Raspberry pi: Difference between revisions
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* 1 x Gigabit Ethernet | * 1 x Gigabit Ethernet | ||
* RTC | * RTC | ||
** requires [https://core-electronics.com.au/raspberry-pi-5-rtc-battery.html?gad_source=1&gad_campaignid=17417005429&gbraid=0AAAAADlEpP4nk49vKTNI6JpJcLFEVyq57&gclid=EAIaIQobChMIt_qM1-alkQMV12wPAh22nzRUEAQYASABEgJWQ_D_BwE rechargable Maganese Lithium] battery | |||
* WiFi 802.11 dual band | * WiFi 802.11 dual band | ||
* BlueTooth 5 (BLE) | * BlueTooth 5 (BLE) | ||
Latest revision as of 17:19, 5 December 2025
gpio
pi models
- raspberry foundation models of interest for the category:student and category:lesson.
pi zero W
- how to set it up to discover wireless https://www.youtube.com/watch?v=3VO4vGlQ1pg
Tech Specs:
- BCM 2835 SoC (ARM11 at 1GHz)
- 512MB of RAM
- On-board Wi-Fi - 2.4 GHz 802.11 b/g/n (BCM43438)
- On-board Bluetooth 4.1 + HS Low-energy (BLE) (BCM43438)
- Storage: micro-SD
- Display: mini-HDMI
- Power: USB micro-B
- USB: 1 x USB micro-B
- CSI camera connector (requires adaptor cable)
- 40-pin GPIO connector )
- Compatible with existing pHAT/HAT add-ons
- Dimensions: 65mm x 30.5mm x 5mm
- Weight: 9.3g
pi 3B+

The Raspberry Pi 3 Model B+ is the final revision in the Raspberry Pi 3 range.
- Broadcom BCM2837B0, Cortex-A53 (ARMv8) 64-bit SoC @ 1.4GHz
- 1GB LPDDR2 SDRAM
- 2.4GHz and 5GHz IEEE 802.11.b/g/n/ac wireless LAN, Bluetooth 4.2, BLE
- Gigabit Ethernet over USB 2.0 (maximum throughput 300 Mbps)
- Extended 40-pin GPIO header
- Full-size HDMI
- 4 USB 2.0 ports
- CSI camera port for connecting a Raspberry Pi camera
- DSI display port for connecting a Raspberry Pi touchscreen display
- 4-pole stereo output and composite video port
- Micro SD port for loading your operating system and storing data
- 5V/2.5A DC power input
- Power-over-Ethernet (PoE) support (requires separate PoE HAT)
Compute Module 3+
The CM3+ Compute Module contains the guts of a Raspberry Pi 3 Model B+ (the BCM2837 processor and 1GB RAM) as well as an optional eMMC Flash device of 8GB, 16GB or 32GB (which is the equivalent of the SD card in the Pi).
- Broadcom BCM2837B0, Cortex-A53 (ARMv8) 64-bit SoC @ 1.2GHz
- 1GB LPDDR2 SDRAM
- 8GB/16GB/32GB eMMC Flash memory, or a Lite variant without eMMC Flash memory
This is all integrated onto a small (67.6mm × 31mm) board that fits into a standard DDR2 SODIMM connector. The Flash memory is connected directly to the processor on the board, but the remaining processor interfaces are available to the user via the connector pins. You get the full flexibility of the BCM2837 SoC (which means that many more GPIOs and interfaces are available than with a standard Raspberry Pi), and designing the Module into a custom system should be relatively straightforward because we’ve put all the tricky bits onto the Module itself.[1]
- 7-slot CM3 cluster board https://www.electronics-lab.com/turing-pi-launches-its-7-slot-raspberry-pi-cm3-cluster-board/
Features and Specifications of the Turing Pi include;
- Can load OS through SD card, eMMC or netboot.
- Has power management for each node.
- Supports Raspberry Pi Compute Modules 1, 3 and 3+.
- Has up to 7GB of RAM.
- Maximum of 224GB Internal eMMC.
