I2C

1 功能概述

I2C 接口可以通过数据引脚 (SDA) 和时钟引脚 (SCL) 连接到 I2C或 SMBus总线。SDA 线和 SCL 线均设置为漏极开漏 (open-drain) 输出，并接上拉电阻 (pull-up resistor)。因此，I2C 和 SMBus 总线上可以挂载多个器件。I2C 接口的每次传输都是由主器件 (Master) 发起和控制，
本章主要介绍通过I2C接口完成对EEPROM芯片的数据读写。目前，cp侧不允许使用I2C，ap侧支持使用I2C0和I2C1。
I2C相关的理论介绍参考: I2C的驱动

备注

1.cp侧不允许使用I2C0和I2C1；
2.ap侧支持使用I2C0和I2C1;

2 代码路径

demo路径：

components\bk_cli\cli_i2c.c

驱动源码路径：

ap\middleware\driver\i2c\i2c_driver.c

ap\middleware\driver\i2c\sim_i2c_driver_v2.c

I2C相关的api介绍参考: I2C的api介绍

备注

1.i2c_driver.c :硬件有中断实现代码
- 2.sim_i2c_driver_v2.c:纯软件实现代码

3 cli命令简介

demo运行依赖的宏配置：

NAME

Description

File

value

CONFIG_I2C

support i2c

ap\middleware\soc\bk7258\bk7258.defconfig

y

CONFIG_I2C_SUPPORT_ID_BITS

support i2c0 or i2c1

ap\middleware\soc\bk7258\bk7258.defconfig

1

CONFIG_SIM_I2C

value y:support software； n: hardware i2c

ap\middleware\soc\bk7258\bk7258.defconfig

n

CONFIG_SIM_I2C_HW_BOARD_V3

support Touch Screen with i2c

ap\middleware\soc\bk7258\bk7258.defconfig

y

demo支持的命令如下表：

Command

Param

Description

i2c_driver init

none

init I2C driver control memory

i2c_driver deinit

none

free all resource related to I2C

i2c {id} init

i2c id number

power up and start the I2C id

i2c {id} deinit

i2c id number

power down and Stop the I2C id

i2c {id} memory_write {data_size} {dev_addr} {mem_addr_size}

id: i2c id number

write data_size bytes of data to the slave device with address dev_id

data_size:size of data written

dev_addr: slave device address

mem_addr_size: size of memory_addr

i2c {id} memory_read {data_size} {dev_addr} {mem_addr_size}

id: i2c id

read data_size bytes of data from slave device

data_size:size of data read

dev_addr: slave device address

mem_addr_size: size of memory_addr

4 I2C PIN脚描述

I2C0对应有1组PIN脚，对应的硬件管脚如下：

I2C0功能

组0

I2C0_CLK

GPIO0

I2C0_SDA

GPIO1

I2C1对应有1组PIN脚，对应的硬件管脚如下：

I2C1功能

组0

I2C1_CLK

GPIO20

I2C1_SDA

GPIO21

4 演示介绍

demo1执行的步骤如下：

1、准备好EEPROM的模块，型号为ZD24C128A，使用I2C1连接方式如下：

2、顺序发送以下命令

cpu1 i2c 1 init

[11:45:42.140]发→◇cpu1 i2c 1 init
[11:45:42.145]收←◆cpu1 i2c 1 init
os:I(6720):create shell_handle, tcb=28078db0, stack=[28077188-28078d88:7168], prio=5
$
$cpu1:i2c:I(6178):I2C(1) init ok, baud_rate:400000
cpu1:cli:I(6178):i2c(1) init

cpu1 i2c 1 memory_write 8 50 1//向EEPROM中写入8字节数据

[11:45:43.027]发→◇cpu1 i2c 1 memory_write 8 50 1
[11:45:43.034]收←◆cpu1 i2c 1 memory_write 8 50 1
os:I(7608):create shell_handle, tcb=28078db0, stack=[28077188-28078d88:7168], prio=5
$
$cpu1:cli:I(7066):i2c(1) memory_write buf_len:8

cpu1 i2c 1 memory_read 8 50 1 //从EEPROM中读取8字节数据

[11:45:44.825]发→◇cpu1 i2c 1 memory_read 8 50 1
[11:45:44.831]收←◆cpu1 i2c 1 memory_read 8 50 1
os:I(9406):create shell_handle, tcb=28078db0, stack=[28077188-28078d88:7168], prio=5
$
$cpu1:cli:I(8864):i2c_read_buf[0]=1
cpu1:cli:I(8864):i2c_read_buf[1]=2
cpu1:cli:I(8864):i2c_read_buf[2]=3
cpu1:cli:I(8864):i2c_read_buf[3]=4
cpu1:cli:I(8864):i2c_read_buf[4]=5
cpu1:cli:I(8864):i2c_read_buf[5]=6
cpu1:cli:I(8864):i2c_read_buf[6]=7
cpu1:cli:I(8864):i2c_read_buf[7]=8
cpu1:cli:I(8864):i2c(1) memory_read buf_len:8

3、时序图

写时序图

i2c_Sequence_ZD24C128A — Figure 2. i2c_wr_Sequence_ZD24C128A

读时序图

demo2执行的步骤如下：

1、准备好EEPROM的模块，型号为FM24C04B，使用I2C1连接方式如下：

2、顺序发送以下命令

cpu1 i2c 1 init

[16:44:55.619]发→◇cpu1 i2c 1 init
[16:44:55.622]收←◆cpu1 i2c 1 init
os:I(3120):create shell_handle, tcb=28078db0, stack=[28077188-28078d88:7168], prio=5
$
$cpu1:i2c:I(2984):I2C(1) init ok, baud_rate:400000
cpu1:cli:I(2984):i2c(1) init

cpu1 i2c 1 memory_write 8 50 0//向EEPROM中写入8字节数据

[16:44:58.285]发→◇cpu1 i2c 1 memory_write 8 50 0
[16:44:58.292]收←◆cpu1 i2c 1 memory_write 8 50 0
os:I(5788):create shell_handle, tcb=28078db0, stack=[28077188-28078d88:7168], prio=5
$
$cpu1:cli:I(5652):i2c(1) memory_write buf_len:8

cpu1 i2c 1 memory_read 8 50 0 //从EEPROM中读取8字节数据

[16:44:59.919]发→◇cpu1 i2c 1 memory_read 8 50 0
[16:44:59.926]收←◆cpu1 i2c 1 memory_read 8 50 0
os:I(7422):create shell_handle, tcb=28078db0, stack=[28077188-28078d88:7168], prio=5
$
$cpu1:cli:I(7286):i2c_read_buf[0]=1
cpu1:cli:I(7286):i2c_read_buf[1]=2
cpu1:cli:I(7286):i2c_read_buf[2]=3
cpu1:cli:I(7286):i2c_read_buf[3]=4
cpu1:cli:I(7286):i2c_read_buf[4]=5
cpu1:cli:I(7286):i2c_read_buf[5]=6
cpu1:cli:I(7286):i2c_read_buf[6]=7
cpu1:cli:I(7286):i2c_read_buf[7]=8
cpu1:cli:I(7286):i2c(1) memory_read buf_len:8

3、时序图

写时序图

i2c_Sequence_FM24C04B — Figure 5. i2c_wr_Sequence_FM24C04B

读时序图

备注

注意：memory_write命令中的dev_addr 50为16进制，因为i2c驱动中会将dev_addr左移一位，所以传入的dev_addr需要将ZD24C128A的dev_addr（1010b）右移一位。