MAX6675 support

[node-alpha]

Added MAX6675 support -- Tested on Raspberry Pi (model B).

[abc2006]

After a couple of whiles i got it running on a RPI3ModelBVer1.2:
connect
SCK: PIN 23 SPI_CLK GPIO11
CS: to PIN 24 SPI_CE0_N GPIO8
S0: to PIN 21 SPI_MISO GPIO9
VCC: to PIN 1
GND: to PIN 6

Use following Program:
#!/usr/bin/python
from max6675 import MAX6675, MAX6675Error
import time

cs_pin = 8
clock_pin = 11
data_pin = 9
units = "c"
thermocouple = MAX6675(cs_pin, clock_pin, data_pin, units)
running = True
while(running):
try:
try:
tc = thermocouple.get()
print("tc: {}".format(tc))
except MAX6675Error as e:
tc = "Error: "+ e.value
running = False
print("tc: {}".format(tc))
time.sleep(1)
except KeyboardInterrupt:
running = False
thermocouple.cleanup()

Thanks Draco for your Work!

Greetings, Stephan

[henrique-rsilva]

Hello guys, @node-alpha @Tuckie @abc2006 @dlleigh

Look, there is a short script in the link:

https://github.com/Tuckie/max31855/pull/4/files

Which is the sample in the documentation for max6675:

---

MAX6675 example
#!/usr/bin/python
from max6675 import MAX6675, MAX6675Error

cs_pin = 24
clock_pin = 23
data_pin = 22
units = "c"
thermocouple = MAX6675(cs_pin, clock_pin, data_pin, units)
print(thermocouple.get())
thermocouple.cleanup()

---

This snippet of code above doesn't work, at least, for RPi 3 B v1.2

See:

There are two ways of adress pins in the Raspberry Pi.

GPIO.Board -> references the physical numbering of the pins
GPIO.BCM -> is the Broadcom Soc Channel numbering (eg.: GPIO04 .....)

In the library max6675.py implementation, you need to pass the BCM pins.

The code below works well to me at Rapberry Pi 3B (Thanks @abc2006, your tip helped a lot).

---

#!/usr/bin/python
from max6675 import MAX6675, MAX6675Error
import time

cs_pin = 8
clock_pin = 11
data_pin = 9
units = "c"

thermocouple = MAX6675(cs_pin, clock_pin, data_pin, units)
running = True

while(running):
try:
try:
tc = thermocouple.get()
print("tc: {}".format(tc))
time.sleep(1)
except MAX6675Error as e:
tc = "Error: "+ e.value
running = False
print("tc: {}".format(tc))
time.sleep(2)
except KeyboardInterrupt:
running = False
print("\nStopped by User\n")
thermocouple.cleanup()

---

@node-alpha , to make the life easier, i'd suggest:

In this part:

Initialize needed GPIO
GPIO.setmode(self.board)
GPIO.setup(self.cs_pin, GPIO.OUT)
GPIO.setup(self.clock_pin, GPIO.OUT)
GPIO.setup(self.data_pin, GPIO.IN)

Please, change this name --> GPIO.setmode(self.board)

This causes a lot of confusion, because you did in the init:

==> board = GPIO.BCM

It's not cool to keep like that.

Because you put together two ways to adress pins at RPi.
And this mixture is confusing the way you did.

I hope it helps.

Thank you very much for your work.

Regards,

Henrique

[nilu0007]

Can we measure negative Temperature