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Open Hardware/Modding: Reverse-engineering, ESP32, and More
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Ken Shirriff ☛ Reverse-engineering the vintage Intel 8087's tangent algorithm: more than CORDIC
By examining the circuitry and microcode of the 8087, I can explain the algorithm behind the tangent instruction, called FPTAN. To explore the 8087's circuitry, I popped the lid off a chip with a chisel and created a high-resolution image with a microscope. The microcode ROM is the large rectangular region in the center of the die, holding the 1648 micro-instructions that control the chip. The bottom half of the chip (red box) is the datapath, the circuitry that performs floating-point calculations on 80-bit values.3
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Hackaday ☛ You Can Make A Microprocessor That’s All Your Own
The microprocessor itself is a little unusual, being a transport triggered architecture design with two busses. The whole thing might better be described as a system-on-chip than a microprocessor, as like a microcontroller it contains both memory and peripherals. He’s used Spade to design the thing, and we get an in-depth look at all the steps involved between design and fabrication. It’s a level or two more difficult than passing the DRC standards for your PCB fabricator. The result is a chip carrier with the chip itself visible under clear epoxy. It’s using an old fabrication technology so the silicon is surprisingly big, but unlike Tiny Tapeout’s cell based fabrication the whole chip is the one circuit. Mounting it on a PCB and using a breadboard, he’s able to demonstrate it running simple programs.
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Linux Gizmos ☛ ESP-Mosaico centers dual-core RISC-V ESP32-S31 around a 2.16-inch square AMOLED
The Espressif ESP-Mosaico is an expandable smart-interaction development kit based on the ESP32-S31 microcontroller. The compact device integrates a 2.16-inch square touch display, audio hardware, motion and magnetic sensors, NAND storage, haptic feedback and dual expansion interfaces for HMI, edge voice and multimedia applications.
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CNX Software ☛ LILYGO T-Dongle-C5 – An ESP32-C5 USB dongle with microSD card slot, optional 0.96-inch OLED
LILYGO T-Dongle-C5 is an ESP32-C5 dual-band WiFi 6, BLE, and 802.15.4 USB dongle that builds upon the earlier ESP32-S3-based T-Dongle-S3 board. The new board still features an optional 0.96-inch color display, a microSD card slot, and a USB-A male port. The main differences are support for dual-band WiFi 6, 16MB flash, 8MB PSRAM, and the addition of a Qwiic expansion connector.
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Linux Gizmos ☛ ESP32-S3 powers EWatch smartwatch with open drivers and DIY options
EWatch, developed by Ewan Wills, is a programmable ESP32-S3 smartwatch with a 1.69-inch color touchscreen, 350mAh battery, vibration feedback and USB-C connectivity. The platform is offered as a bare PCB, self-assembly kit or complete watch, following more than five years of development.