I am trying to connect a temperature sensor to my Raspberry Pi using this tutorial for Windows IoT Core.
I have connected all of the wires and MCP3002 correctly, but I cannot read in any values from my sensor when the app is deployed and run.
The sensor listed in the tutorial is the TMP36GZ and I have also tried a DS1822 for debugging purposes. Neither of them produce an error when connected the right way around, but the output is always 0.
I have swapped out the temp sensors for a potentiometer and that has been able to return values and print them to the screen.
All of the code is in C# and can be found on the linked tutorial.
Update: Connected MCP3002 Pin 8 to 5V along with keeping the connection to the right leg of the TMP36GZ. Outputted values now hover between 158-164 even when held in hand etc(there is no reaction to heat). The temperature in the room is around 15-16C too. That would make sense to divide the output by 10, although I need to be able to measure an increase/decrease in heat when it is touched. I connected the potentiometer again and this produced accurate results from 0-1200 depending on the position of the knob.
My MainPage.xaml.cs:
`namespace TempSensor { /// /// An empty page that can be used on its own or navigated to within a Frame. /// public sealed partial class MainPage : Page { enum ADCChip { mcp3002, // 2 channel 10 bit mcp3008, // 8 channel 10 bit mcp3208 // 8 channel 12 bit } ADCChip whichADCChip = ADCChip.mcp3002;
public MainPage()
{
this.InitializeComponent();
this.InitializeComponent();
timer = new DispatcherTimer();
timer.Interval = TimeSpan.FromMilliseconds(500);
timer.Tick += Timer_Tick;
timer.Start();
whichADCChip = ADCChip.mcp3002;
switch (whichADCChip)
{
case ADCChip.mcp3002:
{
// To line everything up for ease of reading back (on byte boundary) we
// will pad the command start bit with 1 leading "0" bit
// Write 0SGO MNxx xxxx xxxx
// Read ???? ?N98 7654 3210
// S = start bit
// G = Single / Differential
// O = Chanel data
// M = Most significant bit mode
// ? = undefined, ignore
// N = 0 "Null bit"
// 9-0 = 10 data bits
// 0110 1000 = 1 0 pad bit, start bit, Single ended, odd (channel 0), MSFB only, 2 clocking bits
// 0000 0000 = 8 clocking bits
readBuffer = new byte[2] { 0x00, 0x00 };
writeBuffer = new byte[2] { 0x68, 0x00 };
}
break;
case ADCChip.mcp3008:
{
// To line everything up for ease of reading back (on byte boundary) we
// will pad the command start bit with 7 leading "0" bits
// Write 0000 000S GDDD xxxx xxxx xxxx
// Read ???? ???? ???? ?N98 7654 3210
// S = start bit
// G = Single / Differential
// D = Chanel data
// ? = undefined, ignore
// N = 0 "Null bit"
// 9-0 = 10 data bits
// 0000 01 = 7 pad bits, start bit
// 1000 0000 = single ended, channel bit 2, channel bit 1, channel bit 0, 4 clocking bits
// 0000 0000 = 8 clocking bits
readBuffer = new byte[3] { 0x00, 0x00, 0x00 };
writeBuffer = new byte[3] { 0x01, 0x80, 0x00 };
}
break;
case ADCChip.mcp3208:
{
/* mcp3208 is 12 bits output */
// To line everything up for ease of reading back (on byte boundary) we
// will pad the command start bit with 5 leading "0" bits
// Write 0000 0SGD DDxx xxxx xxxx xxxx
// Read ???? ???? ???N BA98 7654 3210
// S = start bit
// G = Single / Differential
// D = Chanel data
// ? = undefined, ignore
// N = 0 "Null bit"
// B-0 = 12 data bits
// 0000 0110 = 5 pad bits, start bit, single ended, channel bit 2
// 0000 0000 = channel bit 1, channel bit 0, 6 clocking bits
// 0000 0000 = 8 clocking bits
readBuffer = new byte[3] { 0x00, 0x00, 0x00 };
writeBuffer = new byte[3] { 0x00, 0x00, 0x00 };
}
break;
}
InitSPI();
}
private async void InitSPI()
{
try
{
var settings = new SpiConnectionSettings(SPI_CHIP_SELECT_LINE);
settings.ClockFrequency = 500000;// 10000000;
settings.Mode = SpiMode.Mode0; //Mode3;
var controller = await SpiController.GetDefaultAsync();
SpiDisplay = controller.GetDevice(settings);
GpioStatus.Text = "Successfully Initialised GPIO";
}
/* If initialization fails, display the exception and stop running */
catch (Exception ex)
{
throw new Exception("SPI Initialization Failed", ex);
}
}
private void Timer_Tick(object sender, object e)
{
DisplayTextBoxContents();
}
public void DisplayTextBoxContents()
{
SpiDisplay.TransferFullDuplex(writeBuffer, readBuffer);
res = convertToInt(readBuffer);
textPlaceHolder.Text = res.ToString();
}
public int convertToInt(byte[] data)
{
int result = 0;
switch (whichADCChip)
{
case ADCChip.mcp3002:
{
/*mcp3002 10 bit output*/
result = data[0] & 0x03;
result <<= 8;
result += data[1];
}
break;
case ADCChip.mcp3008:
{
/*mcp3008 10 bit output*/
result = data[1] & 0x03;
result <<= 8;
result += data[2];
}
break;
case ADCChip.mcp3208:
{
/* mcp3208 is 12 bits output */
result = data[1] & 0x0F;
result <<= 8;
result += data[2];
}
break;
}
return result;
}
/*Raspberry Pi2 Parameters*/
private const string SPI_CONTROLLER_NAME = "SPI0"; /* For Raspberry Pi 2, use SPI0 */
private const Int32 SPI_CHIP_SELECT_LINE = 0; /* Line 0 maps to physical pin number 24 on the Rpi2 */
byte[] readBuffer = null; /* this is defined to hold the output data*/
byte[] writeBuffer = null; /* we will hold the command to send to the chipbuild this in the constructor for the chip we are using */
private SpiDevice SpiDisplay;
// create a timer
private DispatcherTimer timer;
int res;
}
} `
