nRF51x22 I2C Master Driver

1. 最近開始接觸nRF51x22系列的東西, 真的是有點小複雜, 因此就把最近弄好的一些東西先簡
    易備份在Blogger上, 以方便之後有需要的時候容易能馬上使用.

2. 使用I2C Master Driver之前, 必須要先include以下的c & h file, 才能正常使用, 檔名及路徑如
    下:

• 測試的版本皆是在nRF51_SDK_9.0.0_2e23562.zip這個sdk版本下進行測試的.

• twi_hw_master.c:
  \components\drivers_nrf\twi_master\incubated\

• twi_master.h:
  \components\drivers_nrf\twi_master\incubated\

• twi_master_config.h:
  \components\drivers_nrf\twi_master\incubated\config\

3. 接著就是使用底下的i2c.c & i2c.h 這兩個檔案就可以使用了.

i2c.c:
--------------------------------------------------------------------------------------------------------------------------

#include "i2c.h"

void I2C_Master_Init(void)
{
 twi_master_init();
}

int I2C_Write(uint8_t DeviceAddr, uint8_t RegAddr, uint8_t* pBuffer, uint16_t NumByteToWrite)
{
   #define i2c_write_data_len 6
   uint8_t w2_data[i2c_write_data_len+1], i;

   w2_data[0] = RegAddr;
   for ( i = 0 ; i < NumByteToWrite ; i++ ) {
 w2_data[i +1] = pBuffer[i];  
   }

   if(twi_master_transfer(DeviceAddr,w2_data,NumByteToWrite+1,TWI_ISSUE_STOP) == false)
        return -1;

   return 0;
}

int I2C_Read(uint8_t DeviceAddr, uint8_t RegAddr, uint8_t* pBuffer, uint16_t NumByteToRead)
{
 
   if(twi_master_transfer(DeviceAddr, &RegAddr, 1, TWI_DONT_ISSUE_STOP) == false)
 return -1;

   if(twi_master_transfer(DeviceAddr|TWI_READ_BIT, pBuffer, NumByteToRead, TWI_ISSUE_STOP) == false)
 return -1;
  
   return 0; 
}

i2c.h:
--------------------------------------------------------------------------------------------------------------------------

#include "twi_master.h"

void I2C_Master_Init(void);
int I2C_Write(uint8_t DeviceAddr, uint8_t RegAddr, uint8_t* pBuffer, uint16_t NumByteToWrite);
int I2C_Read(uint8_t DeviceAddr, uint8_t RegAddr, uint8_t* pBuffer, uint16_t NumByteToRead);

4. 調整i2c speed的地方在twi_master_init()裡面:

TWI_FREQUENCY_FREQUENCY_K400 = 400KHz
TWI_FREQUENCY_FREQUENCY_K250 = 250KHz
TWI_FREQUENCY_FREQUENCY_K100 = 100KHz

5. 調整i2c gpio pin的地方在twi_master_config.h:

    SCL = 1U = GPIO1.

    SDA = 3U = GPIO3.