First steps with Fedora IoT on Raspberry Pi 4

This is just a quick description, brain dump, of how we started measuring temperature and moisture in various rooms in our flat. This first part describes setting up a server that will collect and present the data.

Here I was basically just following How to install Fedora IoT on Raspberry Pi 4 post.

First, I installed prerequisites on my Fedora workstation:

$ sudo dnf install gnupg2 arm-image-installer

Now download images and Fedora GPG key so I can verify the signature of the downloaded image:

$ wget https://download.fedoraproject.org/pub/alt/iot/39/IoT/aarch64/images/Fedora-IoT-39.20231103.1-20231103.1.aarch64.raw.xz
$ wget https://download.fedoraproject.org/pub/alt/iot/39/IoT/aarch64/images/Fedora-IoT-39-aarch64-20231103.1-CHECKSUM
$ wget https://fedoraproject.org/fedora.gpg

Now verify the signature and check the downloaded key fingerprint matches what Fedora team publishes on a page with list of current GPG keys fingerprints.

$ gpgv --keyring ./fedora.gpg Fedora-IoT-39-aarch64-20231103.1-CHECKSUM
gpgv: Signature made Mon 06 Nov 2023 03:03:23 PM CET
gpgv:                using RSA key E8F23996F23218640CB44CBE75CF5AC418B8E74C
gpgv: Good signature from "Fedora (39) <fedora-39-primary@fedoraproject.org>"

$ gpg --show-keys fedora.gpg | grep -C 1 E8F23996F23218640CB44CBE75CF5AC418B8E74C
pub   rsa4096 2022-08-09 [SCE]
      E8F23996F23218640CB44CBE75CF5AC418B8E74C
uid                      Fedora (39) <fedora-39-primary@fedoraproject.org>

Also check checksum of downloaded image:

$ sha256sum -c Fedora-IoT-39-aarch64-20231103.1-CHECKSUM
Fedora-IoT-39.20231103.1-20231103.1.aarch64.raw.xz: OK
sha256sum: WARNING: 17 lines are improperly formatted

I guess that warning in the output is there because the checksum file also contains GPG signature and sha256sum utility dislikes it, so I did not worried about it:

$ cat Fedora-IoT-39-aarch64-20231103.1-CHECKSUM
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

# Fedora-IoT-39.20231103.1-20231103.1.aarch64.raw.xz: 712162312 bytes
SHA256 (Fedora-IoT-39.20231103.1-20231103.1.aarch64.raw.xz) = bb10ed4469f6ac1448162503b68f84e96f8e8410e5c8c9a4a56b5406bf13dff2
-----BEGIN PGP SIGNATURE-----

iQI[...]
-----END PGP SIGNATURE-----

Now I put SD card into the USB reader and connected it. It shows nicely in lsblk output as /dev/sda:

$ lsblk
NAME                                          MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINTS
sda                                             8:0    1  29.7G  0 disk  
├─sda1                                          8:1    1   512M  0 part  
└─sda2                                          8:2    1   4.4G  0 part  
zram0                                         252:0    0     8G  0 disk  [SWAP]
nvme0n1                                       259:0    0 476.9G  0 disk  
├─nvme0n1p1                                   259:1    0     1G  0 part  /boot
├─nvme0n1p2                                   259:2    0    32G  0 part  [SWAP]
└─nvme0n1p3                                   259:3    0 443.9G  0 part  
  └─luks-c9494ef2-8c28-4817-befb-8ac43ff79ee3 253:0    0 443.9G  0 crypt /home
                                                                         /

So now I should have everything needed to write Fedora IoT image to the card:

$ sudo arm-image-installer --image Fedora-IoT-39.20231103.1-20231103.1.aarch64.raw.xz --media /dev/sda --addkey /home/jhutar/.ssh/id_rsa.pub --norootpass --resizefs --target=rpi4 -y
[sudo] password for jhutar:

