Álvaro Prieto
@alvaroprieto
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Electrical/Firmware Engineer, maker, traveler. @unnamed_show co-host.
San Francisco, CA
Joined November 2009
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Latest project: 7400 Series digital clock! Based on my dad’s college project from a long time ago
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Ever wonder if your USB C cable is USB2 or USB3? Do you have some charge-only cables hiding in a box just waiting for the right moment to spoil your project plans?!
Fear no more!
I’ve made a simple board to test most of the things!
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Ever wanted to debug your microcontroller over USB-C?
(I'm talking JTAG/SWD, not just USB!) If you already have a USB-C connector, there's no need to have an additional connector to program (or tag-connect pads, which are super nice)
Here's one way to do it: 🧵
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A few days ago, I found my dad’s college Digital Systems project notes. The task was to build a clock with 7400 series logic.
I decided to try and re-create the project with components we bought together many years ago.
I’ll do a quick thread explaining how it all works
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Two weeks to re-watch seasons 1-3 :D
Back to where we started. Castlevania Season 4 streams May 13th
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Best part of all? It’s open hardware! If you want to make your own, here’s the kicad project:
I made a few, so if you know me and want one, let me know :)
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Connect your cable to both sides and the signal LEDs will light up if they are connected. Here’s an example of a USB2 cable and a thunderbolt 3 cable.
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Wanted to make your own game controller that works on iOS? You probably ran into issues since Apple requires them to be MFi certified. There is a way though! No jailbreak required ;)
Here it is running on my iPad with IPadOS 15.5. I’m using a Teensy LC for it.
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If you want to make it yourself, I've added gerbers, BOM, and assembly files here:
Should be pretty easy to order from
@JLCPCB
:D
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But….What if my cable is too short!? We have that covered too 😂
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Here’s what a the dreaded charge-only cables look like. I had to make my own since I had previously banished them from my lab!
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Want to test a USBA to C cable? How about a USBA to MicroB? USBC to B? MiniB? You’ve got it!
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Ever needed to measure a device's low power states (µA or nA level) while being able to flash/debug over SWD?
Ok, probably not... If you had, you would have probably noticed the extra 30-300µA (or more!) drawn by just having a debugger connected (even when not active!) 🧵
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Today was my last day at work. I’ve decided to take a long break to focus on catching up with friends and family, working on personal projects, and traveling. I don’t have any specific plans just yet, but looking forward to the time off :D
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Inspired by
@sophywong
's
#31DaysofFusion360
(and
@GregDavill
's KiCad advent calendar of making!). I'm going to try the same but with
@FreeCADNews
:D
We'll see if I can actually stick to it... Today's model is a LoRa module that's in one of my projects.
#31DaysofFreeCAD
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New board to power most of my devices using USB-C PD power supplies :D
This way I’ll only need to carry one power supply to charge my phone, laptops, etc...
Voltage/current settings are set by the resistors on the back. 5-20V 0-5A. It’s using a Cypress CYPD3177 for the PD stuff
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So
@Chris_Gammell
mentioned my home storage/inventory system on
@TheAmpHour
a few weeks ago hoping I'd make a video about it... Finally got around to it this week. Doesn't cover everything, but hopefully can give you some ideas about your own lab!
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Fridge not working.
Step 1: open fridge.
Step 2: Remove controller board.
Step 3: Solder programming header and figure out pinout.
Step 4: Dump firmware using avrdude and buspirate
Step 5: Start questioning myself
Ste....
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When it’s late and things aren’t working 😬
(They’re working now)
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I’ll be at
#opensauce
all weekend. Stop by and say hello if you’re around! (Or if you need something fixed!)
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The USB-C specification() has a section B - Debug Accessory Mode. It explains how to "support" DAM. In short, if both CC1 and CC2 are pulled up (usually, only a single one is) a device can enter DAM. While in DAM, the following signals can be repurposed:
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Got a chance to stop by
@GSGlabs
today :D
Expect another great
@unnamed_show
episode about USB RE with
@ktemkin
and
@Qyriad
in the near future! (Once I get around to editing it...)
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Latest cheese cave controller PCBs have arrived. Now in yellow!
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New SWD over USB-C board!
