圣龙扬特-AVR电子

标题: 1N4148温度计(ADC by ADS1115) [打印本页]

作者: 箫天 时间: 2020-3-8 13:23
标题: 1N4148温度计(ADC by ADS1115)
　　正当疫情，需要经常测量体温，宿舍没有温度计。就用1N4148做感温头做了一个，使用效果很好。
　　二极管对温度十分敏感，温度的变化将改变它的管压降。温度上升时管压降减小；温度下降时管压降增加。　　二极管(1N4148)的平均灵敏度约为-2mV/℃。由于它的线性度相当好，所以平均灵敏度可看作二极管的测温灵敏度。即温度每上升1℃时，管压降下降了2mV左右。
　　在海平面一个大气压的条件下，水的沸腾温度为100℃；在冰与水共溶的条件下其温度为0℃。在沿海一带或海拔不高的地区可以认为沸腾的水是100℃(误差不大)。
　　将100℃及0℃两个温度值作为标准温度来标定温度与管压降之间的定量关系。用沸水和冰水混合物分别标定100℃和0℃的管压降，测得100℃<->0.4124V 、0℃<->0.6184V。
　　线性拟合: y=a+bx ，Coefficient Data: a = 3.00194174757E+002 ，b = -4.85436893204E+002
　　电路中电压3.3V，串联4.7K电阻。
　　采样使用ADS1115（http://avr.cnta.net/forum.php?mod=viewthread&tid=83435），量程设置为 ±1.024V 。

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      '  *********************************************
      '  *    1N4148温度计(ADC by ADS1115)       *
      '  *             (Ver 0.01)                *
      '  *       Copyright By Slyt 2020.2.22    *
      '  *********************************************
'.....................................................................................
'(
二极管对温度十分敏感，温度的变化将改变它的管压降。温度上升时管压降减小；温度下降时管压降增加。
二极管(1N4148)的平均灵敏度约为-2mV/℃。由于它的线性度相当好，所以平均灵敏度可看作二极管的测温灵敏度。即温度每上升1℃时，管压降下降了2mV左右。
在海平面一个大气压的条件下，水的沸腾温度为100℃；在冰与水共溶的条件下其温度为0℃。在沿海一带或海拔不高的地区可以认为沸腾的水是100℃(误差不大)。
将100℃及0℃两个温度值作为标准温度来标定温度与管压降之间的定量关系。用沸水和冰水混合物分别标定100℃和0℃的管压降，测得100℃<->0.4124V 、0℃<->0.6184V。
线性拟合:  y=a+bx ，Coefficient Data: a = 3.00194174757E+002 ，b = -4.85436893204E+002
电路中电压3.3V，串联4.7K电阻。
采样使用ADS1115（http://avr.cnta.net/forum.php?mod=viewthread&tid=83435），量程设置为 ±1.024V 。
')
'.....................................................................................
$regfile = "m8def.dat"                                     ' specify the used micro
$crystal = 8000000                                        ' used crystal frequency
'$baud = 19200                                           ' use baud rate
$hwstack = 32                                              ' default use 32 for the hardware stack
$swstack = 32                                              ' default use 10 for the SW stack
$framesize = 64                                           ' default use 40 for the frame space
Osccal = &H9F

'.....................................................................................
Config Lcdpin = Pin , Db4 = Portd.4 , Db5 = Portd.5 , Db6 = Portd.6 , Db7 = Portd.7 , Rs = Portb.0 , E = Portb.1
Config Lcd = 16 * 2                                        'configure lcd screen
Cursor Off Noblink

'Configure pins to to use for the I2C bus
Config Scl = Portb.7                                     'Is serial clock SCL
Config Sda = Portb.6                                     'Is serial data SDA
I2cinit

Deflcdchar 0 , 23 , 8 , 8 , 8 , 8 , 8 , 7 , 32             ' replace [x] with number (0-7)

'.....................................................................................
Declare Function Get_adc(byval Ain_x As Byte) As Integer

'.....................................................................................
Dim Mylong As Long
Dim Voltage As Single
Dim Vol_str As String * 10

'(
Write to Config register:
First byte: 0b10010000 (first 7-bit I2C address followed by a low read/write bit) (H90/H91 OK)

Second byte: 0b00000001 (points to Config register)
Third byte: 0b10000100 (MSB of the Config register to be written)
Fourth byte: 0b10000011 (LSB of the Config register to be written)

Write to Pointer register:
First byte: 0b10010000 (first 7-bit I2C address followed by a low read/write bit) (H90/H91 OK)
Second byte: 0b00000000 (points to Conversion register)

