![\"PCF8591\"](\"https:\/\/i0.wp.com\/einhugur.com\/blog\/wp-content\/uploads\/2016\/05\/PCF8591.jpg?resize=400%2C240&ssl=1\")
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Disclaimer:<\/strong> Pieces we use in this example:<\/strong><\/p>\n If you are not familiar with breadboards, how to place a cobbler on the breadboard or need to know how to read the color codings on the resistors then click here bellow<\/strong><\/p>\n \u00a0<\/i>\u00a0 Using breadboard<\/a> \u00a0<\/i>\u00a0 Resistor color codings<\/a><\/p>\n To install the I2CTools you use the following command:<\/p>\n sudo apt-get\u00a0install i2c-tools<\/p><\/blockquote>\n You need to enable\u00a0the i2c bus in the Raspberry PI settings, which you can do in the user interface if your running Jessie or if your on older system then you can do it in console.<\/p>\n Understanding the\u00a0PCF8591 AD\/DA Converter board:<\/strong><\/p>\n This board operates at 5V, it has 4 analog inputs, and one analog output. Each analog channel is converted to 8 bit value (0 – 255).<\/p>\n The board comes with the three jumpers on as can be seen on the picture bellow:<\/p>\n On the board there is a light sensor, a temperature\u00a0sensor and potentiometer. (Why would anyone want that ? I don’t know since those are not high quality sensors). But by default the light sensor is taking analog input 0, the temperature sensor is taking analog input 1 and the\u00a0potentiometer is wired to analog input 3, leaving only analog input 2 unused. By taking off the jumpers then you can disable those sensors and get all the analog channels for your use.<\/p>\n P4 – Taking off P4 disconnects the temperature sensor and gives you analog channel 1 for your own use.<\/em><\/p>\n P5- Taking off P4 disconnects the light\u00a0sensor and gives you analog channel 0 for your own use.<\/em><\/p>\n P6- Taking off P6 disconnects the 10K\u03a9 potentiometer\u00a0and gives you analog channel 3 for your own use.<\/em><\/p>\n We just take them all off for our test, I don’t see good purpose for those sensor on this board anyhow, then the board will look like this with all 4 inputs enabled:<\/p>\n The analog inputs go from 0 to 5 V This means for the inputs then the following applies:<\/p>\n And for the output then the following applies:<\/p>\n Wiring up the board:<\/strong><\/p>\n We use the 2 k\u03a9 resistors\u00a0to pull down the analog channels to prevent them from having fluctuating state. If you don’t plan to read all the analog channels then its enough to have pull down resistor on the channels that you want to use.<\/p>\n Note also the two 15 k\u03a9 resistors which we use to\u00a0pull down the voltage to safe levels for the I2C bus.<\/p>\n Then analog device can be connected to one of the red dots on the scheme above. We will just be connecting 3,3 V from PIN 1 on the Raspberry PI to one of the analog channels. (one of the red dots).<\/p>\n We have put voltage\u00a0meter on the output so we can watch how to voltage changes depending on how much output we apply on the \u00a0analog output channel. We also put a LED there. The LED will not turn on on the lower voltages.<\/p>\n Here is one way to put it on the breadboard. (Try to go by scheme drawing rather than breadboard drawing to avoid mistakes and to gain more understanding)<\/p>\n Blue wire we connected to 39 (GND) Sanity tests in console:<\/strong><\/p>\n After you have connected everything and made sure that wiringPI, i2ctools are installed\u00a0that I2C is enabled in the Raspberry PI settings, then we are ready to do sanity tests in console.