AHT10温湿度传感器
概念
传感器输出经过标定的数字信号输出，通过标准的I2C接口传输数据；
相对湿度的分辨率在
0.024%RH
，工作范围为
0~100%RH
；
温度值的分辨率在
0.01℃
，工作范围为
-40~85℃
；
AHT10的供电范围为
1.8~3.6V
，推荐使用
3.3V
供电；
接口包含了完全静态逻辑，因而不存在最小串行时钟SCL频率；
IIC协议，同步半双工通信协议
起始位
：主机在时钟高电平期间拉低总线；
数据位
：主机在时钟低电平期间发送数据，主机在高电平期间保持不变；从机在时钟高电平期间采样数据；
应答为
：主机收到数据后发送应答，从机才会发送下一字节数据；
停止位
：主机在时钟高电平期间释放总线，主机在低电平期间保持不变；
- 可使用的I2C通信模式有经典型和高速模式，经典模式最小时钟周期是250us,高速模式最小时钟周期是100us；
AHT10配置与通信
I2C通信通过设备地址与从机进行通信，
-
首先上电启动传感器，启动后需要先等待40ms（设备才开始正常工作），然后发送
8‘h71
来获取状态字节，状态寄存器说明如下：
获取到校准使能位后，查看其是否已校准，若已校准则跳过当前步骤；若未校准则发送
8‘hE1
，进行初始化，然后发送
8’h08
，
8‘h00
； -
接着开始触发测量，测量先发送
8’hAC
，然后发送
8‘h33
，
8'h00
； -
测量命令发送完成后，需要等待80ms，用于温湿度的测量；之后再发送命令
8‘h71
，以读取状态寄存器是否处于空闲状态（
bit7 => idle
）;若是空闲状态，可以直接读取之后六个字节的温湿度数值； -
读取温湿度数据构成
-
相对湿度和温度转换公式
将接收到的湿度值转换成%RH的格式：
RH
[
%
]
=
(
S
R
H
/
2
20
)
RH [\%] = (SRH/2^{20})
R
H
[
%
]
=
(
SR
H
/
2
20
)
温度转换成℃表示：
T(
℃
)
=
(
S
T
/
2
20
)
．
T(℃) = (ST/2^{20})．
T
(
℃
)
=
(
ST
/
2
20
)
．
设计框架
-
整个模块的设计，首先是上位机通过UART，发送命令打开AHT10驱动控制模块、数码管显示模块以及串口模块；设备驱动用控制模块实现，通信接口使用I2C与AHT10进行通信，然后将读取的温湿度值先进行数值转换并取整，并转换成ASCII码方便查看温湿度值；然后将数据缓存到FIFO中，当缓存了一组完整的温度值数据后进行输出，发送给上位机，或是直接通过数码管显示；
I2C模块
I2C接口模块状态机如上图所示，从空闲状态可以先发送起始位再读写一个字节数据，或直接读写一个字节数据，然后是收发应答位；最后发送停止位，就完成了一组数据的读写；
对于I2C通信，数据的传输速率选择的是
50M/250 Bps
;
include "param.v"
module i2c_master(
input clk ,
input rst_n ,
input req ,
input [3:0] cmd ,
input [7:0] din ,
output [7:0] dout ,
output done ,
output slave_ack ,
output i2c_scl ,
input i2c_sda_i ,
output i2c_sda_o ,
output i2c_sda_oe
);
//状态机参数定义
localparam IDLE = 7'b000_0001,
START = 7'b000_0010,
WRITE = 7'b000_0100,
RACK = 7'b000_1000,
READ = 7'b001_0000,
SACK = 7'b010_0000,
STOP = 7'b100_0000;
//
reg [6:0] state_c ;
reg [6:0] state_n ;
reg [8:0] cnt_scl ;//产生i2c时钟
wire add_cnt_scl ;
wire end_cnt_scl ;
reg [3:0] cnt_bit ;//传输数据 bit计数器
wire add_cnt_bit ;
wire end_cnt_bit ;
reg [3:0] bit_num ;
reg scl ;//输出寄存器
reg sda_out ;
reg sda_out_en ;
reg [7:0] rx_data ;
reg rx_ack ;
reg [3:0] command ;
reg [7:0] tx_data ;//发送数据
wire idle2start ;
wire idle2write ;
wire idle2read ;
wire start2write ;
wire start2read ;
wire write2rack ;
wire read2sack ;
wire rack2stop ;
wire sack2stop ;
wire rack2idle ;
wire sack2idle ;
wire stop2idle ;
//状态机
always @(posedge clk or negedge rst_n) begin
if (rst_n==0) begin
state_c <= IDLE ;
end
else begin
state_c <= state_n;
end
end
always @(*) begin
case(state_c)
IDLE :begin
if(idle2start)
state_n = START ;
else if(idle2write)
state_n = WRITE ;
else if(idle2read)
state_n = READ ;
else
state_n = state_c ;
end
START :begin
if(start2write)
state_n = WRITE ;
else if(start2read)
state_n = READ ;
else
state_n = state_c ;
end
WRITE :begin
if(write2rack)
state_n = RACK ;
else
state_n = state_c ;
