GPIO Announcer

4 hours ago

GPIO announcer is a quick hack for testing microcontroller pin assignments after PCB assembly.
It uses a CircuitPython script (or C .uf2) that drives all GPIOs simultaneously, each pin sending its name at 115200 baud via serial.
Serial converter like TermDriver can be connected to any pin to read the continuously transmitted name, confirming the connection.
The script detects floating pins and only transmits on those not already connected to an input.
Inspired by an FPGA implementation by Alex Forencich, the RP2040 version uses a PIO program to send data on all GPIOs at once.

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.

The author built a physical 17x17 matrix of switches with integrated LEDs to simulate Conway's Game of Life, using a microcontroller (AVR128DA64) to control rows and columns.
The LED display uses a multiplexing scheme where each row is active for 1/17th of the time, requiring higher current (150 mA per LED) to maintain brightness, with MOSFETs for row and column switching.
User input is detected by reusing row select lines to ground and sensing switch closures via GPIO pins, with pull-up resistors integrated on the MCU.

<antirez>8 days ago

The Raspberry Pico is a well-made, durable chip with a ton of features, including state machines for GPIOs, and its lack of connectivity is resolved by the W variant.
The chip is well supported by MicroPython and the C SDK, though the build system is overcomplicated for small programs.
To generate sound without a DAC, PWM can be used with a high frequency and varying duty cycles to approximate different voltage levels.

The article describes implementing a digital circuit simulator in Haskell, closely following SICP's approach using mutable state and message-passing.
Wires are defined with IORefs for signal value and action procedures, enabling the observer pattern where downstream components subscribe to signal changes.
Basic gates (inverter, and_gate, or_gate) are implemented as action procedures that update output wires after a delay, using a global mutable agenda for scheduling.

A 16-bit serial homebrew CPU was built using only 8 ICs, including memory and clock, achieving Turing completeness.
The CPU uses a single EPROM as both control state machine and 1-bit ALU, with two serial SRAMs and one serial FLASH.
It executes around 12,000 instructions per second at up to 10 MHz, capable of streaming video on a Nokia 5110 LCD at ~10 FPS.

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.

The author built a physical 17x17 matrix of switches with integrated LEDs to simulate Conway's Game of Life, using a microcontroller (AVR128DA64) to control rows and columns.
The LED display uses a multiplexing scheme where each row is active for 1/17th of the time, requiring higher current (150 mA per LED) to maintain brightness, with MOSFETs for row and column switching.
User input is detected by reusing row select lines to ground and sensing switch closures via GPIO pins, with pull-up resistors integrated on the MCU.

<antirez>8 days ago

The Raspberry Pico is a well-made, durable chip with a ton of features, including state machines for GPIOs, and its lack of connectivity is resolved by the W variant.
The chip is well supported by MicroPython and the C SDK, though the build system is overcomplicated for small programs.
To generate sound without a DAC, PWM can be used with a high frequency and varying duty cycles to approximate different voltage levels.

The article describes implementing a digital circuit simulator in Haskell, closely following SICP's approach using mutable state and message-passing.
Wires are defined with IORefs for signal value and action procedures, enabling the observer pattern where downstream components subscribe to signal changes.
Basic gates (inverter, and_gate, or_gate) are implemented as action procedures that update output wires after a delay, using a global mutable agenda for scheduling.

A 16-bit serial homebrew CPU was built using only 8 ICs, including memory and clock, achieving Turing completeness.
The CPU uses a single EPROM as both control state machine and 1-bit ALU, with two serial SRAMs and one serial FLASH.
It executes around 12,000 instructions per second at up to 10 MHz, capable of streaming video on a Nokia 5110 LCD at ~10 FPS.

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