raspberry pi

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Gpiozero Flow
2 months ago
- Gpiozero is a Python library for Raspberry Pi that simplifies GPIO programming by focusing on devices like buttons and LEDs instead of low-level electrical details.
- The library supports three programming paradigms: procedural (looping), event-based (callbacks), and declarative (linking device states via source/values).
- Gpiozero uses standard value ranges for devices (e.g., 0–1 for LEDs, -1–1 for motors), enabling direct value stream connections and manipulations.
- Functions like negated, smoothed, and sin_values allow easy manipulation and combination of value streams between devices.
- The gpiozero-flow project is a web-based UI that lets users drag-and-drop GPIO devices, connect them, and simulate or control them, inspired by gpiozero's source/values model.
- Features include a Python code generator, remote GPIO control via websockets (with HTTPS workaround using local packaging), and support for add-on boards, composite devices, and shareable canvas configurations.
- The tool is experimental, aimed at computational thinking or systems/control education, rather than advanced programming; potential extensions include event-based support and custom generators.
Review of the Uputronics GPS/RTC Raspberry Pi Expansion Board - Bert Hubert's writings
2 months ago
- The Uputronics GPS/RTC Raspberry Pi Expansion Board is a timing receiver featuring an u-blox M8 GNSS chip, priced at £41.99.
- It provides access to raw GNSS messages and correlator data, enabling sub-nanosecond precision for orbit determination and Doppler measurements.
- The board does not include an antenna but works with both high-end and cheap antennas, though better reception comes with a nicer one.
- Assembly on a Raspberry Pi 4 is straightforward with included hardware, but configuring the Pi requires disabling the login shell on the serial port while enabling the hardware serial port.
- The device communicates via UART1 at a default baudrate of 9600, but higher baudrates are recommended to handle data from multiple satellite constellations.
- It supports simultaneous tracking of GPS and Galileo (same frequency), plus one of BeiDou or GLONASS, but not all four at once.
- The expansion board is used as station 1 in the galmon.eu project and can also serve as a precise PPS time source with additional setup.
Downtown Doug Brown
2 months ago
- Need to change a 4K HDMI dummy plug's EDID to a 1080p one for compatibility.
- Use a Raspberry Pi's I2C controller to read and write the dummy plug's EEPROM.
- Enable I2C in raspi-config, install i2c-tools, and identify the correct I2C bus.
- Dump the original EDID using get-edid, then back it up before modifications.
- Dump the EDID from the target device (e.g., capture card) and write it to the dummy plug using i2cset.
- Verify the write by dumping and comparing with diff; success if no output.
- Warning: Only attempt on dummy plugs or devices you are willing to brick; avoid real monitors or PCs.
- Potential issues include write-protect pins, speed (add sleep between writes), and larger EDIDs beyond 256 bytes.
<antirez>
2 months ago
- Raspberry Pi is a popular platform for embedded and IoT programming, and Redis is well-suited for data storage on it due to its small memory footprint and append-only write pattern.
- Adapting Redis to ARM processors required handling unaligned memory accesses: ARM v6 handles word-sized accesses but not multi-word or floating-point instructions, and the Linux kernel's fix-up is slow and incomplete.
- Redis now defines USE_ALIGNED_ACCESS for architectures lacking unaligned support, using memcpy for safe access and fixing crashes on ARM and SPARC.
- The hash function was updated to SipHash for security and alignment safety, replacing Murmurhash2.
- Performance on Pi 3 reaches ~28,000 ops/sec (non-pipelined) and ~80,000 ops/sec with pipelining; on older Model B, it's ~2,000 ops/sec.
- Future plans include integrating stream data type in Redis 4.2 for IoT data bus and making Pi a primary target platform for Redis.
- The author invites community feedback on embedded applications and improvements.
Build your own Dial-up ISP with a Raspberry Pi
2 months ago
- Recreated a local dial-up ISP using a Raspberry Pi, phone line simulator, and USB modem to emulate late-90s internet access.
- Connected an iBook G3 via the phone line simulator, achieving speeds up to 33.6 kbps over POTS.
- Configured Linux tools mgetty and PPP on the Pi to handle modem calls and network bridging.
- Used Macproxy Classic to translate modern websites into barebones HTML for old browsers like Internet Explorer 5.
- Integrated the setup with an AirPort base station to provide dial-up speeds over 802.11b Wi-Fi.
- Refurbished the iBook's battery to experience untethered wireless dial-up, similar to 1999 usage.
- Explored the Wayback Machine extension in Macproxy to browse historical versions of websites.
- Learned about modem handshakes, PPP, QAM, and how vintage tech informs modern networking.
Raspberry Pi Connect may control Windows soon
2 months ago
- Raspberry Pi Connect, currently a free remote access service for Raspberry Pi devices, is reportedly gaining support for remote control of Windows PCs.
- The service uses WebRTC and VNC standards; a beta Windows version is available but has known bugs like cursor misalignment, freezes, and resolution issues.