<\/p>\n First thing is getting the address of the I2C device, which is in this case the analog converter board.<\/p>\n To do that then we type:<\/p>\n sudo i2cdetect -y 1<\/p><\/blockquote>\n This should show our device at 0x48 (if you got exactly same type of device – many other devices also use 0x48)<\/p>\n Test reading the channels (we always read twice since this device will in first read return last value set even if it was on different channel)<\/p>\n We select channel 0, and then read it twice (ignoring the first value).<\/p>\n i2cset -y 1 0x48 0x00 We select channel 1, and then read it twice (ignoring the first value).<\/p>\n i2cset -y 1 0x48 0x01 We select channel 2, and then read it twice (ignoring the first value).<\/p>\n i2cset -y 1 0x48 0x02 We select channel 3, and then read it twice (ignoring the first value).<\/p>\n i2cset -y 1 0x48 0x03 Note if your reading same channel over and over again like a stream feed then you don’t need to read twice as previous value will be from same channel making it a valid value.<\/p>\n Now we test writing to the analog output full voltage:<\/p>\n i2cset -y 1 0x48 0x41 0xff<\/p><\/blockquote>\n Now we test writing to the analog output zero\u00a0voltage:<\/p>\n i2cset -y 1 0x48 0x41 0x0<\/p><\/blockquote>\n<\/blockquote>\n Now we test writing to the analog output half\u00a0voltage:<\/p>\n i2cset -y 1 0x48 0x41 0x80<\/p><\/blockquote>\n<\/blockquote>\n<\/blockquote>\n<\/blockquote>\n Putting it all in Xojo:<\/strong><\/p>\n We create a module called I2C and add the following functions to it, making their scope as Protected<\/p>\n Then we put\u00a04 buttons on a window to read channel 0 to 3:<\/p>\n Then we put slider on the window, setting its initial value to 0, and min as 0 and max as 255. Here is Open event and ValueChanged events for the slider:<\/p>\n Downloading the code:<\/strong><\/p>\n \u00a0<\/i>\u00a0 Download the code<\/a><\/p>\n When testing then you can test connecting 3,3 V to the analog inputs and see how it changes.<\/p>\n Having mastered this will enable usage of many analog sensors and devices.<\/p>\n Note that a better way to hook up the PCF8591\u00a0is to use I2C logic converter than to use the 15k\u03a9 resistors, like for example:<\/p>\n You can see more about that in our\u00a0Building I2C logic converter guide.<\/a><\/p>\n <\/p>\n In this example we are going to connect to PCF8591 AD\/DA Converter. Raspberry PI has no Analog inputs\u00a0or outputs, so to talk to analog devices we need to convert the signal. Updated 6. May 2016 – Added R6 and R7 to get the voltage to safe levels on the I2C bus. Disclaimer: We do not … Continue reading PCF8591 Analog To Digital<\/span>
\nWe do not take any responsibility for possible errors in the guide or errors that you might do wiring it up. Incorrect wiring can result in damaged sensor or damaged Raspberry PI.<\/p>\n\n
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\n![\"PCF8591WithJumpers\"](\"https:\/\/i1.wp.com\/einhugur.com\/blog\/wp-content\/uploads\/2016\/05\/PCF8591WithJumpers.jpg?resize=400%2C260&ssl=1\")
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\nThe analog output maxed for me at 3,64 V (It’s good to measure to know what your dealing with so you can account for it in your design as cheap circuits are not always as they claim to be).<\/p>\n\n
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![\"PCF8591SchemeView2\"](\"https:\/\/i2.wp.com\/einhugur.com\/blog\/wp-content\/uploads\/2016\/05\/PCF8591SchemeView2.png?resize=474%2C253&ssl=1\")
<\/a><\/p>\n![\"PCF8591BBView2\"](\"https:\/\/i0.wp.com\/einhugur.com\/blog\/wp-content\/uploads\/2016\/05\/PCF8591BBView2.png?resize=474%2C286&ssl=1\")
