RSS Parrot

Blinking a LED using STM32 DMA

https://lab.whitequark.org/notes/2023-07-22/blinking-a-led-using-stm32-dma/

Published: July 22, 2023 03:37

Every embedded developer has blinked a LED—this is both a rite of passage and a smoke test for bring-up of new hardware. Most often you do it in software. Sometimes you do it by connecting the LED directly to a peripheral. Have you ever blinked a LED…

Minimizing logic expressions

https://lab.whitequark.org/notes/2020-04-06/minimizing-logic-expressions/

Published: April 6, 2020 17:25

While working on reverse-engineering the Microchip ATF15xx CPLD family, I found myself deriving minimal logic functions from a truth table. This useful because while it is easy to sample all possible states of a black box combinatorial function using e.g.…

Synthesizing optimal 8051 code

https://lab.whitequark.org/notes/2020-04-06/synthesizing-optimal-8051-code/

Published: April 6, 2020 16:44

While working on an application targeting Nordic nRF24LE1, a wireless SoC with a fairly slow 8051 core, I was wondering if I can have fast, or at least not unusably slow, cryptography. Most cryptographic algorithms involve wide rotates, and the 8051 only…

Undocumented nRF24LU1+ quirks

https://lab.whitequark.org/notes/2020-01-27/undocumented-nrf24lu1-quirks/

Published: January 27, 2020 23:48

While working with nRF24LU1+, I discovered that the chip has lots and lots of odd corners that are sparsely or strangely documented, where the silicon doesn’t match documentation, etc.

Pixel Pawn wireless flash trigger on-air protocol

https://lab.whitequark.org/notes/2020-01-25/pixel-pawn-wireless-flash-trigger-on-air-protocol/

Published: January 25, 2020 18:43

In this note I describe the on-air protocol of Pixel Pawn wireless flash trigger.

Patching nVidia GPU driver for hot-unplug on Linux

https://lab.whitequark.org/notes/2018-10-28/patching-nvidia-gpu-driver-for-hot-unplug-on-linux/

Published: October 28, 2018 08:27

Recently, I’ve using an extremely cursed setup where my XPS 13 9360 laptop is connected to a Sonnet EchoExpress 2 box rewired for Thunderbolt 3 that has an nVidia Quadro 600 GPU, and Linux is set up for render offload to the eGPU and then frame transfer…

Game Boy Advance cartridge "SMC805-2 VER:1.5"

https://lab.whitequark.org/notes/2018-09-17/game-boy-advance-cartridge-smc805-2/

Published: September 17, 2018 11:02

I have been asked to determine if a (pirate) Game Boy Advance cartridge with the PCB marked “SMC805-2 VER:1.5 2006.11.16” can be reflashed. The cartridge contains a battery, an ASIC in a chip-on-board package (epoxy blob), an unidentified Intel chip marked…

Z144SN005 LCD microphotography

https://lab.whitequark.org/notes/2018-08-02/z144sn005-lcd-microphotography/

Published: August 2, 2018 05:50

I’ve been provided a Z144SN005 LCD that has split in halves as a result of excess mechanical force. Z144SN005 is a ST7735S-based LCD organized as 128RGB×128; it has 384 sources and 128 gates. I took some microphotographs of it using an Amscope…

Nokia 3220 transflective LCD microphotography

https://lab.whitequark.org/notes/2018-08-02/nokia-3220-transflective-lcd-microphotography/

Published: August 2, 2018 01:56

I took some microphotographs of a Nokia 3220 (RH-37) transflective LCD using an Amscope ME300TZ-2L-3M metallurgical microscope. These microphotographs were taken on an intact LCD, i.e. transmitted light images were acquired by shining a flashlight through…

Sony Xperia Z2 LCD microphotography

https://lab.whitequark.org/notes/2018-08-02/sony-xperia-z2-lcd-microphotography/

Published: August 2, 2018 00:33

I took some microphotographs of a counterfeit Sony Xperia Z2 LCD display, bought on Taobao circa 2017, using an Amscope ME300TZ-2L-3M metallurgical microscope. (This display would not initialize with an unmodified firmware, and was factory-programmed to…