B4R Question [SOLVED] MAX6675 & esp8266 anyone?

[giggetto71]

Hi,
does anyone have successfully connected a MAX6675 thermocouple board with a esp8266 (nodemcu or wemos)? I know that there is an arduino library but looking at the community that lib has not been wrapped yet. I have also seen that that the board can communicate over spi so I was tempted to make a test with the existing rSPI library but I never played with spi so I was wondering if anyone has anything I could start from.
thanks!

 

[thetahsk]

Hi,

First install the adafruit lib from here
https://github.com/adafruit/MAX6675-library and adapt D0,CS and CLK according to your board.

For the MAX6675 to update, you must delay AT LEAST 250ms between reads, use a timer or use CallSubPlus.

Sub Process_Globals
    Public Serial1 As Serial
End Sub

Private Sub AppStart
    Serial1.Initialize(115200)
    Dim tc_f As Float = RunNative("read_tc_f",Null)
    '// For the MAX6675 to update, you must delay AT LEAST 250ms between reads!
    Dim tc_c As Float = RunNative("read_tc_c",Null)
    Log("Temp:[C]: ",tc_c)
    Log("Temp:[F]: ",tc_f)
End Sub

#if C
#include "max6675.h"

int thermoDO = 4;int thermoCS = 5;int thermoCLK = 6;
B4R::Object res;
MAX6675 thermocouple(thermoCLK, thermoCS, thermoDO);

B4R::Object* read_tc_f (B4R::Object* o) {
   return res.wrapNumber(thermocouple.readFahrenheit());
}

B4R::Object* read_tc_c (B4R::Object* o) {
   return res.wrapNumber(thermocouple.readCelsius());
}
#End if

 

[giggetto71]

thanks @thetahsk ! this really looks what I need! did not have time to test as I was out for work this week but as usual great support!

 

[rwblinn]

Just to share in addition to the Inline C solution, a wrapped MAX6675 library rMAX6675 which I am using for Home Automation Solution reading the Heating Flow Temperature with PT100.

'This basic example reads the thermosensor every 10 seconds and logs the temperature in C. Tested with Arduino UNO.
Sub Process_Globals
    Public serialLine As Serial
    'MAX6675
    Private maxx As MAX6675
    Private PINSCK As Byte = 10
    Private PINCS As Byte = 9
    Private PINSO As Byte = 8
    'Timer for reading
    Private timerRead As Timer
    Private READ_INTERVAL As ULong = 10000
End Sub

Private Sub AppStart
    serialLine.Initialize(115200)
    maxx.Initialize(PINSCK, PINCS, PINSO)
    timerRead.Initialize("TimerRead_Tick", READ_INTERVAL)
    timerRead.Enabled = True
    TimerRead_Tick
End Sub

Sub TimerRead_Tick
    'Temperature=20.7 Celsius
    Log("Temperature=", NumberFormat(maxx.ReadCelsius, 0, 1), " Celsius")
End Sub

 

[giggetto71]

thanks. just one (stupid) question. the above zip does contain the xml file. Did I miss something ?

 

[rwblinn]

thanks. the above zip does contain the xml file. Did I miss something ?

Youre right = my bad = forgot to pack the XML into the zip. Updated the zip in post #4. Thanks for pointing out.

 

[giggetto71]

thanks, but I guess I need some more help...
I have tried several combination of pins but I still get NaN from the ReadCelsius function.

Temperature=nan Celsius


the pin mapping that I am trying with the Wemos R1 Mini is the following:

SCK pin -> D5 (GPIO 14 / SCLK)
CS pin -> D8 (GPIO 15 / CS)
SO pin -> D6 (GPIO 12/ MISO)

I am assuming that the library needs the GPIO number so I am using 14,15,12.
Any clue?

 

[rwblinn]

Tested on a WeMOS D1 Mini:

MAX6675 = WeMOS D1 Mini
GND = GND
VCC = 5v
SCK = Pin D5 (GPIO14)
CS  = Pin D6 (GPIO12)
SO  = Pin D7 (GPIO13)
Thermosensor: RED = +, BLUE = -

Sub Process_Globals
    Public serialLine As Serial
    Private maxx As MAX6675
    Private PINSCK As Byte    = 14    'GPIO14 = Pin D5 
    Private PINCS As Byte    = 12    'GPIO12 = Pin D6
    Private PINSO As Byte    = 13    'GPIO13 = Pin D7
    Private timerRead As Timer
    Private READ_INTERVAL As ULong = 5000
End Sub

Private Sub AppStart
    serialLine.Initialize(115200)
    maxx.Initialize(PINSCK, PINCS, PINSO)
    timerRead.Initialize("TimerRead_Tick", READ_INTERVAL)
    timerRead.Enabled = True
    TimerRead_Tick
End Sub

Sub TimerRead_Tick

    Log("Temperature=", NumberFormat(maxx.ReadCelsius, 0, 1), " Celsius")
End Sub

 

[giggetto71]

Ok. I just found an issue with the ground pin badly soldered. Most probably i was not powering the max6675 board..later i will try again. Thank you very much for testing with the wemos. Appreciate it.

 

[giggetto71]

just tested with the ground pin properly soldered...
it works just fine!
thanks!!!!