end
RACK :begin
if(rack2stop)
state_n = STOP ;
else if(rack2idle)
state_n = IDLE ;
else
state_n = state_c ;
end
READ :begin
if(read2sack)
state_n = SACK ;
else
state_n = state_c ;
end
SACK :begin
if(sack2stop)
state_n = STOP ;
else if(sack2idle)
state_n = IDLE ;
else
state_n = state_c ;
end
STOP :begin
if(stop2idle)
state_n = IDLE ;
else
state_n = state_c ;
end
default : state_n = IDLE ;
endcase
end
assign idle2start = state_c==IDLE && (req && (cmd&`CMD_START));
assign idle2write = state_c==IDLE && (req && (cmd&`CMD_WRITE));
assign idle2read = state_c==IDLE && (req && (cmd&`CMD_READ ));
assign start2write = state_c==START && (end_cnt_bit && (command&`CMD_WRITE));
assign start2read = state_c==START && (end_cnt_bit && (command&`CMD_READ ));
assign write2rack = state_c==WRITE && (end_cnt_bit);
assign read2sack = state_c==READ && (end_cnt_bit);
assign rack2stop = state_c==RACK && (end_cnt_bit && (command&`CMD_STOP ));
assign sack2stop = state_c==SACK && (end_cnt_bit && (command&`CMD_STOP ));
assign rack2idle = state_c==RACK && (end_cnt_bit && (command&`CMD_STOP ) == 0);
assign sack2idle = state_c==SACK && (end_cnt_bit && (command&`CMD_STOP ) == 0);
assign stop2idle = state_c==STOP && (end_cnt_bit);
//计数器
always @(posedge clk or negedge rst_n) begin
if (rst_n==0) begin
cnt_scl <= 0;
end
else if(add_cnt_scl) begin
if(end_cnt_scl)
cnt_scl <= 0;
else
cnt_scl <= cnt_scl+1 ;
end
end
assign add_cnt_scl = (state_c != IDLE);
assign end_cnt_scl = add_cnt_scl && cnt_scl == (`SCL_PERIOD)-1 ;
always @(posedge clk or negedge rst_n) begin
if (rst_n==0) begin
cnt_bit <= 0;
end
else if(add_cnt_bit) begin
if(end_cnt_bit)
cnt_bit <= 0;
else
cnt_bit <= cnt_bit+1 ;
end
end
assign add_cnt_bit = (end_cnt_scl);
assign end_cnt_bit = add_cnt_bit && cnt_bit == (bit_num)-1 ;
always @(*)begin
if(state_c == WRITE | state_c == READ) begin
bit_num = 8;
end
else begin
bit_num = 1;
end
end
//command
always @(posedge clk or negedge rst_n)begin
if(~rst_n)begin
command <= 0;
end
else if(req)begin
command <= cmd;
end
end
//tx_data
always @(posedge clk or negedge rst_n)begin
if(~rst_n)begin
tx_data <= 0;
end
else if(req)begin
tx_data <= din;
end
end
//scl
always @(posedge clk or negedge rst_n)begin
if(~rst_n)begin
scl <= 1'b1;
end
else if(idle2start | idle2write | idle2read)begin//开始发送时，拉低
scl <= 1'b0;
end
else if(add_cnt_scl && cnt_scl == `SCL_HALF-1)begin
scl <= 1'b1;
end
else if(end_cnt_scl && ~stop2idle)begin
scl <= 1'b0;
end
end
//sda_out
always @(posedge clk or negedge rst_n)begin
if(~rst_n)begin
sda_out <= 1'b1;
end
else if(state_c == START)begin //发起始位
if(cnt_scl == `LOW_HLAF)begin //时钟低电平时拉高sda总线
sda_out <= 1'b1;
end
