ESP32-S3 WiFi bridge for a USB printer

 

MAXXTANG published a project on Hackster.io that puts a USB-only Brother HL-1110 laser printer on a WiFi network using an ESP32-S3. The computer prepares the job with the normal Brother driver and sends it to TCP port 9100. The ESP32-S3 passes the bytes  through its USB Host port to the printer.

The board’s native USB port goes to an OTG adapter and then the printer, while the separate UART port handles flashing and power. A charge-only adapter will not work. The firmware is an Arduino sketch built with the Espressif ESP32 board package, and it is set up for an N16R8 board with 16 MB flash and OPI PSRAM.

On first boot the board brings up a PrintServer-Setup access point at 192.168.4.1 for entering 2.4 GHz WiFi credentials. After that, a browser dashboard at http://hl1110.local shows printer status, WiFi settings and a restart control. The build also includes mDNS, a watchdog, OTA updates and a 512 KB PSRAM print buffer.

This is a raw port-9100 bridge with no AirPrint, IPP or LPD, and no authentication, so it is meant for a trusted local network. Code is MIT licensed.

See more at hackster.io and content on GitHub.

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How do touchscreens work?

Shri Khalpada walks through the two main kinds of touchscreen, with interactive demos, at PerThirtySix.

Resistive screens stack two conductive layers with spacer dots between them. The controller puts a voltage slope across one layer and reads the other. Press down and the layers meet at one point, and the voltage read there says how far across the press was. Two readings, one for X and one for Y, happen a hundred or more times a second. Pressure is all it takes, so a gloved hand or a stylus works. Two fingers do not: the readings blend into one point in the middle.

Capacitive screens instead use a grid of sender and listener electrodes under the glass. Your finger, being salty water, pulls part of the field away and the listener gets less signal.

Khalpada notes a phone has only a few hundred crossings, not thousands, and that controllers find the strongest crossing then average its neighbors for sub-grid precision. Palms are ignored because their cluster is too big. Water causes trouble when your finger touches it, smearing the touch across the screen.

See more at perthirtysix.com.

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Inside the Intel 8087 chip: floating-point addition and subtraction

Ken Shirriff has published a look at how the Intel 8087 math coprocessor performs floating-point addition and subtraction. The 1980 chip sped up floating point in the IBM PC and other systems, with addition running roughly 100 times faster than emulation on the 8086.

Shirriff opened a chip with a chisel and photographed the die under a microscope. The microcode ROM sits in the center and holds 1648 micro-instructions. The bottom half of the die is the datapath, built around a 69-bit integer adder, a shifter that can move a 68-bit value any number of positions, leading zero detection circuitry, and an exponent converter.

The post walks through the microcode step by step: aligning the binary points, choosing between unsigned addition and unsigned subtraction based on the argument signs, normalizing the result, and adjusting the exponent. It also covers the special cases for infinity, Not-a-Number, denormals, pseudo-zeros, and positive and negative zero. Shirriff worked with members of the Opcode Collective, who extracted the microcode from the ROM images.

See more at righto.com and content on GitHub.

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Logic Tutor, a kit for learning about logic gates

MonkMakes has posted a product page for the Logic Tutor, a kit for learning about logic gates. The kit comes with the Logic Tutor board, connecting wires and a printed instruction manual.

It runs on a single AAA battery, which is not included. The SKU is 00120. The product page links a datasheet PDF, an instructions PDF and a ZIP of product images.

No retailers are carrying it yet, so the page asks readers to watch for stock. Questions go to support@monkmakes.com.

See more at monkmakes.com.

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An illustrated online book on Hewlett-Packard equipment

A free 550 page e-book collects classic Hewlett-Packard test gear from the 1950s to the 1990s, with photos, schematics notes and restoration tips. Most of the instruments covered are ones the writer owns and tested.

Sections cover voltmeters, including the 400H vacuum tube voltmeter and the 410C with its photoconductive chopper amplifier, the 8640B signal generator, the 8015A pulse generator, the 54502A and 54540A oscilloscopes, the 5316B counter, the 141T spectrum analyzer with the 8553B and 8552B plug-ins, and the 8443A tracking generator.

Calculators get their own section: the HP-35, 45, 67 and 41C, plus the HP-85 computer. There is also a chapter on HP-IB, the interface bus better known as IEEE-488.

See more at k100.biz. (a large PDF)

Via Dave Jones on X.

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The Python on Microcontrollers Newsletter: subscribe for free

The Python for Microcontrollers Newsletter is the place for the latest news involving Python on hardware (microcontrollers AND single board computers like Raspberry Pi).

This ad-free, spam-free weekly email is filled with CircuitPython, MicroPython, and Python information that you may have missed, all in one place!

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The Python on Microcontrollers Newsletter: subscribe for free

The Python for Microcontrollers Newsletter is the place for the latest news involving Python on hardware (microcontrollers AND single board computers like Raspberry Pi).

This ad-free, spam-free weekly email is filled with CircuitPython, MicroPython, and Python information that you may have missed, all in one place!

You get a summary of all the software, events, projects, and the latest hardware worldwide once a week, no ads! You can cancel anytime.

It arrives about 11 am Monday (US Eastern time) with all the week’s happenings.

And please tell your friends, colleagues, students, etc.

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