/**********************************************************************
*   Copyright: (C)2023 LingYun IoT System Studio
*      Author: GuoWenxue<guowenxue@gmail.com> QQ: 281143292
* Description: ISKBoard SHT20 R&H sensor Hardware Abstract Layer driver
*
*   ChangeLog:
*        Version    Date       Author            Description
*        V1.0.0  2023.04.3    GuoWenxue      Release initial version
***********************************************************************/

#include <sht20.h>
#include <stdio.h>
#include <string.h>

#define delay_ms(x)		HAL_Delay(x)

enum
{
	TRIG_T_MEASUREMENT_HM    = 0xE3, // command trig. temp meas. hold master
	TRIG_RH_MEASUREMENT_HM   = 0xE5, // command trig. humidity meas. hold master
	TRIG_T_MEASUREMENT_POLL  = 0xF3, // command trig. temp meas. no hold master
	TRIG_RH_MEASUREMENT_POLL = 0xF5, // command trig. humidity meas. no hold master
	USER_REG_W               = 0xE6, // command writing user register
	USER_REG_R               = 0xE7, // command reading user register
	SOFT_RESET               = 0xFE  // command soft reset
};


//#define CONFIG_SHT2X_DEBUG

#ifdef CONFIG_SHT2X_DEBUG
static inline void dump_buf(uint8_t *buf, uint32_t size)
{
	int      i;
	
	if(!buf)
		return ;
	
	for(i=0; i<size; i++)
		printf("%02x ", buf[i]);
	
	printf("\r\n");
}
#endif

#ifdef CONFIG_SHT2X_DEBUG
#define sht2x_print(format,args...) printf(format, ##args)
#else
#define sht2x_print(format,args...) do{} while(0);
#endif
	
	
static int sht2x_measure_value(uint8_t command, uint16_t *val);
static int sht2x_softreset(void);


uint32_t sht20_sample_TrH(uint32_t *temperature, uint32_t *humdity)
{
	uint16_t       sT;
	uint16_t       sRH;
	uint32_t       T;
	uint32_t       RH;
	uint32_t       TRH=TRH_FAIL_VAL;

	i2c_term(SHT2X_I2CBUS);

	if( i2c_init(SHT2X_I2CBUS, SHT2X_CHIPADDR) )
	{
		sht2x_print("SHT20 initial I2C bus failed.\r\n");
		return TRH;
	}

	if( sht2x_softreset() )
	{
		sht2x_print("SHT20 soft reset failed.\r\n");
		goto OUT;
	}

	sht2x_print("Start to measurement temperature...\r\n");
	if( sht2x_measure_value(TRIG_T_MEASUREMENT_POLL, &sT) < 0 )
	{
		sht2x_print("I2C measurement failed\r\n");
		goto OUT;
	}
  
	T=(uint32_t)(100*(float)((175.72*sT)/65536-46.85));
	sht2x_print("Measure temperature: %lu.%lu\r\n", T/100, T%100);
	if( temperature )
		*temperature=T;

	TRH = ((T/100)<<8|(T%100))<<16 | 0xFFFF;
  
	sht2x_print("Start to measurement relative humidity...\r\n");
	if( sht2x_measure_value(TRIG_RH_MEASUREMENT_POLL, &sRH) < 0 )
	{
		goto OUT;
	}

	RH=(uint32_t)(100*(float)((125*sRH)/65535-6.0));
	sht2x_print("Measure relative humidity: %lu.%lu%%\r\n", RH/100, RH%100);
	if( humdity )
		*humdity=RH;
	
	TRH &=  0xFFFF0000 | ((uint16_t)RH/100)<<8 | ((uint16_t)RH%100) ;

OUT:  
	i2c_term(SHT2X_I2CBUS);
	return TRH;
}

int sht2x_softreset(void)
{
	uint8_t           command = SOFT_RESET;
	int               rv = 0;
	
	sht2x_print("Start soft reset sht2x\r\n");
	rv=i2c_write(SHT2X_I2CBUS, &command, 1);
	
	if( rv )
	{
		sht2x_print("SHT2X send soft reset command 0x%0x failure: rv=0x%02x\r\n", command, rv);
		return -rv;
	}
	
	delay_ms(15);
	return 0;
}

static int sht2x_checkcrc(uint8_t *data, uint8_t bytes, uint8_t checksum)
{
  uint8_t crc = 0;	
  uint8_t i;
  uint8_t bit;
  
  //calculates 8-Bit checksum with given polynomial
  for (i=0; i<bytes; ++i)
  { 
    crc ^= (data[i]);
    for (bit=8; bit>0; --bit)
    { 
      if (crc & 0x80) 
        crc = (crc << 1) ^ 0x0131; //POLYNOMIAL;
      else 
        crc = (crc << 1);
    }
  }

  if (crc != checksum)
  {
    return -1;
  }
  else 
  {
    return 0;
  }
}

static int sht2x_measure_value(uint8_t command, uint16_t *val)
{
	uint8_t        buf[3];    /* I2C������buffer */
	int            count=4;    /* �ܹ����Ĵ��� */
  
	if( !val )
	{
		sht2x_print("SHT2X invalid input arguments\r\n");
		return -1;
	}
	
	if(TRIG_T_MEASUREMENT_POLL!=command && TRIG_RH_MEASUREMENT_POLL !=command )
	{
		sht2x_print("SHT2X unsupport command: 0x%0x\r\n", command);
		return -2;
	}

	if( NO_ERROR != i2c_write(SHT2X_I2CBUS, &command, 1) )
	{
		sht2x_print("SHT2X send measure command 0x%0x failure\r\n", command);
		return -3;
	}
  
	if(TRIG_T_MEASUREMENT_POLL == command)
		delay_ms(85);
	else
		delay_ms(29);

	while(count--)
	{
		memset(buf, 0, 3);

		if( !i2c_read(SHT2X_I2CBUS, buf, 3) )
		{
			break;
		}
		delay_ms(5);
	}

	if( sht2x_checkcrc(buf, 2, buf[2])< 0 )
	{
#ifdef CONFIG_SHT2X_DEBUG		
		sht2x_print("Measurement data checksum failure:\r\n");
		dump_buf(buf, 3);
#endif
		return -4;
	}

	if(TRIG_T_MEASUREMENT_POLL == command)
		*val = buf[0]<<8|(buf[1]&0xFC); //14bits(1111 1100)
	else
		*val = buf[0]<<8|(buf[1]&0xFF); //12bits(1100 0000)

	sht2x_print("Measurement temperature value: 0x%04x\r\n", *val);
  
  return 0;
}