Sorry to hear about your accident Robin, I hope you continue to make a good recovery! I assume that you have discovered the arduino forum? There’s a lot there about such projects though some dross filtering is needed! Lots of code posted on github too.  But you could also look at the Raspberry Pi ecosystem, the Pi Pico is much more capable than most arduinos, can be programed in C or Python, and there’s loads of code available.

I believe ESPs also have proper security features should that be important.

You can communicate twixt Arduino and mobile phone by blue tooth, so I’d be surprised if you couldn’t talk to a PC that way. Just a possible alternative

There’s a book to be written comparing the pros and cons of the various microcontrollers available.

Briefly:

• Arduino’s are beginner friendly, electrically robust, and extremely well supported with software libraries and plug in modules.  Strong on General Purpose IO, and OK for protocols like I2C and SPI etc.  They are relatively slow, don’t have much memory, and have to be programmed in C (actually sawn-off C++).   C would be a serious obstacle were it not for the Arduino IDE which does an extraordinarily good job of hiding the complexity of the underlying tool-chain.
• Though improving, Picos are less well supported than Arduinos.   They’re inexpensive, have two fast processors, plenty of memory and some interesting peripherals.  Pico W and Pico WH have built-in Wireless Ethernet and Bluetooth, bit fewer IO pins.  Pico are programmed in either C/C++ or MicroPython.    The latter is beginner friendly, but C/C++ is proper grown-up.   A simplified C/C++ environment is available for the Arduino IDE, but don’t expect Arduino libraries to ‘just work’ on a Pico.   Easier to learn and write MicroPython than C/C++. but the result will execute relatively slowly and consume more memory.   Performance probably not a problem in Robin’s application.
• ESPs are fast processors, with built-in wifi.  Not got into them in detail, but fairly well supported.   Main disadvantage is the smallish number of IO pins available.
• STM Nucleo are another option, fast processors, loads of pins, several boards.  Mostly programmed in C/C++,  and on the grown-up side rather than beginner friendly.

When choosing one, it’s important to consider how easy it will be to program.   Very often microcontrollers are connected to a peripheral, and the last thing a beginner needs is to find he has to write the interface code himself!  Interfacing to an unsupported peripheral is not beginner  work!  Far better to use a microcontroller for which a documented library already exists, ideally supported with tutorials and forum info.  This is where Arduino generally has an advantage.

That said, this Pico example isn’t a million miles away from Robin’s requirement.

Dave

On 11 August 2024 at 10:01 duncan webster 1 Said:

On 11 August 2024 at 07:53 John Haine Said…………. The Nano is probably easier to use (at first) and only has 3.3V I/O.  I’ve been using Arduino exclusively but future projects will definitely use the Pi.

The ones I’ve been using have 5v I/O, admittedly clones, and they cost a lot less than £22

Sorry, I meant 3v3 for the Pico.  Yes, I always use Nano clones too, I was just comparing the official prices of the two products.

On 13 August 2024 at 00:21 Robin Graham Said:
[…]

I hope it’s obvious but before anyone tells me to just buy a b****y fridge, this is more journey than destination!

It is indeed obvious, Robin … and I wish you a good journey.

MichaelG.

I’m glad you’re making progress Robin.  And thanks for the link to Lief’s blog – it looks very useful.

Robin,

A very quick way of doing this is to use Node-Red –  a free install on PC and Linux, which is a graphical programming tool. There are thousands of user written ‘nodes’ which you can download and use to create the flow diagram for your application. You then place display nodes ( gauges, graphs, bar charts, etc) on a display page, and the data is displayed as you want. You don’t need to know C, Python, Cobra, or any language if you don’t want to, although Java script can be useful but I don’t need it..My house automation, solar system, weather station, underfloor heating and Alarm is all controlled via node red. I use ESP32’s all over – they link via wifi, using Mosqitto as an MQTT server, running on the same pc as the node red. Coms tween esp32 and node red is very easy and there are dozens of open source nodes out there to do anything you could want. Very powerful and very simple.

This is a sample image of the display page of the weather station – also shows the status of the lights in the house – they are automated to turn on/off randomly at night when away, etc

This shows the node red nodes that implements the display page above

Of course you have to write the code for the esp32 itself, and I do that all in the Arduino IDE using the esp32 extensions – easy as pie ( NOT PI)

On 26 August 2024 at 09:36 John Haine Said:

Just to add, I found this yesterday:

https://randomnerdtutorials.com/programming-raspberry-pi-pico-w-arduino-ide/#Raspberry-Pi-Pico-Boards-Manager

I have just followed the procedure there to install the Pico 2040 to the Arduino IDE and it was trivial.  Not tried programming yet but looks promising.  Being pretty familiar now with the Arduino this looks a good way forward.