✅ 1.6mm PCB
✅ Slightly wider board for easier assembly (and hopefully some sort of case/enclosure)
✅ New USB-C plug that’s (slightly) easier to hand assemble
✅ Flipped pinout on plug, making it completely useless
🤦♂️ 🤦♂️ 🤦♂️
Check your footprints!
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New batch of USB cable testers arrived! After terrible yield issues with the last batch, I changed to use 0.8mm PCB instead of the standard 1.6mm. 95% yield! (100% after a small rework)
If you want to get your own, check out the release and ordering info:
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Had a blast at
#ccccamp19
this week!
Here’s a few of us on our extremely well planned and definitely not winged train ride home :D
Looking forward to the next one!
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First double sided reflow at home.
Connectors lined up!
:D
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If we chose to go this direction, the footprint/component requirements to do this are zero! You'll still need an adapter board to connect your debugger, but that's it! (Maaaaybe I'll start selling these soon if there's any interest)
Hope this was useful! :D
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@MalwareTechBlog
@Fox0x01
has a great ARM assembly series:
No need to re-invent the wheel :D
(Unless you’re not trying to do ARM of course)
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Just recorded another
@unnamed_show
podcast in the ferry with
@joegrand
and
@gareth__
!
I have two others from
@Toorcamp
that should go out in the next few weeks :D
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Put together my latest weather station board!
Now more integrated!
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Any Bay Area friends want to try some homemade Brie? (Assuming I can get it to you)
There’s a few extra wheels that were meant to share with friends, so I figure I can distribute some of them around so folks can enjoy(hopefully) them at home!
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Apparently TDI International is too cool to sell me their tweezers. (I’ve used them at work)
Anyone have good recommendations for alternatives? Mostly for smd work at home (0201s and up!)
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New toy arrived yesterday!
I’m a huge fan of the original
@joulescope
. Looking forward to trying out the new one :D
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TIL my cheap digital calipers measure about half the distance when the battery is low 🤦♂️
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I turned off my soldering iron this morning and noticed something strange...
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@pdp7
Finally finish this project I’d been thinking about for over a decade:
Latest project: 7400 Series digital clock! Based on my dad’s college project from a long time ago
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Made some bread and brought it to work so folks could try the homemade Brie :D
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DAM doesn't specify any standard pinout. It's up to the designer to figure that out. Here's what I came up with:
RX1- - SWDCLK
RX1+ - SWDIO
RX2- - SWO
RX2+ - NRST
SBU1 - VCC(target)
SBU2 - GND
USB D+/D- stay connected the usual way.
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First actual weather station install :D
We’ll see how long it works for...
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Had to run to the airport before the
@hackaday
#superconference
finished. Awesome seeing everyone! Can’t wait for the next one :D
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Made a simple calculator for my usb-c-power project to figure out which resistors to use for what settings.
Looks awful on mobile... which is why I'm going to stick to doing easy things like firmware/hardware instead of HTML/CSS. :/
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I decided to make a test target with all these features. It's just an STM32L4 😎 with USB and a couple of LEDS (along with all the CCx detection fun). You can see how the LED is red when it's plugged in backwards.
After much pain soldering on those USB-C connectors, it all works!
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Cheese making time! Going to try the sous vide instead of stove heating to see how it goes…
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New year, new cheese! Going to try and make a Mont d’Or this time.
😬😬😬
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Got the
#KiCon2019
badge up and running.
NOTE: The white USB cables that came with the battery pack seems to be charge-only, so it won’t work for programming.
@Chris_Gammell
dropped off a bunch of micro-usb cables by the
@digikey
area
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New weather station board is now outside and working!
It’s overcast today, but the battery is already charging :D
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I decided to make a board that passes through power and USB, but hijacks the CC1/CC2 lines to enable DAM. I used an attiny24a(in stock!) to read in the input CCx lines to determine the input charge currents and set the appropriate downstream CC1/CC2. I used the wrong footprint 🤦♂️
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Made my first 3d part model for KiCad using FreeCAD! I should have picked a simpler one to start with, but got it working eventually :D
(Source drawing for reference!)
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Normally, CC1/CC2 are used to determine orientation as well as power delivery information. For this thread, I'll just focus on "dumb" PD with termination resistors. Depending on the source's pull up resistor (Rp) value, the source can advertise various charge currents.
