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Stephen Holdaway stecman

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This is a collection of code snippets for various features on the STM8S family microcontrollers (specifically the STM8S003F3). These are written against the STM8S/A SPL headers and compiled using SDCC.

Some of this controller's functions aren't particularly intuitive to program, so I'm dumping samples for future reference here. These are based on the STM8S documentation:

Run at 16MHz

stecman /
Last active Feb 23, 2020
OpenCM3 USB clock configuration

USB with libopenCM3 on the STM32F070F6

This specific part doesn't work out of the box with the OpenCM3 STM32 F0 USB example/testcase for two reasons:

  • The USB pins (PA11/PA12) are hidden behind a mux on pins PA9/PA10 and need to be switched in. This physically connects the USB peripheral to the pins.
  • The STM32F070 must use an external oscillator to drive the 48MHz USB clock. My design used a 12MHz HSE, which libopencm3 didn't have a built-in clock configuration function for.
stecman / config.txt
Last active Jan 17, 2020
Raspberry Pi 2 B+ 1440x2560 resolution config
View config.txt
# Enable 1440x2560 resolution (mobile phone screen that expects this orientation)
stecman /
Created Jun 30, 2019
Dumping all bytecode from a packaged Python application

This is a technique for extracting all imported modules from a packaged Python application as .pyc files, then decompiling them. The target program needs to be run from scratch, but no debugging symbols are necessary (assuming an unmodified build of Python is being used).

This was performed on 64-bit Linux with a Python 3.6 target.


In Python we can leverage the fact that any module import involving a .py* file will eventually arrive as ready-to-execute Python code object at this function:

PyObject* PyEval_EvalCode(PyObject *co, PyObject *globals, PyObject *locals);
stecman /
Last active Feb 20, 2020 article to markdown converter for migrating or backing up projects/posts
#!/usr/bin/env python3
# Convert hackaday posts to markdown with images stored nearby
# This needs the following modules to run:
# -
# -
# -
stecman / AutoCrop.lua
Last active Jun 11, 2020
Lightroom plugin to calculate image crops using OpenCV
View AutoCrop.lua
-- LR imports
local LrApplication = import("LrApplication")
local LrApplicationView = import("LrApplicationView")
local LrBinding = import("LrBinding")
local LrDevelopController = import("LrDevelopController")
local LrDialogs = import("LrDialogs")
local LrExportSession = import("LrExportSession")
local LrFileUtils = import("LrFileUtils")
local LrFunctionContext = import("LrFunctionContext")
local LrLogger = import("LrLogger")
stecman / _NMEA GPS datetime for
Last active Oct 16, 2019
NMEA GPRMC sentence parsing for low memory microcontrollers: read GPS date and time from UART
View _NMEA GPS datetime for

Date/time from GPS without storing NMEA string

This is a first pass at reading the date and time from a serial GPS device on a tiny microcontroller. The target device is an ATTiny13A with only 64 bytes of RAM, which isn't enough to store the full 79 characters of a NMEA sentence, so something like minmea wouldn't work (their API passes around full sentence strings).

When compiled with avr-gcc -Os, this is around 500 bytes of program space. The size can be reduced by 100 bytes if the handling of checksums is removed.

stecman / BaseModel.php
Created Oct 14, 2018
Phalcon PHP modifiable array assignment of relationships on new objects
View BaseModel.php
use Phalcon\Mvc\Model;
* Configuration and behaviours for all models
abstract class BaseModel extends Model
stecman / avr_eprom_dump_over_serial.c
Last active Jul 19, 2018
Dump EPROM over serial with AVR
View avr_eprom_dump_over_serial.c
* Thrown together program to dump 512 kbit EPROMs from an AVR ATMega64A/128A
* More specifically, a bunch of ST M27C512 from the early 90's
* Connections:
* Port A 0-7: low address byte (output)
* Port B 0-7: high address byte (output)
* Port D 0-7: data (input)
stecman / avr_serial_pin_pulse.c
Last active Mar 24, 2018
Hacked together serial-controlled pin power pulser (AVR)
View avr_serial_pin_pulse.c
#include <avr/interrupt.h>
#include <avr/io.h>
#include <avr/wdt.h>
#include <stdlib.h>
#include <string.h>
void init_usart(void)
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