nrf51822 --TWI(硬件IIC)
1.目的
学习nrf51822硬件IIC通信
2.分析
IIC是常用的通信接口，现在用IIC和MC3413加速度传感器通信来读取加速度值。TWI（Two Wire Interface）
3.平台：
协议栈版本：SDK10.0.0
编译软件：keil 5.14
硬件平台：nrf51822最小系统
例子：SDK 10.0.0\examples\ble_peripheral\ble_app_uart\pca10028\s110\arm4
4.步骤
1.打开\SDK10.0\components\drivers_nrf\twi_master\deprecated目录
把twi_hw_master.c文件加入到工程里面。并设置路径
在twi _hw_master.c 里面添加函数如下：
ii2c_device_wirte_byte(uint8_t address, uint8_t data) : 写某个地址的数据，address为寄存器地址，data是写数据
bool i2c_device_wirte_data(uint8_t address, uint8_t *data,uint8_t lenght) ：往某地地址写数据
uint8_t i2c_device_read_byte(uint8_t address, uint8_t *p_read_byte,uint8_t length);在某个地址开始处读数据。
/*******************************************************************************
* ???? : i2c_device_wirte_byte
* ?? : wang
*
* ? ? : void
* ? ? : void
* ? ? : void
* ???? : 20160317
*******************************************************************************/
bool i2c_device_wirte_byte(uint8_t address, uint8_t data){
uint8_t write_byte[2];
write_byte[0] = address;
write_byte[1] = data;
return twi_master_transfer(i2c_device_address,write_byte,sizeof(write_byte),TWI_ISSUE_STOP);
}
/*******************************************************************************
* ???? : i2c_device_wirte_data
* ?? : wang
*
* ? ? : void
* ? ? : void
* ? ? : void
* ???? : 20160317
*******************************************************************************/
bool i2c_device_wirte_data(uint8_t address, uint8_t *data,uint8_t lenght)
{
return twi_master_transfer(i2c_device_address,data,lenght,TWI_ISSUE_STOP);
}
/*******************************************************************************
* ???? : i2c_device_read_byte
* ?? : wang
*
* ? ? : void
* ? ? : void
* ? ? : void
* ???? : 20160317
*******************************************************************************/
uint8_t i2c_device_read_byte(uint8_t address, uint8_t *p_read_byte,uint8_t length)
{ bool i2c_trans_state = false ;
i2c_trans_state = twi_master_transfer(i2c_device_address,&address,1,TWI_ISSUE_STOP);
while(i2c_trans_state == false);
i2c_trans_state =twi_master_transfer(i2c_device_address | TWI_READ_BIT,p_read_byte,length,TWI_ISSUE_STOP);
while(i2c_trans_state == false);
return i2c_trans_state ;
}
2.在主函数里面添加对应的头文件
3.在#include "twi_master_config.h"中，设置SCL, SDA的管脚，中断脚，以及传感器地址。
/* Copyright (c) 2012 Nordic Semiconductor. All Rights Reserved.
*
* The information contained herein is property of Nordic Semiconductor ASA.
* Terms and conditions of usage are described in detail in NORDIC
* SEMICONDUCTOR STANDARD SOFTWARE LICENSE AGREEMENT.
*
* Licensees are granted free, non-transferable use of the information. NO
* WARRANTY of ANY KIND is provided. This heading must NOT be removed from
* the file.
*
*/
#ifndef TWI_MASTER_CONFIG
#define TWI_MASTER_CONFIG
#define TWI_MASTER_CONFIG_CLOCK_PIN_NUMBER (8)
#define TWI_MASTER_CONFIG_DATA_PIN_NUMBER (9)
#define GSENSOR_INT_PIN_NUMBER (10)
#define I2C_ADR(address) (unsigned char)(address << 1)
#define GSENSOR_I2C_DEVICE_ADDRESS I2C_ADR(0x4c)
#endif
3.在主函数中
仿真测试结果如下：读出器件的ID为0x1B
查看手册，画线的地方。*表示可以是任何值，可见0x1B是正确的、
表示通信成功。。。。。
附件：MC3413手册 http://share.weiyun.com/aec97649305e4e70dc10df94fe02ff49