Read Conversion register:
First byte: 0b10010001 (first 7-bit I2C address followed by a high read/write bit)
Second byte: the ADS1113/4/5 response with the MSB of the Conversion register
Third byte: the ADS1113/4/5 response with the LSB of the Conversion register
')

'在14-12位，是 MUX 配置，决定了 ADS1115 的 A0-A3 接口的测量方式。
'比如，当设置为 0x04 时测量的为 A0-GND 的电压，当设置为 0x00 时测量的为 A0-A1 间的电压。
Dim Channel(8) As Byte
'AIN0-AIN1             'AIN0-AIN3             'AIN1-AIN3             'AIN2-AIN3
Channel(5) = &B00000000 : Channel(6) = &B00010000 : Channel(7) = &B00100000 : Channel(8) = &B00110000
'AIN0-GND                'AIN1-GND                'AIN2-GND                'AIN3-GND
Channel(1) = &B01000000 : Channel(2) = &B01010000 : Channel(3) = &B01100000 : Channel(4) = &B01110000

'Dim V100 As Single                                        '0.4124V 100C
'Dim V000 As Single                                        '0.6184V    0C
Dim Vnow As Single
Dim A As Single
Dim B As Single
A = 3.00194174757e002
B = -4.85436893204e002
'(
线性拟合:  y=a+bx
Coefficient Data:
a = 3.00194174757E+002
b = -4.85436893204E+002
')

'*************************************************************************************
Cls
Do
Mylong = Get_adc(1)

Voltage = Mylong / 32768
Voltage = Voltage * 10240
Mylong = Round(voltage)
Vol_str = Str(mylong)
Vol_str = Format(vol_str , "0.0000") + " "
Locate 1 , 1
Lcd Vol_str

Vnow = Val(vol_str)
Voltage = B * Vnow
Voltage = A + Voltage
Voltage = Voltage * 10
Mylong = Round(voltage)
Vol_str = Str(mylong)
Vol_str = Format(vol_str , "0.0") + " "
Locate 2 , 1
Lcd Vol_str
Locate 2 , 6
Lcd Chr(0)

Waitms 500
Loop
End

'*************************************************************************************
Function Get_adc(byval Ain_x As Byte) As Integer
'(
'在11-9位，是 PGA 配置，决定 ADS1115 的量程。
Dim Pga(8) As Byte
'FS=±6.144V       'FS=±4.096V       'FS=±2.048V       'FS=±1.024V
Pga(1) = &B00000000 : Pga(2) = &B00000010 : Pga(3) = &B00000100 : Pga(4) = &B00000110
'FS=±0.512V       'FS=±0.256V       'FS=±0.256V       'FS=±0.256V
Pga(5) = &B00001000 : Pga(6) = &B00001010 : Pga(7) = &B00001100 : Pga(8) = &B00001110
')

'(
'在第7-5位，是每秒采样次数的配置。
Dim Data_rate(8) As Byte
'8SPS                   '16SPS                   '32SPS                   '64SPS
Data_rate(1) = &B00000000 : Data_rate(2) = &B00100000 : Data_rate(3) = &B01000000 : Data_rate(4) = &B01100000
'128SPS                   '250SPS                   '475SPS                   '860SPS
Data_rate(5) = &B10000000 : Data_rate(6) = &B10100000 : Data_rate(7) = &B11000000 : Data_rate(8) = &B11100000
')

Local Config_high As Byte
Local Config_low As Byte

Config_high = &B10000000
'Ain_x-> 1-8
If Ain_x > 8 Or Ain_x < 1 Then Ain_x = 1
Config_high = Config_high + Channel(ain_x)

'Config_high = Config_high + &B00000010                ' Pga(2)  ±4.096V
Config_high = Config_high + &B00000110                ' Pga(4)  ±1.024V

'Config_low = &B00000000
'Config_low = Config_low + Data_rate(5)
Config_low = &B10000000                               ' 128SPS

'init I2C
I2cstart
I2cwbyte &H90                                           ' W_addr
I2cwbyte &B00000001                                     ' 指向Config寄存器
I2cwbyte Config_high
I2cwbyte Config_low
I2cstop

'Read_ad
I2cstart                                              ' Generate start code
I2cwbyte &H90                                           ' W_addr                   ' send address
I2cwbyte &B00000000                                     ' 指向AD转换寄存器
I2cstart                                              ' start condition
I2cwbyte &H91                                           ' R_addr                   ' slave address
I2crbyte Config_high , Ack
I2crbyte Config_low , Nack
I2cstop

Get_adc = Makeint(config_low , Config_high)
End Function

'-------------------------------------------------------------------------------------

作者: xhele 时间: 2020-3-18 07:32
AVR我只会用ICCAVR软件，这个得学习一下

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