Architecting a multi-sensor project

General
#1

Hi All

I recently prototyped a single thermocouple with the Electric imp and all went very well. I now want to put together a project using (1) Electric Imp, (1) 4-channel I2C-safe Bi-directional Logic Level Converter, (18) MAX31850K & (18) k-type thermocouples.

Assumptions:
a) It’s my understanding that this would be considered a “1 wire” architecture. Is this true?
b) Can (1) 4 channel logic converter be used for all 18 or will i need 5?
c) As i install each MAX w/ thermocouple, it will have its own unique id and after I receive this “id”, i should save it as a const. I should do this individually until i have each id cataloged. After, I can then add all sensors to my board and enable the entire system. Is this the approach i should take?
d) Should I reconsider and use another platform? I’m looking for this prototype to be a spring board into a production ready solution w/ minor deviations from the prototype.

For any that respond, thank you.
Chris

#2

I don’t believe you need any logic level converters; the MAX31850K runs at 3.3v anyway. You will need the 1 wire interface setup though (resistor & diode, see https://electricimp.com/docs/resources/onewire/

Depending on how long your bus is, you may want to consider using an I2C-to-1wire bridge chip eg http://datasheets.maximintegrated.com/en/ds/DS2482-100.pdf - when the bus capacitance gets high, you need an active pull-up for the bus to work.

The imp platform will work well for this, and you can transition very easily to production - you may want to start using an imp002 or imp003 though, vs an imp001, but that depends on how many you want to make (the imp001 isn’t made any more, though there are a number of thousand left in stock).