- Maximum of 28 CPU cores.7x Micro SD slots (1 per node)
- Flash port for Master Node only via micro USB7x 40-pin GPIO,
- RPI compatible pinout7x DDR2 SO-DIMMI2C
- Cluster management
- bus1x External I2C ports for additional devices like EEPROM or LCD displays
- 128 Bytes of User space EEPROM
- 1x HDMI (Master Node)
- 8x USB 2.01x
- 1Gbps Ethernet port with switch to the 7 x 100Mbps NIC for each CM (are assigned own IP address)
- 1x Real-time clock
- 1x 3.5 mm Audio Jack
- Up to 40 W power consumption,
- 12V Mini ITX Power socket.
- Dimensions: 170 x 170 mm (6.7 x 6.7 inches)
pi 4
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- Broadcom BCM2711, Quad core Cortex-A72 (ARM v8) 64-bit SoC @ 1.5GHz
- 2GB, 4GB or 8GB LPDDR4-3200 SDRAM (depending on model)
- 2.4 GHz and 5.0 GHz IEEE 802.11ac wireless, Bluetooth 5.0, BLE
- Gigabit Ethernet
- 2 USB 3.0 ports; 2 USB 2.0 ports.
- Raspberry Pi standard 40 pin GPIO header (fully backwards compatible with previous boards)
- 2 × micro-HDMI ports (up to 4kp60 supported)
- 2-lane MIPI DSI display port
- 2-lane MIPI CSI camera port
- 4-pole stereo audio and composite video port
- H.265 (4kp60 decode), H264 (1080p60 decode, 1080p30 encode)
- OpenGL ES 3.1, Vulkan 1.0
- Micro-SD card slot for loading operating system and data storage
- 5V DC via USB-C connector (minimum 3A*)
- 5V DC via GPIO header (minimum 3A*)
- Power over Ethernet (PoE) enabled (requires separate PoE HAT)
- Operating temperature: 0 – 50 degrees C ambient
The raspberry pi 4 contains a flash boot loader which can be configured to use PXE boot
pi400
- Broadcom BCM2711 quad-core Cortex-A72 (ARM v8) 64-bit SoC @ 1.8GHz
- 4GB LPDDR4-3200
- Dual-band (2.4GHz and 5.0GHz) IEEE 802.11b/g/n/ac wireless LAN
- Bluetooth 5.0, BLE
- Gigabit Ethernet
- 2 × USB 3.0
- 1 × USB 2.0 ports
- Horizontal 40-pin GPIO header
- 2 × micro HDMI ports (supports up to 4Kp60)
- H.265 (4Kp60 decode); H.264 (1080p60 decode, 1080p30 encode); OpenGL ES 3.1, Vulkan 1.0
- MicroSD card slot for operating system and data storage
- 78- or 79-key compact keyboard (depending on regional variant)
- 5V DC via USB-C connector
- Operating temperature: 0°C to +50°C ambient
- Maximum dimensions 286 mm × 122 mm × 23 mm
Compute Module 4

The power of Raspberry Pi 4 in a compact form factor for deeply embedded applications. Raspberry Pi Compute Module 4 incorporates a quad-core ARM Cortex-A72 processor, dual video output, and a wide selection of other interfaces. Available in 32 variants, with a range of RAM and eMMC Flash options, and with or without wireless connectivity. [2] Contains:
- Broadcom BCM2711 quad-core Cortex-A72 (ARM v8) 64-bit SoC @ 1.5GHz
- H.265 (HEVC) (up to 4Kp60 decode), H.264 (up to 1080p60 decode, 1080p30 encode)
- OpenGL ES 3.1, Vulkan 1.0
- Options for 1GB, 2GB, 4GB or 8GB LPDDR4-3200 SDRAM (depending on variant)
- Options for 0GB ("Lite"), 8GB, 16GB or 32GB eMMC Flash memory (depending on variant)
- Option for fully certified radio module:
- 2.4 GHz, 5.0 GHz IEEE 802.11 b/g/n/ac wireless;
- Bluetooth 5.0, BLE;
- On-board electronic switch to select either external or PCB trace antenna
See also Networking#modbus_hardware [3]
Compute Module 4 IO Board
The compute module 4 has 2 x 100 pin connectors that mate with the Compute Module 4 IO Board to make an integrated development system, or reference board design. See https://youtu.be/aOH43s9lm7I

Specifications:
- External power connector (+12V, +5V)
- 2 x full-size HDMI 2.0 connectors
- 2 x USB 2.0 connectors, with header for two additional connectors
- Gigabit Ethernet RJ45 with PoE support
- Micro USB socket for updating Compute Module 4
- MicroSD card socket for Compute Module 4 Lite (without eMMC) variants
- PCIe Gen 2 x1 socket
- Standard fan connector
- 2 x MIPI DSI display FPC connectors (22-pin 0.5 mm pitch cable)
- 2 x MIPI CSI-2 camera FPC connectors (22-pin 0.5 mm pitch cable)
- Standard Raspberry Pi HAT connectors
- Real-time clock with battery socket and ability to wake Compute Module 4
