I put together rpi-temperature-monitoring to solve exactly this. It reads CPU, GPU, and SSD/NVMe temperatures (via smartctl), stores everything in a local SQLite database, and serves a dashboard with interactive charts from a built-in Python web server. The whole thing runs on Python standard library only, no external dependencies. You get a web UI with Chart.js graphs showing 1-hour to 1-week views, auto-refreshing every 30 seconds. It also supports external sensors like DS18B20 or DHT11/DHT22 through a plugin system if you want to go further.

Pure Python, SQLite and a single setup.sh to get it running with systemd services. The SSD monitoring works with NVMe and SATA devices and even stores the device model name so you can tell which drive is which. If you run a Pi as a home server or a node for something and want a simple way to check if your SSD is overheating, this does the job without pulling in half the internet as dependencies.

Setup SD card according to https://roboticsbackend.com/enable-ssh-on-raspberry-pi-raspbian/, enable SSH, setup wifi and setup main user password.

Copy data from SSD to SD card, like wallet. Mount SSD acoording to https://linuxhint.com/mount_usb_drive_debian/ and copy /home/<user>/.hydra directory to SD card. If the blockchain history is too big, copy only .hydra/wallet folder with your wallet.

When making the bit copy of SD card back to SSD, it is still great to use https://github.com/billw2/rpi-clone and follow paragraph 4 with command

rpi-clone -l sda

I bought Rpi4 with maximum RAM and with 1TB SSD as originally I wanted to play with BTC full node and LN. But I diverged my plan after a while to Hydra as it promised around 70% APY reward. I am going to share what steps I took to setup Rpi and the wallet as it wasn’t straight forward.

Rpi4 setup

Imagine you buy Rpi, have some microSD card and want to run Linux from SSD as your goal is to run full BTC node. Where to start? Great start is to prepare SD card and put Raspberry Pi OS on it (https://projects.raspberrypi.org/en/projects/raspberry-pi-setting-up/2). As I don’t have external keyboard nor microHDMI cable I wanted to set everything via SSH. For that you need to enable SSH on first boot, the post (https://www.raspberrypi.org/documentation/computers/remote-access.html) is straight forward, you need to create file with ssh name in boot partition. Same page also helps with finding what is the IP address associated with Rpi when you connect it to computer via cable. I used arp -a command to list all interfaces and associated address on my MacOS. As I allowed to share internet I was searching for bridges and one of them had IP address 192.168.2.2. Then connection is easy: ssh pi@192.168.2.2.

Now you are connected to Rpi which starts from SD card, how to configure it to start from SSD without SD card? (https://peyanski.com/how-to-boot-raspberry-pi-4-from-ssd/) or (https://www.maxinoha.cz/raspberry-pi-4-boot-z-ssd/) articles shows how to copy system from SD card to SSD and enable boot from SSD, but the copy tool is GUI application. How to copy that from console and e.g. expand partition? I used rpi-clone console application which is pretty straight forward to use (https://github.com/billw2/rpi-clone).

Building Hydra wallet

As we installed RPI OS, which is 64bit system we are gonna hit first issue, wallet deamon woudn't run when unpacking the downloaded 64bit Hydra release:

./hydrad
-bash: ./hydrad: cannot execute binary file: Exec format error

So continue with manual installation on Ubuntu: (https://github.com/Hydra-Chain/node):

sudo apt-get install build-essential libtool autotools-dev automake pkg-config libssl-dev libevent-dev bsdmainutils git cmake libboost-all-dev libgmp3-dev

sudo apt-get install software-properties-common

We cannot add bitcoin repository as it is obsolete, but it is added only to have Berkley DB binaries. We need to build libdb4.8 on our own from source. All details can be found in this answer (https://askubuntu.com/a/976624).

$ wget 'http://download.oracle.com/berkeley-db/db-4.8.30.NC.tar.gz'
$ tar -xzvf db-4.8.30.NC.tar.gz
$ cd db-4.8.30.NC/build_unix/
$ ../dist/configure --enable-cxx
$ make
$ sudo make install

Tell your system where to find db4.8:

$ export BDB_INCLUDE_PATH="/usr/local/BerkeleyDB.4.8/include"
$ export BDB_LIB_PATH="/usr/local/BerkeleyDB.4.8/lib"
$ sudo ln -s /usr/local/BerkeleyDB.4.8/lib/libdb-4.8.so /usr/lib/libdb-4.8.so
$ sudo ln -s /usr/local/BerkeleyDB.4.8/lib/libdb_cxx-4.8.so /usr/lib/libdb_cxx-4.8.so
$ sudo ldconfig