When the Pico2040 first hit the streets, the Arduino IDE had almost no libraries for the Pico.   If a programmer wanted to use a DS18B20 temperature sensor, he had to write code implementing the OneWire interface and the Dallas Temperature protocol.   The compiler fully supports the programming needed, but implementing low-level system functions from the datasheets is hard work.  Easier to find an existing library implementation for a similar chip and modify it.  I was going to recommend the mbed and ESP libraries as a start.  Still hard work.

Good news is that a large number of Pico libraries have become available for the Arduino IDE since the last time I looked.   For Robin’s application, I recommend the DS18B20 sensor because it covers the necessary fridge temperature range with good accuracy and an encapsulated version is available.

Haven’t been able to get Pico to read a DS18B20 yet!

Dave

On 30 August 2024 at 01:02 Robin Graham Said:

…

At some point I think I lit on the possibility of using the Arduino IDE to program the pico, but I’ve gone off on so many tangents with all this that it got lost.

The advantage of the Arduino IDE is that it’s specifically designed to simplify programming microcontrollers.  A lot of difficult detail is hidden behind the scenes, allowing programmers to concentrate on writing code, not spending days setting the environment up.

I revisited the Arduino IDE and did indeed see ‘Arduino Mbed OS RP2040 Boards -> Raspberry Pi Pico’ in the ‘Board’ menu.  I tried with ‘Blink’ which seemed to compile / build OK, but gave an unhelpful ‘Error Uploading’ message.

The upload failed because the Pico wasn’t in BOOTSEL mode.   Most boards programmed by the Arduino-IDE switch automatically into upload mode, but despite claims it should after first connect, I find my RP2040 doesn’t.   It’s important to get this right, Adafruit’s instructions has a little video!

 

I then installed the RP2040 package from Earle Philhower and all went well.  So, focusing on the Pico route possibilities seem to be:

• Arduino IDE + the EarlePhilhower RP2040 board package.  If the various Arduino libraries for specific peripherals work this looks to be the easiest way forward.  Dave’s result with the DS18B20 is encouraging.

I’d rather stick with the Arduino teams standard package.   Could be wrong, but I think it’s better supported in terms of advice and libraries.   Low risk – if EarlePhilhower lets you down, not difficult to go back.

• RP’s own Pico SDK.  This allows building executables from source using the command line.  The SDK provides scripts for processing source using both CMake and Bazel which are industrial strength tools designed to allow compiling/linking code written in a variety of languages for a variety of target platforms. So necessarily complex.   Not trivial to get to grips with (for me at least), but allows direct access to the comprehensive SDK.

Extremely complex.  The Arduino-IDE is designed to be beginner friendly, and it’s a good learner platform.  The Pico-SDK does much more than the Arduino-IDE but the beast isn’t intended for beginners!

• Various IDE tools (eg VScode, as recommended by RRi).  These are GUI ‘wrappers’ for CMake &c so far as I can make out. I had zero success with them despite spending quite a lot time trying. In the link I gave earlier Lief Koepsel says: … If you develop code for living, by all means, use the tool of professionals, an IDE. If you are experminting/learning/hacking, focus on the project not learning how to use an IDE.“

That’s good advice.  Professional programmers don’t like the Arduino-IDE much because it doesn’t let them change what goes on behind the scenes.   Though it might matter to a pro which ‘make’ tool is used, the average Joe is unlikely to care.

…

Dave: I actually have a DS18B20 which I got working fine with a Nano and the DallasTemperature library. It’s impressive for such a cheap device. I got 0.3-0.4 C in an ice/water bath which gave 0-0.2 C using a PT100 resistance probe.  Good to hear you got it going with the Pico. I was planning to use PT100s which work well with the Adafruit MAX31865 board, but not with the cheap (<£5) clones which were up to 2C out when they worked at all.  These all use SPI – I’d be interested to hear of any results using SPI on the Pico.

There is a Pico library in the Arduino Library Manager that supports the PT100, called RAK12022-MAX31865.   Details on github here.   SPI should work on the pico – there’s a standard library – #include <SPI.h>

Robin.

Further to my DS18B20 experiment, I connected three sensors in parallel to see if the library detects that automatically.  It does.  DS18B20 sensors have a unique address, that the library presumably detects by scanning the bus when the program starts.   The example program prints results like this:

The program identifies particular sensors by ‘deviceIndex’.

Oh, and Mark’s warning about fakes might explain why my device 2 consistently reads a degree low!  Hmmm…

Dave