Code examples for One-Wire library use for multiple ds18b20 sensors?

Device Code
1

Hi everyone,

After getting my temp logger up and running with TMP35 analog sensors, I’d like to upgrade to using the ds18b20 sensors. I’d like to use the supplied One-Wire library, but all the code examples I can find are pre-library (including this one: https://electricimp.com/docs/resources/onewire/).

So as a noob, if anyone has a code resource that I could be forwarded that outlines the One-Wire library use on multiple sensors, I’d be grateful. I’ll need 3 sensors on my setup.

Thanks.

2

You could try the 1-Wire library accessible via the IDE: https://electricimp.com/docs/libraries/hardware/onewire.1.0.1/

3

Here’s what I use:

`ow<-Onewire(hardware.uart12); ow.init()
local dcount=ow.getDeviceCount(); local devices=ow.getDevices()

function DS18B20(device) {
ow.reset(); ow.matchRom(); for (local i=7; i>=0; i-- ) {ow.writeByte(device[i]); }
ow.writeByte(0x44); imp.sleep(0.8)
ow.reset(); ow.matchRom(); for (local i=7; i>=0; i-- ) {ow.writeByte(device[i]); }
ow.writeByte(0xBE); 
local tempLSB=ow.readByte(); local tempMSB=ow.readByte() 
local tempCelsius=((tempMSB*256)+tempLSB)/16.0  ;
return tempCelsius      }`

Then call each DS18B20 like this:

newTemp[0]=DS18B20(devices[0]); newTemp[1]=DS18B20(devices[1])

Works like a charm for my two devices, but should work for any number, I would think.

4

Hey thanks Rfarmer. Although I have had numerous read throughs the onewire library documentation, I had been struggling to conceptualise how to put it into practice. Your chunk of code helps! My sensors will arrive this week and I look forward to giving it a go.

Thanks again!