- Various jumpers to disable specific features, e.g. wireless connectivity, EEPROM writing
- suppliers:
Compute Module 4 dual 1GBe carrier board
- https://wiki.seeedstudio.com/Dual-Gigabit-Ethernet-Carrier-Board-for-Raspberry-Pi-CM4/ [4]
- https://www.seeedstudio.com/blog/2021/06/11/how-to-build-a-raspberry-pi-router-step-by-step-tutorial/
- heatsink required https://www.seeedstudio.com/Aluminum-Alloy-CNC-Heat-Sink-with-Fan-for-Raspberry-Pi-CM4-Module-p-4923.html
- see also
- https://www.seeedstudio.com/Dual-GbE-Carrier-Board-with-4GB-RAM-32GB-eMMC-RPi-CM4-Case-p-5029.html
- https://www.jeffgeerling.com/blog/2021/two-tiny-dual-gigabit-raspberry-pi-cm4-routers
- $204 https://core-electronics.com.au/dual-gigabit-ethernet-carrier-board-for-raspberry-pi-cm4-with-4gb-ram-32gb-emmc.html
- U$108 https://www.seeedstudio.com/Rapberry-Pi-CM4-Dual-GbE-Carrier-Board-p-4874.html?utm_source=cnx_software&utm_medium=link&utm_campaign=cnx_software
- router board core electronics https://core-electronics.com.au/mini-router-with-raspberry-pi-compute-module-4-dual-gigabit-ethernet-4gb-ram-32gb-emmc.html
Features:
- Compact size (75x64x21mm) with rich I/O peripherals
- Dual Gigabit Ethernet connectors for soft router applications
- Camera/ display connectivity using MIPI CSI, MIPI DSI and micro-HDMI interfaces
- Onboard dual USB 3.0 with an additional USB 3.0 9-pin header for more external ports
- Micro-SD Card slot to load system image for non-eMMC version of CM4
- More Expandability via FPC Connector (I2C, SPI)
- External fan support with fan power connector
- Power using USB Type-C

SATA
DFRobot's dual 1Gbe
- https://linuxgizmos.com/tiny-dual-gbe-raspberry-pi-cm4-carrier-sells-for-30/
- US$45 https://www.dfrobot.com/product-2242.html?tracking=snqbbMs0lddTvr3eSVRKmzR6PWWGRVs9bZLm6dbDWV7auVnyVbcFCdESMTPnwDyr
- https://wiki.dfrobot.com/Compute_Module_4_IoT_Router_Board_Mini_SKU_DFR0767
No WiFi, No USB.
MikroPC
modBerry 500-CM4
MQTT gateway
9500-CM4
clusBerry CM4 cluster
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- Standard 9500-CM4 cluster module with Compute Module 4 and chosen configuration:
- I/O Controller with range of DI, DO, AI, 1-Wire, RS-232/485 and CAN interfaces
- Communication Gateway with wired (1/2x Ethernet, Serial Ports) and wireless interfaces (LTE-cat.M1, 4G, 5G, LoRa, ZigBee, Z-Wave, Wireless M-Bus)
- AI Gateway with 1x Coral from Google via PCIe M.2, introduced in December 2020: https://iiot-shop.com/product/ai-gateway/ or up to 4x Coral from Google via USB3.0
- NAS File Server with 2x/4x SSD SATA III and RAID support, managed with Nextcloud or ownCloud software
- USB3.0 Hub for 5G communication, Modems, AI Cluster and peripherals
- Gigabit LAN/WAN Router with additional 2.5GbE network card as an independent switch/router shielded from the mainboard cluster network
- SuperCap / Power management module for backup power supply (supercapacitors / Li-Ion battery) and sleep mode management aided with ESP32-module
- Additional expansion cards, with resources suited for the installation (DIO, AIO, Serial Ports and dedicated sensor cards, detailed below)
pi 5
The raspberry pi SBC contains:
- 2.5 GHz quad core 64 bit ARM Cortex-A76 BCM2712 CPU
- VideoCore VII GPU
- 1/2/4/8/16 GB of LPDDR4X RAM
- 2 x 4kp60 HDMI with HDR
- PCIe 2.0
- 2 x USB 2.0
- 2 x USB 3.0 (simultaneous 5 Gbps)
- 1 x Gigabit Ethernet
- RTC
- requires rechargable Maganese Lithium battery
- WiFi 802.11 dual band
- BlueTooth 5 (BLE)
- 4-pin fan connector
- microSd Card
- 3-pin UART connector
- USB-C power connector
PCIe HAT+

There are various PCIe HATs available, the one I purchased was the Wave Share HAT+
- https://www.raspberrypi.com/documentation/accessories/m2-hat-plus.html
- https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#nvme-ssd-boot
- https://www.waveshare.com/wiki/PCIe_TO_M.2_HAT%2B
pi cluster
pi desktop
Overview
rp 2040 and pico
A microcontroller released by raspberry pi.
