Table of Contents

General Tips

screen /dev/tty.usbserial-A400gw05 115200 >> output.txt
//Ctrl-A then Ctrl-K then y and <Enter> exits

Arduino dumb stuff

Turn on warnings for arduino! It'll catch dumb compiler stuff like this: 

unsigned long a = 500 * 1000; // ~30000
unsigned long a = (unsigned long) 500 * 1000; // 500000

Also default value for int is 2^16

Arduino setup

Name Board Programmer Notes
Pro Trinket Pro Trinket 5V 16MHz USBtinyISP Need to install Adafruit driver for Windows
Arduino Mini Clone (CH340) Arduino Duemolinovae AVRISP mkII Need to install CH340 drivers for Windows
Wemos D1 Mini LOLIN WEMOS D1 R2 & Mini AVRISP mkII I think CH340 drivers too

Projects

Cheap arduino clones at Banggood. Probably don't want an attiny as there's not a lot of flash/ram space. .50 more and a little more real estate to use something more, 328p for example.

https://www.banggood.com/Wholesale-Attribute-Module-Board-c-2152-0-1-3-44-0-s-4662v39801_page1.html?version=1&sortType=asc

Don't need it right now as I have other similar boards available that I can use up. But for future projects…

Bought FTDI header. Cheap.

Buck converter

Cheap at banggood. Can get 3a input and buck/boost for dollars.

https://www.banggood.com/TP4056-Micro-USB-5V-1A-Lithium-Battery-Charging-Module-Board-TE585-Lipo-Charger-p-1225993.html?rmmds=category

https://www.banggood.com/DC-DC-Boost-Buck-Adjustable-Step-Up-Step-Down-Automatic-Converter-XL6009-Module-p-1087346.html?rmmds=detail-bottom-alsobought__1

https://www.banggood.com/DC-DC-8A-Automatic-Step-Up-Step-Down-Adjustable-Power-Module-p-969195.html?rmmds=search

Lots of good tips in this flashlight led recharge li ion project video. Maybe need a fuse though :-)

YouTube Link! https://www.youtube.com/watch?v=0CnhTuoTY2M

Also spot welder with old microwave, maybe batteries.

Simulation

It might be helpful to have a simulator running your chip. For example, if you want to give funky inputs but don't have an extra scope lying around. Ehhh…most people want to test on the hardware itself.

Spark Core Stuff

> git clone https://github.com/spark/firmware
> git checkout latest //(not develop)
> cd firmware/user/applications/
firmware/user/applications> ln -s ~/Dropbox/eng/projects/homerot/spark/homerot/src/ homerot
firmware/user/applications> cd ../../main
firmware/main> sudo make clean all PLATFORM=core APP=homerot program-dfu
SYSTEM_MODE(MANUAL);
bool WiFiEnabled = 0;
 
void loop() {
    if (ConnectToWifiNow == 1 && WiFiEnabled == 0) {
        WiFi.connect();
        WiFiEnabled = 1;
    }
    //Wait until WiFi is ready
    if (WiFi.ready() == 1) {
        //Do sync stuff
        DoSyncStuff();
        //Then
        WiFi.disconnect();
        WiFiEnabled = 0;
    }
}
bool SparkConnect = 1;
if (WiFi.ready() == 1 && SparkConnect == 0) {
    Spark.connect();
    SparkConnect = 1;
}
 
if (WiFi.ready() == 1 && Spark.connected() && Time.now() < 1000000) {
    Spark.process();
    //Spark.syncTime();
    Serial.println("Syncing time");
}
 
if (WiFi.ready() == 1 && Spark.connected() && Time.now() > 100000) {
    Spark.disconnect();
    WiFi.disconnect();
    WiFiConnect = 0;
    SparkConnect = 0;
}

Debugging

JTAG Hardware

I am using a Bus Pirate for debugging because I have it lying around. Bus Pirate pinout,Spark core Pinout (make sure TDO (D4 on Core)is pulled up with 10K resistor!)

Additionally, if your wifi isn't working (optionally, you hear a high-pitched whining from the board), plug in your USB serial cable as you don't have enough power!. It provides the >200mA of current needed for the WiFi chip plus your normal serial connection.

Software

Build your code using make (as normal), but add JTAG and debug flag support: 

make clean //Erase your normal (non-debug) build
USE_SWD_JTAG=y DEBUG_BUILD=y make  //Rebuild with debug flags

Set some stuff for OpenOCD:

mybuspirate.cfg
source [find interface/buspirate.cfg]
#Set serial port
buspirate_port /dev/ttyUSB0
 
# Not really used
buspirate_vreg 0        #turn on voltage regulator
buspirate_mode normal   #or open-drain
buspirate_pullup 1
sparkcore.cfg
# This is a SPARK-CORE board with a single STM32F103MD chip.
source [find target/stm32f1x.cfg]
# use hardware reset, connect under reset
reset_config srst_only srst_nogate

Start up OpenOCD server 

> sudo openocd -f mybuspirate.cfg -f sparkcore.cfg

Open up a Telnet connection to OpenOCD to reset the chip if needed. (soft_reset_halt seems to work better than reset halt) 

> telnet localhost 4444
telnet> soft_reset_halt

GDB

To run, do arm-none-eabi-gdb -x jtag.gdb -tui, then <Ctrl>+x 2 which enables assembly and code view mode. <Ctrl>+x o switches the views. More info here

jtag.gdb
target remote localhost:3333
file core-firmware.elf
set remotetimeout 2000

Use eclipse?

Other OpenOCD commands…

Local Builds

<project-dir> > sudo ../sparky make

To distinguish between the normal spark commands and Spark-Util commands, I've made a local executable of spark-util and called it sparky

Follow Spark-Util instructions for doing multiple projects at once. However, I think you need to reset in between changing projects, which wipes out your build.mk file, so be sure to have a backup.

Added -std=gnu++11 to CFLAGS += in spark/core-firmware/build/Makefile, now static asserts work!

Splitting Up Files

Can't put header and implementation in the same file for some reason. It's saying there's multiple definitions :/

Arduino Stuff

Include a separate library inside of your C++ and H files? It still doesn't work… >.<

Boring but useful tools

Compression

Power Optimization

General Tips

Using μC as USB Slave Input (Human Interface Device)

In Hardware

In Software

Not sure how much easier hardware method using LUFA is compared to software V-USB. Will be finding out soon.

ARM Development

STM32

Long-Term Questions