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I got distracted and had a hack on using a STL Link v2 clone as a development board. There’s a lot to like: A Cortex-M3 STM32F103C8T processor with 64 KiB of flash and 20 KiB of RAM 4 I/O lines and a LED to blink Decent support in STM32duino with a DFU bootloader Comes in a case and plugs directly into a USB port ~$2/each The I/O is strange and limited but it’s enough to drive a RGB LED via PWM, drive a 40 RGB LED pHAT over SPI, and drive a 320x240 LCD over fast bitbanged SPI.

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I’m hacking on adding SDHC over SPI block device support to the Zephyr Project RTOS. I’m currently getting 224 KiB/s on an Arduino Zero with a 4 MHz bus and 1 KiB read size, which is an OK-ish 46 % of the top bus capacity. Here’s where the time goes: 4550 us - total time to read 2x 512 byte blocks from the card 80 us - time spent in ELM FS (impressive!

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I’m hacking on adding Arduino Zero support to the Zephyr Project at the moment. I had a look at speeding up crc16_ccitt() but ran into a problem: there’s so many variants of CRC16-CCITT to choose from! Zephyr uses CRC-16/AUG-CCITT which is equivalent to CRC-16/CCITT-FALSE with two zero bytes prepended. The effective seed is 0x1d0f and test vector output is 0xe5cc. Mynewt uses CRC-16/XMODEM. The seed is 0 and test vector output is 0x31c3.

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There is an issue when trying to program a SAMD21 like in the Arduino Zero using OpenOCD with a ST-Link v2 which gives errors like this: ** Programming Started ** auto erase enabled Info : SAMD MCU: SAMD21E18A (256KB Flash, 32KB RAM) Error: Failed to erase row containing 00000000 Error: SAMD: failed to erase sector 0 Error: failed erasing sectors 0 to 0 The issue is that NVMCTRL_CTRLA is a half-word register and the ST-Link v2 emulates the half word write using two single byte writes.

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In follow up to my mysensors.org build, I’ve always wanted to design PCB and try my hand at SMD soldering. I normally use veroboard on a 0.1” pitch but the time to cut and solder wires makes for a slow build. Here’s the result: It has: An AT91SAMD21E18 (256 KiB flash, 32 pins, 0.8 mm pitch) USB, regulator, Cortex SWD debug header, LED, and pullups on I2C Footprint for a RFM69CW radio Adafruit Feather form factor Two layer PCB with 0603 passives The soldering turned out well.

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Projects

C++ in 2017

Seeing how C++17 compares to Go

spdbt

A fast indoor mousebot

pipoint

A rover tracking camera

Citizen

A balancing robot written in Go and running on ARM Linux.

Ideas

Ideas for future projects.

Others

Some things I’ve hacked on.

PL/0 implementation

A toy compiler for the PL/0 educational language.

Templates

Markdown templates for project plans, etc.

nppilot

The Never complete; often never started autopilot.

ser2neo

ser2neo makes it easier to drive a NeoPixel ring

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