51单片机i2c总线读写 *** 作问题

因为开始读取完或者写完一组数据需要一个开始信号和一个终止信号，而这个信号就是数据线的上升下降沿。而后面数据线拉高的原因是为了能正确读取到数据，因为单片机如果是低电平外部器件很有可能不能拉高而一直读到低。手机纯打，往采纳。

什么是单个数据？IIC总线就是把所需的数据经sda数据线串行传入芯片中，需要多少传多少就是 了，我这有个以前写的IIC控制WM8731的例程，你可以参考下

//`timescale 1ns / 1ps

module i2c_control(

clk,

i2c_sclk,

i2c_sdat,

i2c_data,

start,

tr_end,

ack,

rst,

counter,

sdo)

input clk

input [23:0]i2c_data

input start

input rst

// input w_r

inout i2c_sdat

output i2c_sclk

output tr_end

output ack

output [5:0]counter

output sdo

reg sdo

reg sclk

reg tr_end

reg [23:0]sd

reg [5:0]counter

assign i2c_sclk=sclk |(((counter>=4)&(counter<=30))?~clk:0)

assign i2c_sdat=sdo?1'bz:0

reg ack1,ack2,ack3

wire ack=ack1 |ack2 |ack3

always@(negedge rst or posedge clk)begin

if(!rst)counter<=6'b111111

else begin

if(start==0)

counter<=0

else

if(counter<6'b111111)counter<=counter+1

end

end

always@(negedge rst or posedge clk)begin

if(!rst)begin sclk<=1sdo<=1ack1<=0ack2<=0ack3<=0tr_end<=0end

else

case(counter)

6'd0 :begin ack1<=0ack2<=0ack3<=0tr_end<=0sdo<=1sclk<=1end

6'd1 :begin sd<=i2c_datasdo<=0end

6'd2 :sclk=0

6'd3 :sdo<=sd[23]

6'd4 :sdo<=sd[22]

6'd5 :sdo<=sd[21]

6'd6 :sdo<=sd[20]

6'd7 :sdo<=sd[19]

6'd8 :sdo<=sd[18]

6'd9 :sdo<=sd[17]

6'd10 :sdo<=sd[16]

6'd11 :sdo<=1'b1

6'd12 :begin sdo<=sd[15]ack1<=i2c_sdatend

6'd13 :sdo<=sd[14]

6'd14 :sdo<=sd[13]

6'd15 :sdo<=sd[12]

6'd16 :sdo<=sd[11]

6'd17 :sdo<=sd[10]

6'd18 :sdo<=sd[9]

6'd19 :sdo<=sd[8]

6'd20 :sdo<=1'b1

6'd21 :begin sdo<=sd[7]ack2<=i2c_sdatend

6'd22 :sdo<=sd[6]

6'd23 :sdo<=sd[5]

6'd24 :sdo<=sd[4]

6'd25 :sdo<=sd[3]

6'd26 :sdo<=sd[2]

6'd27 :sdo<=sd[1]

6'd28 :sdo<=sd[0]

6'd29 :sdo<=1'b1

6'd30 :begin sdo<=1'b0sclk<=1'b0ack3<=i2c_sdatend

6'd31 :sclk<=1'b1

6'd32 :begin sdo<=1'b1tr_end<=1end

endcase

end

endmodule

不是的，他无法判断你从哪读取，

读数据，首先为起始信号-》从地址（最后一位为W写）-》重复起始信号

-》从地址（最后一位为R读）-》存放的寄存器地址或读的数据地址->

读到的数据。

这么个过程。不懂的可以接着问。

建议好好看下IIC时序图就明白了

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