Raspberry Pi Pico is a low-cost, high-performance microcontroller board with flexible digital interfaces. Key features include:
- RP2040 microcontroller chip designed by Raspberry Pi in the United Kingdom
- Dual-core Arm Cortex M0+ processor, flexible clock running up to 133 MHz
- 264KB of SRAM, and 2MB of on-board Flash memory
- Castellated module allows soldering direct to carrier boards
- USB 1.1 with device and host support
- Low-power sleep and dormant modes
- Drag-and-drop programming using mass storage over USB
- 26 × multi-function GPIO pins
- 2 × SPI, 2 × I2C, 2 × UART, 3 × 12-bit ADC, 16 × controllable PWM channels
- Accurate clock and timer on-chip
- Temperature sensor
- Accelerated floating-point libraries on-chip
- 8 × Programmable I/O (PIO) state machines for custom peripheral support
pico
- In this wiki pico is short for a raspberry foundation pico microcontroller,
- pico is a prefix for a unit of measure 1x10-12 used in the metric system for electronics and science,
- in computing pico is a screen based editor
pico W
The raspberry pico W is based on the RP2040 plus WiFi under the tin-can and a built-in antenna on the PCB (in place of where the logo was for the pico).

bootloader
- raspberry pi models
- USB mode
- raspberry pi 4 models
network boot
- https://linuxhit.com/raspberry-pi-pxe-boot-netbooting-a-pi-4-without-an-sd-card/
- https://williamlam.com/2020/07/two-methods-to-network-boot-raspberry-pi-4.html
- tutorial https://www.raspberrypi.org/documentation/hardware/raspberrypi/bootmodes/net_tutorial.md
- config https://www.raspberrypi.org/documentation/hardware/raspberrypi/bcm2711_bootloader_config.md
- See also pihole#PXE
operating system images
- https://www.raspberrypi.org/software/operating-systems/
- piaware https://flightaware.com/adsb/piaware/install
You can perform headless builds of raspberry pi computers by downloading your desired image and creating a flash card via dd
dd of=/dev/mmcblk0 if=image.bin bs=10M status=progress
Then you mount the first partition:
mount /dev/mmscbkl0p1 /mnt/mmcblk0p1
Enabled ssh via:
touhc /mnt/mmcblk0p1
Enable WiFi via:
vi /mnt/mmcblk0p1/wpa_supplicant.conf
country=AU # Your 2-digit country code
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
network={
ssid="arising"
psk="XXXX"
key_mgmt=WPA-PSK
}
other stuff
- upgrading https://www.tomshardware.com/how-to/upgrade-raspberry-pi-os-to-bullseye-from-buster
- hardening see sudo#hardening
- LTE https://www.twilio.com/docs/iot/supersim/getting-started-super-sim-raspberry-pi-sixfab-cellular-iot-hat
- PXE
- https://hackaday.com/2018/10/08/hack-my-house-running-raspberry-pi-without-an-sd-card/
- https://www.reddit.com/r/raspberry_pi/comments/4upj7y/psa_usb_and_pxe_booting_without_an_sd_card_on_the/
- pi4 https://www.reddit.com/r/raspberry_pi/comments/l7bzq8/guide_pxe_booting_to_a_raspberry_pi_4/
- Mikrotik https://blog.xentoo.info/2013/12/22/mikrotik-dhcp-and-pxe-boot/
- PoE https://www.youtube.com/watch?v=zH9GwYZu_aE
- dual ether https://www.sg-electronic-systems.com/ethercat-shield-for-raspberry-pi-etherc-v1-6/
- ripoffs
- Sugar Battery https://www.tindie.com/products/pisugar/pisugar2-battery-for-raspberry-pi-zero/?utm_source=hackaday&utm_medium=link&utm_campaign=fromstore
- RS-485 HAT
how to upgrade Debian OS
You may upgrade your raspberry pi relatively easily.