=====================================================
= Selected Image:
= Fedora-IoT-39.20231103.1-20231103.1.aarch64.raw.xz
= Selected Media : /dev/sda
= U-Boot Target : rpi4
= Root Password will be removed.
= Root partition will be resized
= SSH Public Key /home/jhutar/.ssh/id_rsa.pub will be added.
=====================================================

*****************************************************
*****************************************************
******** WARNING! ALL DATA WILL BE DESTROYED ********
*****************************************************
*****************************************************
= Writing:
= Fedora-IoT-39.20231103.1-20231103.1.aarch64.raw.xz
= To: /dev/sda ....
4282384384 bytes (4.3 GB, 4.0 GiB) copied, 243 s, 17.6 MB/s
1024+0 records in
1024+0 records out
4294967296 bytes (4.3 GB, 4.0 GiB) copied, 243.92 s, 17.6 MB/s
= Writing image complete!
= Resizing /dev/sda ....
Checking that no-one is using this disk right now ... OK

Disk /dev/sda: 29.72 GiB, 31914983424 bytes, 62333952 sectors
Disk model: UHSII uSD Reader
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xc1748067

Old situation:

Device Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 1028095 1026048 501M 6 FAT16
/dev/sda2 1028096 3125247 2097152 1G 83 Linux
/dev/sda3 3125248 8388607 5263360 2.5G 83 Linux

/dev/sda3:
New situation:
Disklabel type: dos
Disk identifier: 0xc1748067

Device Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 1028095 1026048 501M 6 FAT16
/dev/sda2 1028096 3125247 2097152 1G 83 Linux
/dev/sda3 3125248 62333951 59208704 28.2G 83 Linux

The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.
e2fsck 1.46.5 (30-Dec-2021)
/dev/sda3 has unsupported feature(s): FEATURE_C12
e2fsck: Get a newer version of e2fsck!

root: ********** WARNING: Filesystem still has errors **********

resize2fs 1.46.5 (30-Dec-2021)
Please run 'e2fsck -f /dev/sda3' first.

= Raspberry Pi 4 Uboot is already in place, no changes needed.
= Removing the root password.
= Adding SSH key to authorized keys.

= Installation Complete! Insert into the rpi4 and boot.

There are some errors there, right? Well, I ignored them. RPi booted nicely, I was able to setup everything (more on that in some later blog) but then I have ran out of storage. Only then I noticed root filesystem was not extended (exactly as the error message says).

After some online search I figured I need e2fsprogs-1.47.0 or newer and (at the time?) it was only available in Fedora 39. So I upgraded and now I was able to write the image just fine:

$ sudo arm-image-installer --image Fedora-IoT-39.20231103.1-20231103.1.aarch64.raw.xz --media /dev/sda --addkey /home/jhutar/.ssh/id_rsa.pub --norootpass --resizefs --target=rpi4 -y
[sudo] password for jhutar:

=====================================================
= Selected Image:                                 
= Fedora-IoT-39.20231103.1-20231103.1.aarch64.raw.xz
= Selected Media : /dev/sda
= U-Boot Target : rpi4
= Root Password will be removed.
= Root partition will be resized
= SSH Public Key /home/jhutar/.ssh/id_rsa.pub will be added.
=====================================================
 
*****************************************************
*****************************************************
******** WARNING! ALL DATA WILL BE DESTROYED ********
*****************************************************
*****************************************************
= Writing:
= Fedora-IoT-39.20231103.1-20231103.1.aarch64.raw.xz
= To: /dev/sda ....
4282384384 bytes (4.3 GB, 4.0 GiB) copied, 245 s, 17.5 MB/s
1024+0 records in
1024+0 records out
4294967296 bytes (4.3 GB, 4.0 GiB) copied, 245.85 s, 17.5 MB/s
= Writing image complete!
= Resizing /dev/sda ....
Checking that no-one is using this disk right now ... OK

