Francis Stokes

@francis.codes

303 Followers 489 Following

Exploring the Low Level on YouTube as Low Byte Productions Firmware Engineer Father x2 (he/him) 🇬🇧🇳🇱

Overhear view of the keyboard with the white 3d printed tenting risers set apart.
A 40% split mechanical keyboard. Both halves are black, symmetrical, with all black keys, except the F, J, and the two space bar keys which are white. None of the keys have symbols. The left half has an exposed raspberry Pi pico, where a USB C cable plugs in. The right half has a decorative feature where the pico would be. The two halves are connected with a decorative cable sheaved in patterned black and white paracord. Both sides are raised up on a small white platform to create an approximate 15° tenting angle.
A view of the fully assembled keyboard on a wooden table. A coiled USB C cable plugs into an exposed raspberry pi pico board which is mounted to the top plate of the keyboard. On either side of the pico sits 24 keys - a distance of about 3cm apart. The keycap set is grayscale, with the bottom row of keys all being white, and the next 3 becoming progressively darker in value. Under the pico there are 4 WS2812 LEDs used for status.
Hexagonal fractal constructed by drawing a circle, with 6 circles inside, and each circle gets 6 more circles inside, etc
A serpinsky triangle, constructed by recursively drawing a circle, with 3 circles inside with half the radius, with each circle getting 3 more, and so on.
A custom built pen plotter, sitting on a (somewhat) messy wooden desk. There is a sharpie pen in the modular pen holder. It appears to be drawing an interrupted circle. To the left of the machine is an organised chaos of wiring harnesses, going off to a couple of hand soldered boards, with an STM32 nucleo devboard at the heart. To the right, tweezers, a crimp tool, and a partial laptop can be seen.
Two sides of a ziggo remote control. One side is a normal TV remote, and the other I a little keyboard, intended for use with a media center package
Overhead shot of my mechanical keyboard on my desk. The micro USB end goes into a little black box, with a two position switch. Two USB-A wires come out of two sides of the black box, going off to different computers.
#define ENTROPY_POOL_SIZE (32) __attribute__((section(".noinit"))) static u32 ram_entropy_pool[ENTROPY_POOL_SIZE]; static void init_xorshift(void) { u32 seed = 0; for (u32 i = 0; i < ENTROPY_POOL_SIZE; i++) { seed += ram_entropy_pool[i]; } xorshift32_seed(seed); for (u32 i = 0; i < ENTROPY_POOL_SIZE; i++) { ram_entropy_pool[i] = xorshift32_get(); } }
A screenshot of my podcast feed, opened on the podcast "Roguelike Radio". It shows a new episode uploaded 18 hours again, with the last one before that being 4 years ago.
typedef struct TCPConnection_t { ... QueueHandle_t rx_queue; QueueHandle_t tx_queue; SemaphoreHandle_t rx_lock; SemaphoreHandle_t tx_lock; SemaphoreHandle_t state_lock; SemaphoreHandle_t unacked_lock; SemaphoreHandle_t unprocessed_lock; SemaphoreHandle_t rx_queue_lock; SemaphoreHandle_t tx_queue_lock; SemaphoreHandle_t rx_queue_empty; SemaphoreHandle_t tx_queue_empty; SemaphoreHandle_t rx_queue_full; SemaphoreHandle_t tx_queue_full; SemaphoreHandle_t rx_queue_not_full; SemaphoreHandle_t tx_queue_not_full; SemaphoreHandle_t rx_queue_not_empty; SemaphoreHandle_t tx_queue_not_empty; SemaphoreHandle_t rx_queue_not_empty_and_not_full; SemaphoreHandle_t tx_queue_not_empty_and_not_full; SemaphoreHandle_t rx_queue_empty_and_not_full; SemaphoreHandle_t tx_queue_empty_and_not_full; SemaphoreHandle_t rx_queue_empty_and_not_empty; SemaphoreHandle_t tx_queue_empty_and_not_empty; SemaphoreHandle_t rx_queue_full_and_not_empty; SemaphoreHandle_t tx_queue_full_and_not_empty; SemaphoreHandle_t rx_queue_full_and_not_full; SemaphoreHandle_t tx_queue_full_and_not_full; SemaphoreHandle_t rx_queue_empty_and_not_full_and_not_empty; SemaphoreHandle_t tx_queue_empty_and_not_full_and_not_empty; SemaphoreHandle_t rx_queue_full_and_not_full_and_not_empty; SemaphoreHandle_t tx_queue_full_and_not_full_and_not_empty; SemaphoreHandle_t rx_queue_empty_and_not_full_and_not_empty_and_not_full; SemaphoreHandle_t tx_queue_empty_and_not_full_and_not_empty_and_not_full; SemaphoreHandle_t rx_queue_full_and_not_full_and_not_empty_and_not_full; SemaphoreHandle_t tx_queue_full_and_not_full_and_not_empty_and_not_full; SemaphoreHandle_t rx_queue_empty_and_not_full_and_not_empty_and_not_full_and_not_empty; SemaphoreHandle_t tx_queue_empty_and_not_full_and_not_empty_and_not_full_and_not_empty; SemaphoreHandle } TCPConnection_t;
A block diagram showing the firmware and packet flow architecture. On the edge of the system there is a SPI/Ethernet connection. That is connected to a "net" block, which h contains a "w5100 driver" abstracted by a "generic ethernet driver". Received packets flow into a layer containing an IP module (and an unimplemented ARP module), from IP into UDP (as well as unimplemented TCP and ICMP modules), and from UDP to a queue on the DHCP module. Outgoing packets flow back up through the same layers.
Close up (almost macro) shot of a a bodged arduino ethernet shield, plugged into an STM32 nucleo development board, plugged into a not-completely-discernible protoboard. There are wires of various kinds sprawling out of different parts of the stacked device, and 4 prominent, shining LEDs marked: PWR, LINK, 100M, and FULLD
Laptop connected to a development board over USB, with a logic analyser attached to the board and connected to the laptop over USB, and an ethernet connection between the laptop and the board.