab_DispCoed[DispData4]; if(flag.is_disp_press) PORTD &= 0x7f; // display dot LED_1 = LED_OFF ;

13 LED_2 = LED_OFF; LED_3 = LED_OFF; LED_4 = LED_ON; LED_5 = LED_OFF; LED_6 = LED_OFF; DispCount <<= 1; break; case 32: PORTD = Tab_DispCoed[DispData5]; if((flag.is_disp_temp) (Flag.is_disp_altitude)) PORTD &= 0x7f; // display dot LED_1 = LED_OFF ; LED_2 = LED_OFF; LED_3 = LED_OFF; LED_4 = LED_OFF; LED_5 = LED_ON; LED_6 = LED_OFF; DispCount <<= 1; break; case 64: PORTD = Tab_DispCoed[DispData6]; LED_1 = LED_OFF ; LED_2 = LED_OFF; LED_3 = LED_OFF; LED_4 = LED_OFF; LED_5 = LED_OFF; LED_6 = LED_ON; DispCount = 2; break; TMR2IF=0; void port_init(void) ANSELA = 0; ANSELB = 0;

14 ANSELD = 0; ANSELE = 0; TRISA = 0xFF; // RA PORT IS INPUT ( KEY + OSC) TRISB = 0x00; // rb IS OUTPTU TRISC = 0X00; // PORT C IS OUTPUT TRISD = 0X0; // PORT D IS OUTPUT TRISE = 0x00; // PORTE is output PORTB = PORTC = PORTD= PORTE = 0xff; // all port is high //================================================ void SysDelay(unsigned int t) t *= 2; for(;t>0;t--) #asm NOP NOP NOP NOP NOP NOP NOP #endasm //================================================ void SysDelay1ms(unsigned int x) unsigned char i; x *= 2; for (; x>0; x--) for(i = 200; i>1; i--)

15 NOP(); void pressure_led_display(void) LED_PRESSURE = 1; LED_ALTIDUTE = 0; LED_TEMPERATURE = 0; LED_COMPASS = 0; LED_WEATHER = 0; LED_PEDO = 0; void temperature_led_display(void) LED_PRESSURE = 0; LED_ALTIDUTE = 0; LED_TEMPERATURE = 1; LED_COMPASS = 0; LED_WEATHER = 0; LED_PEDO = 0; void altitude_led_display(void) LED_PRESSURE = 0; LED_ALTIDUTE = 1; LED_TEMPERATURE = 0; LED_COMPASS = 0; LED_WEATHER = 0; LED_PEDO = 0; void compass_led_display(void) LED_PRESSURE = 0; LED_ALTIDUTE = 0; LED_TEMPERATURE = 0; LED_COMPASS = 1; LED_WEATHER = 0;

16 LED_PEDO = 0; void weather_led_display(void) LED_PRESSURE = 0; LED_ALTIDUTE = 0; LED_TEMPERATURE = 0; LED_COMPASS = 0; LED_WEATHER = 1; LED_PEDO = 0; void poweroff_led_display(void) LED_PRESSURE = 0; LED_ALTIDUTE = 0; LED_TEMPERATURE = 0; LED_COMPASS = 0; LED_WEATHER = 0; LED_PEDO = 0; void key_handle_program(void) switch(key) case MODE_KEY: if(mode == POWER_OFF_MODE) mode = 0; else mode ++; if(mode == 0x05) mode = 0; break; case POWER_ON_KEY:

17 mode = PRESSURE_MODE; send_dps01_write_command(module_wakeup_write_command); while( communicate_status!= COMMUNI_SUCCEED) send_dps01_write_command(module_wakeup_write_command); SysDelay1ms(200); break; case POWER_OFF_KEY: mode = POWER_OFF_MODE; display_power_off(); poweroff_led_display(); send_dps01_write_command(module_sleep_write_command); while( communicate_status!= COMMUNI_SUCCEED) send_dps01_write_command(module_sleep_write_command); SysDelay1ms(200); break; case START_COMPASS_CALIBRATION_KEY: display_compass_calibrate(); mode = COMPASS_MODE; send_dps01_write_command(compass_calibration_command); while( communicate_status!= COMMUNI_SUCCEED) send_dps01_write_command(compass_calibration_command); break; case EXIT_COMPASS_CALIBRATION_KEY: mode = COMPASS_MODE; send_dps01_write_command(exit_compass_calibration_command);

18 while( communicate_status!= COMMUNI_SUCCEED) send_dps01_write_command(exit_compass_calibration_command); break; void mode_handle_program(void) if(mode == PRESSURE_MODE) pressure_led_display(); send_dps01_write_command(press_write_command); while( communicate_status!= COMMUNI_SUCCEED) send_dps01_write_command(press_write_command); SysDelay1ms(200); send_read_press_command(); display_press(); SysDelay1ms(10); else if(mode == Temperature_MODE) temperature_led_display(); send_dps01_write_command(temperature_write_command); while( communicate_status!= COMMUNI_SUCCEED) send_dps01_write_command(temperature_write_command); SysDelay1ms(200); send_read_temperature_command(); display_temperature(); SysDelay1ms(10); else if(mode == ALTITUDE_MODE)