Disk /dev/sda: 29.72 GiB, 31914983424 bytes, 62333952 sectors
Disk model: UHSII uSD Reader
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xc1748067

Old situation:

Device     Boot   Start     End Sectors  Size Id Type
/dev/sda1  *       2048 1028095 1026048  501M  6 FAT16
/dev/sda2       1028096 3125247 2097152    1G 83 Linux
/dev/sda3       3125248 8388607 5263360  2.5G 83 Linux

/dev/sda3:
New situation:
Disklabel type: dos
Disk identifier: 0xc1748067

Device     Boot   Start      End  Sectors  Size Id Type
/dev/sda1  *       2048  1028095  1026048  501M  6 FAT16
/dev/sda2       1028096  3125247  2097152    1G 83 Linux
/dev/sda3       3125248 62333951 59208704 28.2G 83 Linux

The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.
e2fsck 1.47.0 (5-Feb-2023)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
root: 32041/164640 files (0.6% non-contiguous), 449099/657920 blocks
resize2fs 1.47.0 (5-Feb-2023)
Resizing the filesystem on /dev/sda3 to 7401088 (4k) blocks.
The filesystem on /dev/sda3 is now 7401088 (4k) blocks long.

= Raspberry Pi 4 Uboot is already in place, no changes needed.
= Removing the root password.
= Adding SSH key to authorized keys.

= Installation Complete! Insert into the rpi4 and boot.

Stick the card into RPi, connect power and ethernet cable and voila, I'm now able to SSH to RPi. I got the IP from my router management console from DHCP leases section.

Total newbie guide for MicroPython on ESP8266

OK, disclaimer first. I know completely nothing about microelectronics. With that in mind:

Mine goal is to create cheep battery powered thermometer which would be reporting temperature in fixed intervals using http via mine home router WiFi network. This was occupying mine mind from this article (in czech only, executive summary: ESP8266 is old, new and better ESP32 is on the way). Till reading that article I did not knew there is cheep SoC which can connect to WiFi and you can read from external sensors attached to it (i.e. thermometer). There is lots of guides for this exact thing.

Purchasing ESP8266 ESP-01 and USB programmer

On E-Bay I have bought 3 ESP8266 Serial WIFI Wireless Transceiver Module Send Receive LWIP AP+STA for $9.44 (I have no idea on what all these letters in the name mean, but you want ESP8266 version labelled as ESP-01). And because I'm scared of wiring anything myself, I have bought ESP01 Programmer Adapter UART GPIO0 ESP-01 Adaptateur ESP8266 USB nb (to connect ESP8266 to computer via serial port emulated via USB; you do not need to install any drivers on Fedora 24). It took less than 20 days to receive all the items.

Lets use Python

I like Python, so was very surprised that there is a way how to program in it on ESP8266: MicroPython - a lean and efficient Python implementation for microcontrollers and constrained systems - especially MicroPython port for the WiFi modules based on Espressif ESP8266 chip.

To be able to build MicroPython, we need to build esp-open-sdk first.

Building toolchain: esp-open-sdk

esp-open-sdk if SDK for software development with the Espressif ESP8266 chips and at the end, it had 3.8GB on the disk and it contains some non-open-source binary blobs and I do not understand majority of the README, so I have decided to work with that as different user on my Fedora 24 system:

# dnf install autoconf gcc gcc-c++ gperf bison flex texinfo patch libtool ncurses-devel expat-devel pyserial help2man
# useradd esp
# sudo -u esp -i
$ git clone https://github.com/pfalcon/esp-open-sdk.git
$ cd esp-open-sdk/
$ make

I have taken this partly from Starting IoT development in Fedora (ESP8266), from Building and Running MicroPython on the ESP8266 (they are building in virtual machine here) and from esp8266/README.md in MicroPython git linked above.

Building MicroPython ESP8266 port

Now here we build binary image we will later upload to the chip.

