Hi
I've created a display showing 6x thermocouple temp, found something to i2c, that I should not run 10 wires to the 6 thermocouple?
I've looked on the net, do not think I can find something with both inputs or outputs.
only thing i found whas the MCP23017 chip. i was looking for a simpel bord.
This is the thermocupler's
/Bruno, Denmark
I'm sorry, it's not clear what you are asking here.
What does I2C have to do with this? The board uses SPI. You should be able to put all 6 on the same data lines, and just run a separate CS line to each one...
If you are looking to reduce the number of Arduino pins used for chip selects, check out the 74HC138. It uses 3 Arduino pins to select 1 of 8 outputs (chip selects).
DrAzzy:
I'm sorry, it's not clear what you are asking here.What does I2C have to do with this? The board uses SPI. You should be able to put all 6 on the same data lines, and just run a separate CS line to each one...
I would like to run as little wires from Arduino to the box with 6 thermocouple.
so I thought we could get a i2c bord that provides more I/O that I could put in the box with thermocouple.
groundfungus:
If you are looking to reduce the number of Arduino pins used for chip selects, check out the 74HC138. It uses 3 Arduino pins to select 1 of 8 outputs (chip selects).
I was hoping you could get something like a finished bord, so I'm not even going to make a print.
multiple TC board
Like this?
it is nice if arduinoen is located where the sensors are mounted, but it is not possible in my case.
You could use a number of different shift registers (or port expanders) for this... Like, there are lots of them.
I would not use an I2C one. Use an SPI one, using the same data lines that you use for the thermocouples, and run just one line out for the latch line (the details depend on which shift register you use), so you've got the SO line of all the thermocouples tied to MISO on board, all the SCK lines tied together, and MOSI of board connected to input of shift register. That gets you down to 6 wires - Vcc, Gnd, SCK, MISO, MOSI, and the extra line to control the latching of the shift register. As I noted above, there are a bunch of shift registers and port expanders you could use.
How long is the wire going to be? SPI and I2C aren't good with long wire runs (the exact limit depends on what SCK frequency you're using, wire lengths, whether the wires are shielded, and nearby interference)
You are unlikely to find a board with just a shift register on it - manufacturers typically don't consider that worth a board - they're routinely included in breakout boards with other parts on them already connected to it (for example, the I2C backpacks used on many LCD screens). As groundfungus posted while I was writing this, there are multi-channel thermocouple boards which may be better for you - though the one he posted requires 7 wires plus supply and ground, it looks like - so whats the point?).
You can get shift registers in DIP package and use an ordinary piece of prototyping board, or get one in an SOIC package and use a common breakout board (i happen to sell some little and not-so-little pieces of prototyping board that might be helpful here - of course, other vendors have other offerings in this space as well. Obviously, mine are superior, but of course I would say that, wouldn't I?).
brunokc:
it is nice if arduinoen is located where the sensors are mounted, but it is not possible in my case.
You can use shields remote from the Arduino, by connecting wires to the pins on the shield and running back to the arduino. As I noted, the one he linked above requires kind of a lot of wires)
What is the distance between the Arduino and any interface board you use?
I thought I would use IC2 because I thought that I could come down to 4 wires, and I already use i2c lcd screen
is 100cm between the two things.
That multiple TC board muxes thermocouple signals. That is not only noisy but getting an accurate reading via a 50 ohm on resistance of the FET (In the mux chip) is next to impossible unless the op amp compensates for that. I am working with a MAX6675 and muxing that seems to not be feasible.