19 altitude_led_display(); send_dps01_write_command(altitude_write_command); while( communicate_status!= COMMUNI_SUCCEED) send_dps01_write_command(altitude_write_command); SysDelay1ms(200); send_read_altitude_command(); display_altitude(); SysDelay1ms(10); else if(mode == COMPASS_MODE) compass_led_display(); send_dps01_write_command(compass_write_command); while( communicate_status!= COMMUNI_SUCCEED) send_dps01_write_command(compass_write_command); SysDelay1ms(100); send_read_compass_command(); display_compass(); SysDelay1ms(10); else if(mode == WEATHER_MODE) weather_led_display(); send_dps01_write_command(weather_write_command); while( communicate_status!= COMMUNI_SUCCEED) send_dps01_write_command(weather_write_command); SysDelay1ms(200); send_read_weather_command(); display_weather(); SysDelay1ms(10); void display_press(void)

20 unsigned long int j; Flag.is_disp_press = 1; Flag.is_disp_altitude = 0; Flag.is_disp_compass = 0; Flag.is_disp_pedo = 0; Flag.is_disp_temp = 0; Flag.is_disp_weather = 0; NOP(); cal_temp_ram = press_h; cal_temp_ram *= 256; cal_temp_ram *= 256; cal_temp_ram += (unsigned int)(press_m <<8); cal_temp_ram += press_l; DispData6 = cal_temp_ram%10; j= cal_temp_ram/10; DispData5 = j%10; j= cal_temp_ram/100; DispData4 = j%10; j= cal_temp_ram/1000; DispData3 = j%10; j= cal_temp_ram/10000; DispData2 = j%10; j= cal_temp_ram/100000; DispData1 = j%10; if(dispdata1 ==0) DispData1 = 0x0a; if( DispData2 ==0) DispData2 = 0x0a;

21 void display_altitude(void) unsigned long int i, j; Flag.is_disp_press = 0; Flag.is_disp_altitude = 1; Flag.is_disp_compass = 0; Flag.is_disp_pedo = 0; Flag.is_disp_temp = 0; Flag.is_disp_weather = 0; if((altitude_h &0x80) ==0x80) DispData1= 0x0b ; // display - altitude is negative altitude_h &= 0x7f; else DispData1= 0x0a ; i = altitude_h; i <<= 8; i <<= 8; i += (unsigned int)(altitude_m <<8); i += altitude_l; DispData6 = i%10; j= i/10; DispData5 = j%10; j= i/100; DispData4 = j%10; j= i/1000; DispData3 = j%10; j= i/10000; DispData2 = j%10;

22 if( DispData2 ==0) DispData2 = 0x0a; if( DispData3 ==0 ) DispData3 = 0x0a; if(dispdata4 == 0x0) DispData4 = 0x0a; void display_temperature(void) unsigned int i, j; Flag.is_disp_press = 0; Flag.is_disp_altitude = 0; Flag.is_disp_compass = 0; Flag.is_disp_pedo = 0; Flag.is_disp_temp = 1; Flag.is_disp_weather = 0; if((temperature_h &0x80) ==0x80) DispData1= 0x0b ; // display -,temperature is negative temperature_h &= 0x7f; else DispData1= 0x0a ; i =(unsigned int)( temperature_h<<8); i += temperature_l; DispData6 = i%10; j= i/10; DispData5 = j%10; j= i/100;

23 DispData4 = j%10; j= i/1000; DispData3 = j%10; j= i/10000; DispData2 = j%10; if( DispData2 ==0) DispData2 = 0x0a; if( DispData3 ==0 ) DispData3 = 0x0a; if(dispdata4 == 0x0) DispData4 = 0x0a; void display_compass(void) unsigned int i, j; Flag.is_disp_press = 0; Flag.is_disp_altitude = 0; Flag.is_disp_compass = 1; Flag.is_disp_pedo = 0; Flag.is_disp_temp = 0; Flag.is_disp_weather = 0; i = (unsigned int)(compass_h<<8); i += compass_l; DispData6 = i%10; j= i/10; DispData5 = j%10; j= i/100; DispData4 = j%10; DispData1 = 0x0a;