else if(cnt_scl == `HIGH_HALF)begin //时钟高电平时拉低sda总线
sda_out <= 1'b0; //保证从机能检测到起始位
end
end
else if(state_c == WRITE && cnt_scl == `LOW_HLAF)begin //scl低电平时发送数据 并串转换
sda_out <= tx_data[7-cnt_bit];
end
else if(state_c == SACK && cnt_scl == `LOW_HLAF)begin //发应答位
sda_out <= (command&`CMD_STOP)?1'b1:1'b0;
end
else if(state_c == STOP)begin //发停止位
if(cnt_scl == `LOW_HLAF)begin //时钟低电平时拉低sda总线
sda_out <= 1'b0;
end
else if(cnt_scl == `HIGH_HALF)begin //时钟高电平时拉高sda总线
sda_out <= 1'b1; //保证从机能检测到停止位
end
end
end
//sda_out_en 总线输出数据使能
always @(posedge clk or negedge rst_n)begin
if(~rst_n)begin
sda_out_en <= 1'b0;
end
else if(idle2start | idle2write | read2sack | rack2stop)begin
sda_out_en <= 1'b1;
end
else if(idle2read | start2read | write2rack | stop2idle)begin
sda_out_en <= 1'b0;
end
end
//rx_data 接收读入的数据
always @(posedge clk or negedge rst_n)begin
if(~rst_n)begin
rx_data <= 0;
end
else if(state_c == READ && cnt_scl == `HIGH_HALF)begin
rx_data[7-cnt_bit] <= i2c_sda_i; //串并转换
end
end
//rx_ack
always @(posedge clk or negedge rst_n)begin
if(~rst_n)begin
rx_ack <= 1'b1;
end
else if(state_c == RACK && cnt_scl == `HIGH_HALF)begin
rx_ack <= i2c_sda_i;
end
end
//输出信号
assign i2c_scl = scl ;
assign i2c_sda_o = sda_out ;
assign i2c_sda_oe = sda_out_en ;
assign dout = rx_data;
assign done = rack2idle | sack2idle | stop2idle;
assign slave_ack = rx_ack;
endmodule
`include "param.v"
module aht_ctrl (
input sys_clk ,
input rst_n ,
input driver_en ,
output req ,
output [3:0] cmd ,
output [7:0] data ,
input done ,
input [7:0] rd_data ,
output [19:0] hum_data ,
output [19:0] temp_data ,
output dout_vld
);
//
localparam START = 7'b000_0001,
INIT = 7'b000_0010,
CHECK_INIT = 7'b000_0100,
IDLE = 7'b000_1000,
TRIGGER = 7'b001_0000,
WAIT = 7'b010_0000,
READ = 7'b100_0000;
parameter DELAY_40MS = 200_0000 ,
DELAY_80MS = 400_0000 ,
DELAY_500MS = 2500_0000;
reg [7:0] state_c ;
reg [7:0] state_n ;
reg [2:0] cnt_byte ;
wire add_cnt_byte ;
wire end_cnt_byte ;
reg tx_req ;
reg [3:0] tx_cmd ;
reg [7:0] tx_data ;
reg [47:0] read_data ;
reg [27:0] cnt ;
wire add_cnt ;
wire end_cnt ;
reg [24:0] delay ;
reg finish_init ;
wire start2init ;
wire init2check ;
wire check2idle ;
wire check2init ;
wire idle2trigger ;
wire trigger2wait ;
wire wait2read ;
wire read2idle ;
reg driver_en_r1 ;
reg driver_en_r2 ;
wire ne_driver ;
// ne_driver
always@(posedge sys_clk or negedge rst_n)begin
if(!rst_n) begin
driver_en_r1 <= 0 ;
driver_en_r2 <= 0 ;
end
else begin
driver_en_r1 <= driver_en ;
driver_en_r2 <= driver_en_r1 ;
end
end
assign ne_driver = (~driver_en_r1 && driver_en_r2) ;
//state
always @(posedge sys_clk or negedge rst_n) begin
if (rst_n==0) begin
state_c <= START ;
end
