Temperature Data logger AXE110 + NET ?

[tparvais]

Hello,

I was searching a good data logger for 8 T° probes. I think that AXE110+extension boards (RAM+LCD+Clock) is the best solution ever !

I'd like to know if we can plug to this data logger board the net board for a network access ? This will be ideal to download data to PC's and propose data on Web server. Will it require some specific developments ?

Thank you

Thomas

 

[Technical]

Moved your thread to the correct forum...

You could link the AXE110 to the PICAXE net, but you may not need to.

You can connect a temp sensor directly to the net board if required. Alternately it may be easier to use a 28X / X1 chip, as the net is designed to interface directly to the AXE022 28 pin project board.

 

[tparvais]

datalogger T° with PICAXE NET

Moved your thread to the correct forum...

You could link the AXE110 to the PICAXE net, but you may not need to.

You can connect a temp sensor directly to the net board if required. Alternately it may be easier to use a 28X / X1 chip, as the net is designed to interface directly to the AXE022 28 pin project board.

Hello,

Thank you for your fast reply. I choose AXE110 as there are wizards to generate adhoc basic code automatically, without having to study in details the PICAXE structure. I'm able to do it, but I have not the time to do it.

I'll be very happy to have your advises for my needs: record each our 7-8 tempreature probes during few months, able to load them to my pc or better to show them in HTML format. Without too many coding and soldering...

Thank you

Thomas

 

[BeanieBots]

Actually, your project is little tricky if you want to use a ready made board.
The AXE110 won't be able to read 8 sensors without a fair amount of external hardware but it does have the clock.
The AXE020 could read 8 sensors but no clock.
As for the wizard, to be honest, by the time you've understood it enough to modify it for your needs, you could probably have written it from scratch anyway. The code it produces will port to any PICAXE that has the required hardware attached. eg 28X/1.
If I wanted to "lash" something up quickly, I'd go for the AXE022. It can take a 28X/1, has download circuit/socket, EEPROM socket and a very modest set of solderable pads where you could "botch" the remaining components on.
For a little extra effort, strip board would be your best bet.
Another option might be the AXE020 but you would still need to build a circuit to add the clock, EEPROM and interface connections to the sensors.

 

[tparvais]

Of course I plan to use 2 AXE110 to support 8 probes. First one for my solar heat system and the second one for my ground-air exchanger/HVAC.

This is just a question of time... to build from scratch.
I'm totally new with PICAXE and my last µP at Unniversity usage was 13 years ago...

Are there "wizards" to help me with NET AXE022 kit ?

Thank you, I'll look at this also

 

[craigcurtin]

AXE110 as a starter

Whilst it is not cheap i would recommend the AXE110 kit as a good starting point. The basic wizard code will give you an idea of how to get started with what you want to do and you can upgrade the EEPROM to a 24LC256 with only a minor cost.

This was how i first started out and then moved to some custom made boards for a 40X1

My system now controls my solar heating/boiler/hydronic heating system for the entire house - next stage is to move to multizone control and an external Waste Oil furnace to supplement/replace the Natural gas boiler.

The issue you will have with the AXE110 is the limited number of available I/O lines.

I removed the onboard LED and used the two outputs to control a couple of relays, i also used some offboard resistors to give me 3 DS18B20 temp probes.

regards

Craig

 

[tparvais]

That's very interesting. This is indeed what I want to do. I think I'll move to AXE110 first.

Twolast questions:
-I read that with PICAXE18X, only Pin7 is configured for 1-wire DS18b20 temp probe ? Does it mean that I can't connect directly 4 DS18B20 to this kit ?
-The Temp° data saved into memory is is directly in degree with the timestamp ?

Thank you

Thomas

 

[craigcurtin]

Walk before you run

The AXE110 (and indeed the 18X) does not support the 1 Wire protocol for multiple 1wire devices (DS18B20 in your case) from the same cable run.

You will have a maximum of 4 temp sensors you can run from the 18x as mounted on the AXE110. Only one of these has the necessary 4K7 resistor onboard so you will need to ensure you place resistors on the other drops.

The READTEMP command will return whole celsius temperature degrees.

have a look at some of the wizard code in terms of writing to eeprom it is very straightforward

regards

Craig

 

[tparvais]

That's very clear. thank you. I've ordered AXE110 for tutorial and a protoboard 28X/40X for more complex experiments.

Thomas

 

[AlanT]

DS18B20 CRCs

Hello All

I'm developing a controller for a water heating system, so I'm using the Dallas temperature probes - several of them on the 1-wire bus. I'm using a 28X1 PIC as the core device.

I've written a CRC checker which seems to work as far as the Dallas addresses are concerned, and also works most of the time with the received 9-byte string from the scratchpad read. However the error rate is higher than I expected, apparently regardless of the length of the bus, or the number of sensors. In other words I've reduced the configuration to one sensor attached to the end of the ribbon cable supplied with the project board, and it still gives errors.

To see whether the problem is on the TX or RX side, I check the 5th byte received, the status byte, as it is a known value, and it gives 100% OK, showing that the Dallas received the read command and has transmitted a valid reply. But the CRC check fails between 10 and 90% of the time.

I've tried playing around with the value of pullup on the 1-wire, and also played around with the software timing for the interface, but nothing seems to make a difference.

Does anyone know of problems with the CRC from the Dallas, or is there anything regarding the electricals on the 1-wire that isn't shown in the application notes ? Does anyone have a "reference" CRC routine ?

All ideas appreciated

Cheers

 

[lbenson]

Here is a link to the phanderson site which "Illustrates how to calculate the 8-bit Cyclic Redundancy Check (CRC) of data received from Dallas 1-W devices."

http://www.phanderson.com/bx24/crc.html

It isn't in picaxe basic, so conversion would be needed. You can also search the forum for "CRC*"--the asterisk is needed because strings of less than 4 characters are not found.

This link has code. Unfortunately, code in the old forum style hasn't been converted properly to the new style, so it also must be cleaned up.

http://www.picaxeforum.co.uk/archive/index.php/t-693.html