Note: You may employ the same apt techniques to upgrade Debian for any platform.
back the media up
- shutdown the pi
- remove the media card
- insert the card in a carrier and insert into a Linux system and back it up
dd if=/dev/mmcblk0 bs=1M status=progress | lz4 /sopmepath/my-raspbian-image.lz4
upgrade OS
On a running raspberry pi assume root or prefix command with sudo.
- create backups of your sources.list
cp /etc/apt/sources.list /etc/apt/source.list-backup
- upgrade the /etc/apt/sources.list and /etc/apt/sources.d/* lists from stretch to buster
sed -i 's/stretch/buster/g' /etc/apt/sources.list sed -i 's/stretch/buster/g' /etc/apt/sources.d/*.list
- now update apt
apt update
- inspect what will be upgraded
apt list --upgradable
- now do an upgrade
apt upgrade
- now do a dist-upgrade (Note: at later releases of Debian you can execute apt full-upgrade)
apt dist-upgrade
update the firmware
- update the firmware
rpi-update
undervoltage warning
When you have undervoltage detected [5]
- red LED will flash
- desktop will render lightning bolt on old versions or a message dialog on newer OS versions.
There are various commands that can be executed to see low voltage warning state:[6]
- dmseg
- vcgencmd
=displays
software
- GPIO dashboard https://www.instructables.com/Raspberry-Pi-GPIO-Web-Dashboard/?fbclid=IwAR0DA7XEqfyotn-oHPUHbpRKLfIk8Yw0tkm-0fK7S7lGD1MMaSQCSIfyvKs
- rotary encoders
hardware
TODO move this stuff to its own page.
- garage door opener https://core-electronics.com.au/projects/wifi-garage-door-controller-with-raspberry-pi-pico-w-smart-home-project/
- ADC/DAC
- $43.60 24-bit ADC 16-bit DAC https://www.amazon.com/dp/B083WN119J/?tag=showerclone-20
- $23.50 12-channel 12-bit ADC https://www.tindie.com/products/cburgess129/12-channel-12-bit-adc-hat-for-raspberry-pi/
- $41.99 10 channel 32-bit ADC https://www.waveshare.com/product/raspberry-pi/hats/ad-da-audio-sensors/18983.htm
- audio
- audio HAT comparisons https://tools.crazybikeriders.com/best-audio-hat-for-raspberry-pi/#B07KMRJKFL
- $18.99 https://www.waveshare.com/product/raspberry-pi/hats/ad-da-audio-sensors/wm8960-audio-hat.htm
- https://www.amazon.com.au/gp/product/B09JKD3KTZ/ref=pe_12099882_442640092_em_1p_0_ti
- http://www.crazy-audio.com/2013/11/quality-of-the-raspberry-pi-onboard-sound/
- https://au.element14.com/hifiberry/4260439550583/dac-adc-hi-res-dac-adc-for-rpi/dp/3404429?gclid=EAIaIQobChMInJqCjrOF9gIV6ZpmAh1PWwELEAQYASABEgL13vD_BwE&mckv=_dc%7Cpcrid%7C501152839127%7Cpkw%7C%7Cpmt%7C%7Cslid%7C%7Cproduct%7C3404429%7Cpgrid%7C123988903131%7Cptaid%7Cpla-293946777986%7C&CMP=KNC-GAU-GEN-SMART-SHOPPING
- $135 HiFiBerry https://www.hifiberry.com/docs/data-sheets/datasheet-dac-adc/
- $31.50 Raspberry Pi IQaudio DAC+ https://core-electronics.com.au/raspberry-pi-iqaudio-dac-48157.html?utm_source=google_shopping&gclid=EAIaIQobChMInJqCjrOF9gIV6ZpmAh1PWwELEAQYBCABEgLLa_D_BwE