else begin
state_c <= state_n;
end
end
//状态转移
always @(*) begin
case(state_c)
START :begin
if(ne_driver) begin
state_n = state_c ;
end
else if(start2init) begin
state_n = INIT ;
end
else begin
state_n = state_c ;
end
end
INIT :begin
if(ne_driver) begin
state_n = START ;
end
else if(init2check)begin
state_n = IDLE ;
end
else
state_n = state_c ;
end
CHECK_INIT :begin
if(ne_driver) begin
state_n = START ;
end
else if(check2idle)begin
state_n = IDLE ;
end
else if(check2init) begin
state_n = INIT;
end
else
state_n = state_c ;
end
IDLE :begin
if(ne_driver)begin
state_n = START ;
end
else if(idle2trigger)begin
state_n = TRIGGER ;
end
else
state_n = state_c ;
end
TRIGGER :begin
if(ne_driver)begin
state_n = START ;
end
else if(trigger2wait)begin
state_n = WAIT ;
end
else
state_n = state_c ;
end
WAIT :begin
if(ne_driver)begin
state_n = START ;
end
else if(wait2read)
state_n = READ ;
else
state_n = state_c ;
end
READ :begin
if(ne_driver)begin
state_n = START ;
end
else if(read2idle)
state_n = IDLE ;
else
state_n = state_c ;
end
default : state_n = START ;
endcase
end
assign start2init = state_c == START && (end_cnt);
assign init2check = state_c == INIT && (end_cnt_byte);
assign check2idle = state_c == CHECK_INIT && (finish_init) && end_cnt_byte;
assign check2init = state_c == CHECK_INIT && (~finish_init)&& end_cnt_byte;
assign idle2trigger = state_c == IDLE && (end_cnt);
assign trigger2wait = state_c == TRIGGER && (end_cnt_byte);
assign wait2read = state_c == WAIT && (end_cnt);
assign read2idle = state_c == READ && (end_cnt_byte);
// delay
always @(posedge sys_clk or negedge rst_n) begin
if(!rst_n) begin
delay <= DELAY_40MS;
end
else if(state_c == START) begin
delay <= DELAY_40MS;
end
else if(state_c == WAIT) begin
delay <= DELAY_80MS;
end
else if(state_c == IDLE) begin
delay <= DELAY_500MS;
end
end
// cnt
always @( posedge sys_clk or negedge rst_n ) begin
if ( !rst_n ) begin
cnt <= 0;
end
else if ( add_cnt ) begin
if ( end_cnt ) begin
cnt <= 0;
end
else begin
cnt <= cnt + 1;
end
end
else begin
cnt <= 0;
end
end
assign add_cnt = (state_c == START || state_c == WAIT || state_c == IDLE) && driver_en_r2;
assign end_cnt = cnt == delay - 1 && add_cnt || ne_driver ;
// cnt_byte
always @(posedge sys_clk or negedge rst_n) begin
if(!rst_n)begin
cnt_byte <= 0;
end
else if(add_cnt_byte) begin
if(end_cnt_byte) begin
cnt_byte <= 0;
end
else
cnt_byte <= cnt_byte + 1;
end
end
assign add_cnt_byte = (state_c == INIT || state_c == CHECK_INIT ||state_c == TRIGGER || state_c == READ) && done;
assign end_cnt_byte = (cnt_byte == (state_c == READ?6:3) && add_cnt_byte) || ne_driver ;
//
always @(*)begin
case (state_c)
INIT :
case(cnt_byte)