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Before I continue, a quick shoutout to decoupling capacitors. They do wonders minimizing electrical noise (random glitches!) on your circuit.
It’s easy to forget to add them while prototyping, but just compare the first two scope captures to the last one, which had them.
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The project starts with a 555 timer to generate a 10kHz clock source using two resistors and a capacitor.
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Just spent an hour debugging an issue caused by the voltage drop because of cheap cables. Fixed by changing to nice ones.
HiLetgo ??? - $7.49 for 3 pairs. ~1.67 Ohms through both.
Pomona 3782-24 - $15 a pair. Total resistance through both ~0.12 Ohms
You get what you pay for🤦♂️
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In order to do this "properly", we can use a two comparators(op-amps in my case), an AND gate, and a switch (TMUX1511, in this case). The comparators detect when both CC1/CC2 are pulled up. If both are, the AND gate enables the switches to connect all the signals.
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Latest rev of my weather station board. Going to try out LoRa this time. Also split temp/humidity from pressure sensors since I’ve had issues with the BME280 and condensation. The SHT31 has a special membrane to protect it from that. I’ll have to protect BMP280 some other way.
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🤦I should probably show the block diagram first.
In summary, we start with a 10kHz clock and divide it down by 10 until we have a 1Hz clock. From there, we have second, minute, and hour counters, display drivers, and 7-segment LED displays.
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One day until I fly to Germany for CCCamp! :D
Who else is going?!
I should start packing...
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In order to test all this, I first used a USB-C plug breakout board with a few wires 😬
On the other side, I hooked up the circuit mentioned above. (I can't show the main circuit, unfortunately).
The setup worked though! Time to make some custom boards :D
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Looks like I will be going to
@defcon
after all!
I’ll bring my recording gear for some
@unnamed_show
episodes :D
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USB-C cables only pass through CC1. In order to use DAM, we need to have a USB-C plug (or custom cable) to connect both CC1 and CC2. If the device is in DAM, how do you know the charge current? There's another table for that :D
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New weather station prototype is working! Finally got wireless boot loader working so I can program the unit outside :D
Still have plenty of testing to do and a lot more mechanical/weatherproofing work.
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Finished my t-shirt quilt/blanket today! Took way too long but learned a ton about sewing!
I used a fleece blanket for the back.
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So I made another programmer over USB-C 😂
This one uses SPI instead of SWD. I also got the MISO/MOSI lines flipped, so had to use some jumper wires to program.
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Ok, so back to why I didn't want to make the pinout reversible. Following the USB spec is nice and all, but for hobby projects... 🤷
What if we ignore all of the CCx detection stuff and just permanently wire the SWD lines to the USB port? Saves us several components and space!
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Started another batch of cheese yesterday! This one should be closer to a triple cream Brie if everything goes to plan...
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I don’t usually post my bread photos on here, but I’m pretty happy with how this porridge loaf turned out :D
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I hard-wired the CC resistors and it worked :D
Here's the fixed version. It uses the SBU1/SBU2 signals (VCC/GND) to light up a green or red LED to let you know if it's plugged in wrong. It has standard SWD pins for debugger. The only problem is... I have to program the attiny24!
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Weather station progress:
It all fits and seems to work :D
~110uA average current (1 min sampling period) isn’t too bad either :D
Next step is to leave it outside for a while and hope it stays alive. (And future out where/how to mount the solar panel...)
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Backing up old files and running into wonderful directory structures like this one: "old/backup-12-2-07/backup2/ooold/NewBackup/OldBackup/"
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For some context see
A few days ago, I found my dad’s college Digital Systems project notes. The task was to build a clock with 7400 series logic.
I decided to try and re-create the project with components we bought together many years ago.
I’ll do a quick thread explaining how it all works
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Here’s a quick video of the clock working. I change the clock source from 1Hz up to 10kHz to speed things up a bit :P
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This pinout means that the connector is not reversible. Using the TX and RX lines in a particular way would allow for that, but I chose not to do that (I'll explain why later.)
Technically speaking, a device should not enter DAM unless CC1/CC2 are both pulled up.
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Early prototype of weather station project box.
Oversized battery, case, off the shelf regulator and solar charger, and wiring mess.
Goal for the break is get fw/sw/hw working and make smaller, better, and more integrated system after that.
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