After that you can continue with compilation of Hydra

$ ./autogen.sh
$ configure  CPPFLAGS="-I/usr/local/BerkeleyDB.4.8/include -O2" LDFLAGS="-L/usr/local/BerkeleyDB.4.8/lib"
$ make -j2

See we did tell configure where the libraries are. More details here: (https://vhernando.github.io/bitcoin-core-node-build-sources-debian)

After that we should also set LD_LIBRARY_PATH this way:

$ export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/lib/libdb-4.8.so

And we are ready to run daemon to sync the chain history on the machine. Try to run from src folder

$ hydrad

Voala, it works. So now it is time to import your keys (https://docs.hydrachain.org/hydra-for-beginners#importing-your-key-using-the-cli-in-linux) or setup fresh wallet. After that you can start daemon to run on background:

hydrad -daemon

Solving issues

Once RPi wasn't reachable via SSH with error: kex_exchange_identification: read: Connection reset by peer. After restart I was checking /var/log/auth.log for any clues why sshd disconnected (https://raspberrypi.stackexchange.com/a/111734). I dug up the syslog with the

tail -f -n X /var/log/syslog

command (where X  is number of lines you want to display. I then noticed few lines mentioning a Voltage problem (sorry I did keep the exact terms).

Another fancy issue is when you want to connect old monitor with DVI-HDMI adapter. It could or couldn't work. Fix is easy. Either use raspi-config or edit /boot/config.txt and enable hdmi_force_hotplug=1.

Nowadays it is much simpler to start with Ghost 2.x on Azure as there are lot of tutorials. According to this blog: https://www.gatevnotes.com/introducing-ghost-2-on-azure-web-app-service/ you can install Ghost by one click.

Now your blog is running on https://{something}.azurewebsites.net which is great for testing but you would like your own domain, right :) You can buy your own at your domain registrar or through Azure portal. In this tutorial is simply explained how to map your domain to App Service powering your blog: https://docs.microsoft.com/en-us/azure/app-service/app-service-web-tutorial-custom-domain.

Now you have domain, but browser would complain about certificate as it is still using certificate for azurewebsites.net domain. Nowadays you can have free certificate from Let's Encrypt and it is quite easy to deploy it in Azure. Follow this blog post: https://gooroo.io/GoorooTHINK/Article/16420/Lets-Encrypt-Azure-Web-Apps-the-Free-and-Easy-Way/21872. As it is bit dated there are two changes. Instead of:

$password = '{some strong password}'

you should create secure string:

$password = ConvertTo-SecureString '{some strong password}' -AsPlainText -Force

When finished with tutorial, blog should run on new domain with new certificate. What you need is to ensure that there is nowhere used old azurewebsites.net links. Go to in Ghost admin and on Design tab change all navigation links to your new domain. In Azure portal change App Setting called url to new domain. That would be it.

Certificate renewal

In the GooRoo article is section 5 about certificate renewal. You should check the WebJob being created and running. In my case I saw warning about Cron:

To setup Always on, go to App Settings -> General Settings and there you can find a knob Always on:

That's it.

P.S.: The password for Let's Encrypt application will expire in one year. I expect you would be interested in renewal. Please read https://blog.rassie.dk/2019/08/update-azure-active-directory-service-principal-credentials/ and store generated password in letsencrypt:ClientSecret application setting.

P.S.2: 1.0.5+ Let's Encrypt extension application require two new connection strings: 1.0.5 DashboardConnectionString and StorageConnectionString not documented · Issue #354 · sjkp/letsencrypt-siteextension · GitHub. When you are running this app, just copy paste the storage account string into the two fields and check the checkbox under them (Update Application Settings and Virtual Directory).

P.S.3: Azure team is working on free certificates, see: Secure your Custom Domains at no cost with App Service Managed Certificates (preview) | Azure updates | Microsoft Azure

Chip only

If you have a chip only without any board you would have a programmer to burn your code in. The most easy way is to use your Arduino UNO board:

Where these pins are connected:

• ATtiny Pin 1 to Arduino Pin 10
• ATtiny Pin 5 to Arduino Pin 11
• ATtiny Pin 6 to Arduino Pin 12
• ATtiny Pin 7 to Arduino Pin 13

The capacitor between ground and RESET is 10µF.

or Leonardo:

Burning program to ATtiny 85

First upload the ArduinoISP example code to your Arduino. Dont't connect the capacitor and ATtiny yet.

Preparing Arduino IDE for ATtiny 85

You must have Arduino IDE version >= 1.6.4 to be able add another board layouts. Then you can in preferences dialog add a new URLs in Additional Boards Manager URLs. These URLs are comma separated list. For ATtiny you can use https://raw.githubusercontent.com/damellis/attiny/ide-1.6.x-boards-manager/packagedamellisattinyindex.json or http://digistump.com/packagedigistump_index.json for Digispark ATtiny boards with USB (see bellow).