0 :TX(1'b1,{`CMD_START | `CMD_WRITE},{`I2C_ADR,1'b0});
1 :TX(1'b1, `CMD_WRITE ,`CMD_INIT);
2 :TX(1'b1,`CMD_WRITE ,8'b000_1000);
3 :TX(1'b1,{`CMD_WRITE | `CMD_STOP} ,8'b0000_0000);
default :TX(1'b0,tx_cmd,tx_data);
endcase
CHECK_INIT:
case(cnt_byte)
0 :TX(1'b1,{`CMD_START | `CMD_WRITE},{`I2C_ADR,1'b0});
1 :TX(1'b1,`CMD_WRITE ,`CMD_CHECK);
2 :TX(1'b1,{`CMD_START | `CMD_WRITE},{`I2C_ADR,1'b1});
3 :TX(1'b1,{`CMD_READ | `CMD_STOP},0);
default :TX(1'b0,tx_cmd,tx_data);
endcase
TRIGGER:
case(cnt_byte)
0 :TX(1'b1,{`CMD_START | `CMD_WRITE},{`I2C_ADR,1'b0});//
1 :TX(1'b1,`CMD_WRITE ,`CMD_TRIGGER);
2 :TX(1'b1,`CMD_WRITE ,`DATA_0);
3 :TX(1'b1,{`CMD_WRITE | `CMD_STOP},`DATA_1);
default :TX(1'b0,tx_cmd,tx_data);
endcase
READ :
case(cnt_byte)
0 :TX(1'b1,{`CMD_START | `CMD_WRITE},{`I2C_ADR,1'b1});
1 :TX(1'b1,`CMD_READ ,0);
2 :TX(1'b1,`CMD_READ ,0);
3 :TX(1'b1,`CMD_READ ,0);
4 :TX(1'b1,`CMD_READ ,0);
5 :TX(1'b1,`CMD_READ ,0);
6 :TX(1'b1,{`CMD_READ | `CMD_STOP},0);
default :TX(1'b0,tx_cmd,tx_data);
endcase
default: TX(1'b0,0,0);
endcase
end
// finish_init
always @(posedge sys_clk or negedge rst_n) begin
if(!rst_n) begin
finish_init <= 0;
end
else if(state_c == CHECK_INIT && done && rd_data[3]) begin
finish_init <= 1;
end
end
// read_data
always @(posedge sys_clk or negedge rst_n) begin
if(!rst_n) begin
read_data <= 0;
end
else if(state_c == READ && cnt_byte >0 && done) begin
read_data <= {read_data[39:0],rd_data};
end
end
//
task TX;
input req ;
input [3:0] command ;
input [7:0] data ;
begin
tx_req = req;
tx_cmd = command;
tx_data = data;
end
endtask
//out
assign req = tx_req ;
assign cmd = tx_cmd ;
assign data = tx_data;
assign hum_data = read_data[39:20];
assign temp_data = read_data[19:0];
assign dout_vld = read2idle;
endmodule
其它模块
然后将温湿度数值按照上述格式转换：
temp_data_r <= (((temp_data*2000)>>12) - (500));
hum_data_r <= ((hum_data *1000) >> 12);
再将数据转换成ASCII码:
always@(posedge sys_clk or negedge rst_n)begin
case (cnt)
1 : dout_r <= 8'hce;
2 : dout_r <= 8'hc2;
3 : dout_r <= 8'hb6;
4 : dout_r <= 8'hc8;
5 : dout_r <= 8'h3a;
6 : dout_r <= (temp_data_r / 100 % 10 )+48;
7 : dout_r <= (temp_data_r / 10 % 10 )+48;
8 : dout_r <= 8'h2e;
9 : dout_r <= (temp_data_r % 10 )+48;
10 : dout_r <= 8'ha1;
11 : dout_r <= 8'he6;
12: dout_r <= 9;
13: dout_r <= 8'hca;
14: dout_r <= 8'haa;
15: dout_r <= 8'hb6;
16: dout_r <= 8'hc8;
17: dout_r <= 8'h3a;
18: dout_r <= (hum_data_r / 100 % 10 )+48;
19: dout_r <= (hum_data_r / 10 % 10 )+48;
20: dout_r <= 8'h2e;
21: dout_r <= (hum_data_r % 10 )+48;
22: dout_r <= 8'h25;
default: dout_r <= 0;
endcase
end
最后将数值通过FIFO缓存完整的22字节数据后输出即可；
同时还可以将数据转换成bcd码显示到数码管上；
版权声明：本文为qq_50670020原创文章，遵循 CC 4.0 BY-SA 版权协议，转载请附上原文出处链接和本声明。