24 DispData2 = 0x0a; DispData3 = 0x0a; void display_power_off(void) Flag.is_disp_press = 0; Flag.is_disp_altitude = 0; Flag.is_disp_compass = 0; Flag.is_disp_pedo = 0; Flag.is_disp_temp = 0; Flag.is_disp_weather = 0; DispData6 = 0x0a; DispData5 = 0x0a; DispData4 = 0x0a; DispData1 = 0x0a; DispData2 = 0x0a; DispData3 = 0x0a; void display_compass_calibrate(void) Flag.is_disp_press = 0; Flag.is_disp_altitude = 0; Flag.is_disp_compass = 1; Flag.is_disp_pedo = 0; Flag.is_disp_temp = 0; Flag.is_disp_weather = 0; DispData6 = 0x0b; DispData5 = 0x0b; DispData4 = 0x0b; DispData1 = 0x0a; DispData2 = 0x0a; DispData3 = 0x0a;

25 void display_weather(void) Flag.is_disp_press = 0; Flag.is_disp_altitude = 0; Flag.is_disp_compass = 0; Flag.is_disp_pedo = 0; Flag.is_disp_temp = 0; Flag.is_disp_weather = 1; DispData1 = 0x0a; DispData2 = 0x0a; DispData3 = 0x0a; DispData4 = 0x0a; DispData5 = 0x0a; DispData6 = weather; void send_dps01_write_command(unsigned char command) IIC_Start(); communicate_status = IIC_WriteByte(0x20); if( communicate_status == COMMUNI_SUCCEED) communicate_status = IIC_WriteByte(command); if( communicate_status == COMMUNI_SUCCEED) IIC_Stop(); void send_read_press_command(void) IIC_Start(); communicate_status = IIC_WriteByte(0x21); if( communicate_status == COMMUNI_SUCCEED)

26 press_h = IIC_ReadByte(); IIC_ACK(); press_m = IIC_ReadByte(); IIC_ACK(); press_l = IIC_ReadByte(); IIC_NoAck(); IIC_Stop(); void send_read_temperature_command(void) IIC_Start(); communicate_status = IIC_WriteByte(0x21); if( communicate_status == COMMUNI_SUCCEED) temperature_h = IIC_ReadByte(); IIC_ACK(); temperature_l = IIC_ReadByte(); IIC_NoAck(); IIC_Stop(); void send_read_altitude_command(void) IIC_Start(); communicate_status = IIC_WriteByte(0x21); if( communicate_status == COMMUNI_SUCCEED) altitude_h = IIC_ReadByte(); IIC_ACK(); altitude_m = IIC_ReadByte(); IIC_ACK(); altitude_l = IIC_ReadByte(); IIC_NoAck(); IIC_Stop();

27 void send_read_compass_command(void) IIC_Start(); communicate_status = IIC_WriteByte(0x21); if( communicate_status == COMMUNI_SUCCEED) compass_h = IIC_ReadByte(); IIC_ACK(); compass_l = IIC_ReadByte(); IIC_NoAck(); IIC_Stop(); void send_read_weather_command(void) IIC_Start(); communicate_status = IIC_WriteByte(0x21); if( communicate_status == COMMUNI_SUCCEED) weather = IIC_ReadByte(); IIC_NoAck(); IIC_Stop(); //================================================ void IIC_SCL_HIGH(void) SCK=1; //================================================ void IIC_SCL_LOW(void) SCK=0;

28 void IIC_Start(void) DATA_SET = DATA_OUTPUT; DATA=1; IIC_SCL_HIGH(); DATA=0; IIC_SCL_LOW(); //================================================ void IIC_Stop(void) DATA_SET = DATA_OUTPUT; IIC_SCL_LOW(); DATA=0; IIC_SCL_HIGH(); DATA=1; //================================================ void IIC_ACK(void) DATA_SET = DATA_OUTPUT; DATA=0; IIC_SCL_HIGH();

29 IIC_SCL_LOW(); //================================================ void IIC_NoAck(void) DATA_SET = DATA_OUTPUT; DATA=1; IIC_SCL_HIGH(); IIC_SCL_LOW(); //================================================ unsigned char IIC_ReadByte(void) unsigned char ucvalue; unsigned char ucindex; ucvalue = 0; DATA_SET = DATA_INPUT; for ( ucindex = 0; ucindex < 8; ucindex++ ) ucvalue <<= 1; IIC_SCL_LOW();

30 IIC_SCL_HIGH(); if(data) ucvalue = 1; IIC_SCL_LOW(); return ucvalue; //================================================ unsigned char IIC_WriteByte( unsigned char ucdata ) unsigned char i; DATA_SET = DATA_OUTPUT; for( i = 0; i < 8; i++ ) IIC_SCL_LOW(); if((ucdata & 0x80) == 0x80) DATA=1; else DATA=0; IIC_SCL_HIGH(); ucdata <<= 1; IIC_SCL_LOW();

31 DATA_SET = DATA_INPUT; IIC_SCL_LOW(); IIC_SCL_HIGH(); if( DATA!= 0) IIC_SCL_LOW(); SysDelay1ms(10); return(communi_failed); else IIC_SCL_LOW(); return(communi_succeed); // end