<\/a><\/p>\n![\"GPIO](\"https:\/\/i1.wp.com\/einhugur.com\/blog\/wp-content\/uploads\/2015\/09\/GPIO-Header-152x300.png?resize=152%2C300&ssl=1\")
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\nRed to 4 (5V)
\nGreen to pin 3 marked as GPIO 2 here above (Its a special GPIO pin that is also called SDA, you cannot choose any other pin for this)
\nGray to the pin marked as GPIO 3 here above (Its a special pin that is also called SCL, you cannot choose any other pin for this).<\/p>\n
\ni2cget -y 1 0x48
\ni2cget -y 1 0x48<\/p><\/blockquote>\n\n
\ni2cget -y 1 0x48
\ni2cget -y 1 0x48<\/p><\/blockquote>\n<\/blockquote>\n\n
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\ni2cget -y 1 0x48
\ni2cget -y 1 0x48<\/p><\/blockquote>\n<\/blockquote>\n<\/blockquote>\n<\/blockquote>\n\n
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\ni2cget -y 1 0x48
\ni2cget -y 1 0x48<\/p><\/blockquote>\n<\/blockquote>\n<\/blockquote>\n<\/blockquote>\n<\/blockquote>\n<\/blockquote>\n<\/blockquote>\n<\/blockquote>\n\n
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Protected Function Setup(devID As Int32) As Int32\r\n #If TargetARM And TargetLinux Then\r\n Soft Declare Function wpWiringPiI2CSetup Lib \"libwiringPi.so\" alias \"wiringPiI2CSetup\" (devID as Integer) as Integer\r\n Return wpWiringPiI2CSetup(devID)\r\n #Endif\r\nEnd Function\r\n\r\nProtected Function ReadReg8(fd as Integer, reg as Integer) As Integer\r\n #If TargetARM And TargetLinux Then\r\n Soft Declare Function wpWiringPiI2CReadReg8 Lib \"libwiringPi.so\" alias \"wiringPiI2CReadReg8\" (fd as Integer, reg as Integer) as Integer\r\n Return wpWiringPiI2CReadReg8(fd, reg)\r\n #Endif\r\n \r\nEnd Function\r\n\r\nProtected Function WriteReg8(fd as Integer, reg As Int32, data as Integer) As Integer\r\n #If TargetARM And TargetLinux Then\r\n Soft Declare Function wpWiringPiI2CWriteReg8 Lib \"libwiringPi.so\" alias \"wiringPiI2CWriteReg8\" (fd as Integer, reg as Integer, data as Integer) As Integer\r\n Return wpWiringPiI2CWriteReg8(fd, reg, data)\r\n #Endif\r\n \r\nEnd Function\r\n<\/pre>\n
\/\/ Button to read channel 0\r\nSub Action()\r\n Dim handle as Integer\r\n Dim value as Integer\r\n \r\n handle = I2C.Setup(&h48)\r\n \r\n if handle = -1 then\r\n MsgBox \"Failed I2CSetup\"\r\n return\r\n end if\r\n \r\n if handle <> -1 then\r\n \/\/ I am reading twice so I dont get previous value from different channel, if your always reading just same channel in tight loop then its ok to just read once\r\n \/\/ The value in the first reading might have no meaning since the way this board works then when you ask for value then your getting value from previous state.\r\n value = I2C.ReadReg8(handle,&h0)\r\n value = I2C.ReadReg8(handle,&h0) \/\/ At this point we know for sure that the previous state was &h0 so we get valid value\r\n \r\n MsgBox \"Raw value: \" + Str(value) + EndOfLine + \"Voltage: \" +Format(value \/ 255.0 * 5.0,\"#.##\") + \" V\"\r\n end if\r\nEnd Sub\r\n\r\n\/\/ Button to read channel 1\r\nSub Action()\r\n Dim handle as Integer\r\n Dim value as Integer\r\n \r\n handle = I2C.Setup(&h48)\r\n \r\n if handle = -1 then\r\n MsgBox \"Failed I2CSetup\"\r\n return\r\n end if\r\n \r\n if handle <> -1 then\r\n \/\/ I am reading twice so I dont get previous value from different channel, if your always reading just same channel in tight loop then its ok to just read once\r\n \/\/ The value in the first reading might have no meaning since the way this board works then when you ask for value then your getting value from previous state.