- $6.58 MAX98337 3W audio amp
- $12.19 HiLetgo PCM5102 I2S IIS Lossless Digital Audio DAC Decoder Module Stereo DAC Digital-to-Analog Converter Voice Module for Arduino Raspberry Pi
- $6.58 3W class D audio https://www.amazon.com.au/gp/product/B07ZKJ8QN7/ref=pe_12099882_442595412_em_1p_0_ti
- $21 Waveshare WM8960 wiki https://www.waveshare.com/wiki/WM8960_Audio_HAT
- $14.93 3W Audio amp Adafruit Bonnet
- $29.26 RaspiAudio
- Lanzdo 25W HiFI Amp
- audio HAT comparisons https://tools.crazybikeriders.com/best-audio-hat-for-raspberry-pi/#B07KMRJKFL
- USB
- pico audio
- ALSA http://blog.scphillips.com/posts/2013/01/sound-configuration-on-raspberry-pi-with-alsa/
- Ham Radio HAT https://github.com/pa3gsb/Radioberry-2.x/wiki
- sensor HAT
- $34.99 waveshare environment sensor HAT https://www.waveshare.com/environment-sensor-hat.htm
- $29.99 waveshare sense HAT accelerometers, temp, humidity, barometric pressure, 4xADC, 4 Digital https://www.waveshare.com/product/raspberry-pi/hats/ad-da-audio-sensors/sense-hat-b.htm
micro sdcard
- https://www.amazon.com.au/SanDisk-Ultra-microSDHC-Memory-Adapter-dp-B08GY9NYRM/dp/B08GYBBBBH/ref=dp_ob_title_ce?th=1
- https://www.amazon.com.au/gp/product/B08J4HJ98L/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&th=1
- https://www.officeworks.com.au/shop/officeworks/c/technology/hard-drives-data-storage/sd-cards/micro-sdhc-sdxc-cards
- https://www.jbhifi.com.au/collections/computers-tablets/sd-cards
pico
- IMU https://raspberry.piaustralia.com.au/products/pico-10dof-imu-ic-test-board
- UPS https://raspberry.piaustralia.com.au/products/pico-uninterruptible-power-supply
- 240x135 LCD $14.55 https://raspberry.piaustralia.com.au/products/pico-lcd-1-14-ic-test-board
- 296x128 ePaper $28.55 https://raspberry.piaustralia.com.au/products/pico-epaper-2-9-ic-test-board
- breakout https://www.amazon.com.au/Treedix-Compatible-Raspberry-Breakout-Flexible/dp/B091F7YSCD/ref=pd_rhf_d_se_s_pd_crcd_sccl_2_4/357-6972105-8030507?pd_rd_w=ug1Rg&content-id=amzn1.sym.3773418f-973d-4eab-a18e-142337dd5ace&pf_rd_p=3773418f-973d-4eab-a18e-142337dd5ace&pf_rd_r=8G9MFHGATDAZP6H1H9Z6&pd_rd_wg=4sxTt&pd_rd_r=381474d7-6937-469e-9bce-d3f35fbd69b4&pd_rd_i=B091F7YSCD&psc=1
raspberry pi CVE
- https://cve.mitre.org/cgi-bin/cvekey.cgi?keyword=raspberry
- https://www.bleepingcomputer.com/news/security/linux-system-service-bug-gives-root-on-all-major-distros-exploit-released/
references
- ↑ raspberry pi cm3+ datasheet https://datasheets.raspberrypi.org/cm/cm3-plus-datasheet.pdf
- ↑ cm4 datasheet https://datasheets.raspberrypi.org/cm4/cm4-datasheet.pdf
- ↑ modbus hardware
- ↑ see https://wiki.seeedstudio.com/Dual-Gigabit-Ethernet-Carrier-Board-for-Raspberry-Pi-CM4/
- ↑ undervoltage https://pimylifeup.com/raspberry-pi-low-voltage-warning/
- ↑ undervoltage https://pimylifeup.com/raspberry-pi-low-voltage-warning/



