Open Boards Manager in Board menu and pick ATtiny to install.

Next step is to connect the capacitor and ATtiny. Open Blink example code and change pin from 13 to 3.

• Select ATtiny
• Select 1MHz
• Leave serial port as is
• Select Tools -> Programmer -> Arduino as ISP
• Connecting LED with resistor to pin 2 => would blink.

From http://www.ernstc.dk/arduino/attiny85.html.

Board with USB

These boards are easier to program but don't expect classic USB port.

Next time we will focus on:

• USB-k drivers
• Windows 10 vs Mac
• setup ARduino IDE
• micronucleus
• example of volume knob

They wrote it is working in 900 / 1800 MHz networks (compared to 850 / 900 / 1800 / 1900 MHz for SIM900) which is what we use here in Europe. What I missed was information that it is locked to these regions: China, India, Singapore, Malaysia, Thailand, Indonesia, Cambodia, Vietnam, Laos, Burma, Brunei, Philippines and East Timor. Thanks to Per Jensen's blog post about that.

I thought I have a brick but fortunatelly there were rummors about flashing SIM900 firmware to remove country lock.

Communicating with SIM900A Mini module

This module provide two ways how to communicate: RS232 and TTL level pins. I got in package also TTL to USB level convertor with CP2102 chipset.

RS232

RS232 interface is placed under SIM Card slot and it's pins are named by pins to connect to in DB-9 connector:

• DB9-2 to 2nd pin
• DB9-3 to 3rd pin
• GND to 5th pin

I started with this connector because it was clearly described how to connect to this port and I had also Serial - USB cable. Problem was that flashing software wasn't able to flash firmware. I am suspitious that it was because MAX232 convertor.

TTL

I wasn't sure how to connect delivered convertor to the board because seller description was ambiguous because he provided this table

and description:

Use the TTL interface connect with a MCU

MCU -> SIM900A MOULE TXD -> 5VR
RXD -> 5VT
GND GND

Notice that:

1. The pin of VCC_MCU is used for compatible the TTL interface. When the high level of the MCU is 5v like the 51 MCU, we should connect the DC5V to VCC_MCU, when controller is 3.3V like the stm32 MCU, the VCC_MCU should connect the DC3.3V.
2. The 3VR 3VT pins are reserved for future.

Problem was that the board has pins described below and connection as mentioned above didn't work.

So what to connect where? On one page I found some info about flahsing but what was more important also a image how to connect the TTL convertor.

My setup was:

Finaly I was able to connect to it:

>AT
OK

Important is to use as first command capital letters because they are used by module to determine a communication speed.

Firmware flashing

We need two pieces, firmware and flasher. You can download flasher from page Geekonfire.com, see step 1.

You need also firmware. There is page of Dost Shah where he collects all available firmwares.

How to pick a right firmware? Fist run command

>at+cgmr
Revision:1137B01SIM900A64_ST_MMS
OK

to know which firmware you have in. Most important is that there is SIM900A firmware and it's size is 64bit. If you have in only 32bit you are doomed because all SIM900 firmwares are 64bit.

Regarding page http://amichalec.net/2014/08/sim900a-fixed-for-europe/ you can follow these steps:

1. Power up your SIM900A module to respond to AT commands in auto-baud mode (AT+IPR=0).
2. Setup flashing tool — connect it to SIM900A, set default speed of 460800 baud, choose firmware to flash from unpacked RAR file, select “don’t check file name” check-box and press “start download” button to see “Power On/Reset Target” message.
3. Short NRESET (pin 16) to GND for a moment. Right after it reboots flashing tool will start pushing data.
4. When flashing ends with “Download complete” power off SIM900A module. Note that reset will not work, disconnect power line and start power-on sequence once again.

Step 3 means that you can put jump wire to RST hole and for a fraction of second to short it to GND. See instrctables.com but no soldering is needed.

After flashing and restart at+cgmr command can show you that there is SIM900 firmware loaded in.

Testing basic functionality

When you have everything prepared you can try to use online Java applet to test your modem.

If you don't want to run Java applet you can try to send SMS which is quite simple:

>AT+CMGF=1                   // sending in text format
at+cmgs="+xxxxxxxxx"         // phone number 

text of SMS 

1A                           // CTRL+Z in HEX format 

Done. I would like to warn you that these steps worked for me and your conditions could be different and you must find your own solution. I am not responsible for what you are doing and if you bricked or burned your device.