- The tool is free for individuals, with a business plan at $0.50 per device per month, potentially undercutting competitors like RealVNC.
- Remote shell access (Command Prompt, PowerShell, WSL) is functional, though only one shell type can be set as the default.
- macOS daemon support may also be in development, as the Pi Connect team uses Macs internally.
- Key missing features include audio support, but the service continues to evolve with fleet management capabilities like remote updates.
SBC Clusters are a terrible value, but they're fun anyway
2 months ago
- SBC clusters offer poor value for money but are enjoyable for hobbyists and learning HPC.
- The DeskPi Super4C improves on the Super6C with ESP32 remote management and dual Ethernet/power inputs.
- A minimum cluster with four Raspberry Pi CM5s costs about $600, and a full build can reach $1,400, far more than a comparable mini PC.
- In HPL benchmarks, the Super4C performed similarly to student-built clusters in the SBCC competition.
- Use cases include HPC tinkering, multi-camera vision processing, Arm build farms, and redundant edge computing.
- For a simple homelab, a single mini PC is more cost-effective than an SBC cluster.
The Special Value Pi 4 was extremely short-lived
2 months ago
- The Special Value Pi 4 is a rare, binned version certified to run at 1.25 GHz instead of the standard 1.8 GHz.
- It was briefly listed by a reseller; the author bought two 4GB models for $160 total, including shipping and tariffs.
- Externally, the boards are identical to retail Pi 4s, but the 8GB model had an older B0 stepping and caused kernel panics at 1.8 GHz.
- One unit actually ran at 1.8 GHz, while the other required forcing to 1.25 GHz to boot stably.
- Power consumption at idle was unusually high (3W) compared to typical Pi 4s (<2W), due to voltage adjustments for lower-binned chips.
- A Raspberry Pi engineer explained that less than 0.01% of Pis fail validation and are sold to industrial customers at a discount, with DVFS normalizing performance across all chips.
- The article illustrates the silicon lottery and provides insight into parts binning behind the scenes.
10" Raspberry Pi Touch Display 2 is $80
2 months ago
- Raspberry Pi launched a new 10-inch Touch Display 2 priced at $80.
- It features a 1200x1920 resolution, 85-degree viewing angle, and 10-finger touch support.
- The display is compatible only with Raspberry Pi 5 and Compute Module boards, not with Pi 4 or earlier models.
- It is powered directly from the host Raspberry Pi and includes all necessary cables and mounting hardware.
- Raspberry Pi OS provides full driver support for the capacitive touchscreen without manual calibration.
- The display is suited for applications like home automation dashboards, kiosks, robotics interfaces, and digital signage.
- Previous 5-inch and 7-inch variants are available for older Raspberry Pi models.
It's time to wake up: An Emacs alarm clock
2 months ago
- The author has used a custom alarm clock system since 2011, relying on a numpad for input and a screen to display time, with a music server to play audio at the set time.
- The old system had reliability issues: network dependency, music server failures, and ambient music playback problems, leading to the use of an iPhone as a backup.
- The author decided to build a new self-contained alarm clock, keeping the numpad but eliminating network and external component dependencies.
- Components include a Raspberry Pi 5, a 4-inch screen, a Yoctopuce light sensor, a numpad, knobs, and a USB speaker, all housed in a custom wooden box.
- The author detailed the woodworking process: cutting laminated wood, using jigsaw blades, sanding, spackling, painting, and assembling the box with hinges and screws.
- Challenges included mis-measurements, cable compatibility issues, paint mishaps, and finding appropriate hardware for thin wood.
- The final clock works: the numpad is clicky, the interface is intuitive, and the light sensor dims the screen, though backlight control remains a limitation.
- The author declared the project a success, noting lessons learned about painting, workspace, and woodworking tools.
Raspberry Pi 5 Iommu Driver Being Worked on for the Mainline Linux Kernel
3 months ago
- Raspberry Pi 5's IOMMU driver is being adapted for the mainline Linux kernel, improving support over two years after release.
- Open-source developer Daniel Drake is leading the effort, adapting the downstream driver with enhancements like generic page table management.
- The driver integrates with the display controller for efficient graphics memory management, using 4KB pages, though 12KB is wasted with the default 16KB kernel PAGE_SIZE.
- Code review is underway, with the goal of upstream inclusion to benefit Raspberry Pi 5 users running the mainline kernel.

raspberry pi

Gpiozero Flow

Review of the Uputronics GPS/RTC Raspberry Pi Expansion Board - Bert Hubert's writings

Downtown Doug Brown

<antirez>

Build your own Dial-up ISP with a Raspberry Pi

Raspberry Pi Connect may control Windows soon

SBC Clusters are a terrible value, but they're fun anyway

The Special Value Pi 4 was extremely short-lived

10" Raspberry Pi Touch Display 2 is $80

It's time to wake up: An Emacs alarm clock

Raspberry Pi 5 Iommu Driver Being Worked on for the Mainline Linux Kernel