$ git clone https://github.com/micropython/micropython.git
$ cd micropython/
$ git submodule update --init
$ make -C mpy-cross
$ export PATH=/home/esp/esp-open-sdk/xtensa-lx106-elf/bin:$PATH
$ cd esp8266/
$ make axtls
$ make

Flashing (uploading) MicroPython image to ESP8266

First try to talk to original firmware

Plug ESP8266 board into the UART-to-USB converter firmly and put it into USB port. Now you will see bunch of messages in journal (tail it with # journalctl -f). We need device name (that differs based on which USB port you will use). Now you can connect to serial console:

<date> <hostname> kernel: usb 3-1: new full-speed USB device number 6 using xhci_hcd
<date> <hostname> kernel: usb 3-1: New USB device found, idVendor=1a86, idProduct=7523
<date> <hostname> kernel: usb 3-1: New USB device strings: Mfr=0, Product=2, SerialNumber=0
<date> <hostname> kernel: usb 3-1: Product: USB2.0-Serial
<date> <hostname> kernel: ch341 3-1:1.0: ch341-uart converter detected
<date> <hostname> kernel: usb 3-1: ch341-uart converter now attached to ttyUSB0
<date> <hostname> mtp-probe[10120]: checking bus 3, device 6: "/sys/devices/pci0000:00/0000:00:14.0/usb3/3-1"
<date> <hostname> mtp-probe[10120]: bus: 3, device: 6 was not an MTP device
<date> <hostname> systemd-udevd[10119]: Process '/usr/bin/setfacl -m g:lirc:rw ' failed with exit code 2.

$ screen /dev/ttyUSB0 115200

This will fail because your "esp" user does not have write permissions to /dev/ttyUSB0. What I did was I have added "esp" user to "dialout" group with # usermod -a -G dialout esp, logged out, in again and verified that I have the group with $ groups command. Once done, start screen again.

You can try some AT commands - e.g. to switch to "station" mode and then listing available "access points" (your home WiFi network should be amongst them) as noted in Getting Started with ESP8266 article. Note that you need to press "Ctrl+M" (i.e. carriage return, "Enter" worked for me as well) and "Ctrl+J" (i.e. linefeed) to submit each command.

AT+GMR
AT version:0.25.0.0(Jun  5 2015 16:27:16)
SDK version:1.1.1
Ai-Thinker Technology Co. Ltd.
Jun  5 2015 23:07:20

OK
AT+CWMODE=3

OK
AT+CWLAP
+CWLAP:(3,"Internet_80",-82,"5c:f4:ab:02:da:12",1)
+CWLAP:(3,"Stonehenge",-81,"48:5b:39:38:56:56",6)
+CWLAP:(3,"krakonos",-67,"10:c3:7b:d6:b8:34",10)

OK

Once done, to terminate screen, use "Ctrl+a \".

To get some detail on current serial port setup (mostly baud rate is important), use $ stty < /dev/ttyUSB0.

Upload new firmware

First you need to start into flashing mode - to do that you need to wire GPIO 0 to GND before pushing into USB port. If your USB-to-UART converter do not have any switch or so, you need to be creative. For me, one small wire squeezed between these two pins made the trick - see the photo :-)

No erase current flash content and upload yours (took me few tries to actually upload correct file, so make sure you are uploading build/firmware-combined.bin). It all takes below minute:

$ esptool.py -p /dev/ttyUSB0 -b 115200 erase_flash
$ esptool -p /dev/ttyUSB0 --baud 115200 write_flash --flash_size=8m --verify 0 build/firmware-combined.bin

So I have Python on that tiny chip now?

Remove whatever you have used to start in flashing mode and plug it in again to start in normal mode. Again, use screen to connect. Press "Enter" and say wow, familiar >>> is here!

>>> print("Hello world")
Hello world
>>> print(sys.version)
3.4.0
>>> print(sys.implementation)
(name='micropython', version=(1, 8, 4))
>>> print(sys.platform)
esp8266

Next step would be to learn how to access wifi in MicroPython.