\r\n value = I2C.ReadReg8(handle,&h1)\r\n value = I2C.ReadReg8(handle,&h1) \/\/ At this point we know for sure that the previous state was &h1 so we get valid value\r\n \r\n MsgBox \"Raw value: \" + Str(value) + EndOfLine + \"Voltage: \" +Format(value \/ 255.0 * 5.0,\"#.##\") + \" V\"\r\n end if\r\nEnd Sub\r\n\r\n\/\/ Button to read channel 2\r\nSub Action()\r\n Dim handle as Integer\r\n Dim value as Integer\r\n \r\n handle = I2C.Setup(&h48)\r\n \r\n if handle = -1 then\r\n MsgBox \"Failed I2CSetup\"\r\n return\r\n end if\r\n \r\n if handle <> -1 then\r\n \/\/ I am reading twice so I dont get previous value from different channel, if your always reading just same channel in tight loop then its ok to just read once\r\n \/\/ The value in the first reading might have no meaning since the way this board works then when you ask for value then your getting value from previous state.\r\n value = I2C.ReadReg8(handle,&h2)\r\n value = I2C.ReadReg8(handle,&h2) \/\/ At this point we know for sure that the previous state was &h2 so we get valid value\r\n \r\n MsgBox \"Raw value: \" + Str(value) + EndOfLine + \"Voltage: \" +Format(value \/ 255.0 * 5.0,\"#.##\") + \" V\"\r\n end if\r\nEnd Sub\r\n\r\n\/\/ Button to read channel 3\r\n Sub Action()\r\n Dim handle as Integer\r\n Dim value as Integer\r\n \r\n handle = I2C.Setup(&h48)\r\n \r\n if handle = -1 then\r\n MsgBox \"Failed I2CSetup\"\r\n return\r\n end if\r\n \r\n if handle <> -1 then\r\n \/\/ I am reading twice so I dont get previous value from different channel, if your always reading just same channel in tight loop then its ok to just read once\r\n \/\/ The value in the first reading might have no meaning since the way this board works then when you ask for value then your getting value from previous state.\r\n value = I2C.ReadReg8(handle,&h3)\r\n value = I2C.ReadReg8(handle,&h3) \/\/ At this point we know for sure that the previous state was &h3 so we get valid value\r\n \r\n MsgBox \"Raw value: \" + Str(value) + EndOfLine + \"Voltage: \" +Format(value \/ 255.0 * 5.0,\"#.##\") + \" V\"\r\n end if\r\nEnd Sub\r\n<\/pre>\n
Sub Open()\r\n Dim handle as Integer\r\n \r\n handle = I2C.Setup(&h48)\r\n \r\n if handle = -1 then\r\n MsgBox \"Failed I2CSetup\"\r\n return\r\n end if\r\n \r\n if handle <> -1 then\r\n call I2C.WriteReg8(handle,&h41,0)\r\n end if\r\nEnd Sub\r\n\r\nSub ValueChanged()\r\n Dim handle as Integer\r\n \r\n handle = I2C.Setup(&h48)\r\n \r\n if handle = -1 then\r\n MsgBox \"Failed I2CSetup\"\r\n return\r\n end if\r\n \r\n if handle <> -1 then\r\n call I2C.WriteReg8(handle,&h41,me.Value)\r\n end if\r\nEnd Sub\r\n<\/pre>\n
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\n![\"WithLogicConverter\"](\"https:\/\/i0.wp.com\/einhugur.com\/blog\/wp-content\/uploads\/2016\/05\/WithLogicConverter.png?resize=474%2C141&ssl=1\")
<\/a><\/p>\n
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AliExpress.com Product – HoldPeak HP-770D Multimeter<\/span><\/a><\/p>\n![](\"https:\/\/i2.wp.com\/g03.a.alicdn.com\/kf\/HTB1uYtsIXXXXXa7XFXXq6xXFXXXY\/1-4W-0-25W-122-kind-20-PCs-2440-PCs-0-33ohm-4-7m-5-carbon.jpg_220x220.jpg?w=474\")
AliExpress.com Product – 1\/4W 0.25W 122 kind * 20 PCs =2440 PCs (0.33ohm-4.7m) 5% carbon film resistors assorted kit<\/span><\/a><\/p>\n![](\"https:\/\/i2.wp.com\/g03.a.alicdn.com\/kf\/HTB13t44LpXXXXauXFXXq6xXFXXXp\/-font-b-PCF8591-b-font-module-AD-DA-converter-module-font-b-analog-b-font.jpg_220x220.jpg?w=474\")
AliExpress.com Product – PCF8591 module AD \/ DA converter module analog to digital \/ digital to analog conversion<\/span><\/a><\/p>\n","protected":false},"excerpt":{"rendered":"