' AoSC - 2021 eChallengeCoins ' ' ' ' ' ' ' '
Sara Cladlow headshot

the Adventures of Sara Cladlow

I am Sara Cladlow, a social consultant working in Washington, DC. I provide consulting, social training, and event services for both corporate and political clients.

The 2021 eChallengeCoin is available on my Tindie store!

So get ready to take on the interactive challenges and the story of Sara and The Brewer's Bible. See if you can spot any clues in the photos below!

More About the 2021 eChallengeCoin

What's New

The new eChallengeCoin has eight touch sensors and eight LEDs. This makes for new challenges. The new puzzle also has a buzzer. The buzzer is not very loud - especially being covered - but it's there and is significant. The IR transceiver has been improved which makes the bonus more reliable. Hackers will even find breakout test points on the PCB for the IR transceiver, but they are not strictly required..

The eight touch sensors and eight LEDs means the 2021 puzzle has 4 interactive challenges. They progress in difficulty and weirdness so don't get mad, get busy! Some old school creativity is warranted.

The eight touch sensors also means there are now four demos. The touch demo is back and now can be used to play music! The SIMON game is back too. The blinking LEDs has been updated to animations. There is even a random number generator so you can use the eChallengeCoin in place of a one to eight sided die.

What's Familiar

The 2021 eChallengeCoin is only 44mm in diameter and is a little over 6mm thick. There are 16 contact pads around the perimeter which means they are small - only 5mm * 2mm. The UART uses the TX, RX, and GND pads. It is set for 9600-8N1. It only outputs line-feed so you may need to configured your terminal to add the carriage-return. The puzzle may be powered using the 3V and GND pads. It will tolerate up to 3.3V.

There are two contact pads near the top of the eChallengeCoin with a 'switch' symbol. Connecting these two pads will wake the puzzle. Connecting these two pads during a demo will put the puzzle back to sleep. You will know the puzzle has recognized the wake is active when all LEDs flash once. Connecting these two pads during an interactive challenge's 'clue' phase will flash the LEDs and then immediately skip to the 'answer' phase and wait for the user input. This may be helpful when attempting a challenge again and it has a lengthy clue.

Some of the interactive puzzles have a long clue. If you already know the clue and just want to skip to providing the answer, you may use the wake pads as previously described or you may touch all of the touch sensors together. You will know the eChallengeCoin has detected this when all of the LEDs are illuminated. Once you release all of the touch pads, the LEDs will go out and the eChallengeCoin will be ready for you to answer the clue.

When the eChallengeCoin wakes, it will show the current status. The status includes which interactive challenges have been solved, which story challenges have been solved, and if the bonus has been achieved. A solid LED means a challenge is completed and the next challenge is shown with a blinking LED. Touching any sensor will leave status mode and begin the next unfinished challenge. The eChallengeCoin will go to sleep after a challenge has been completed or failed. It will also go to sleep if idle for 60 seconds. The idle time is extended to 5 minutes when in story mode.

The interactive challenges use a combination of the touch sensors, the LEDs, and the new buzzer. The layout of the LEDs are from right to left - the right most LED can be thought of as #1 and the left most LED as #8. The touch sensors are labeled with 1..4 on the left and 5..8 on the right.

The eChallengeCoin has another story from the series the Adventures of Sara Cladlow. Within each story, you are tasked with solving the challenges Sara encounters. The story is accessed through the UART connection on the eChallengeCoin.

The demo modes of the eChallengeCoin are activated by touching opposing sensors while waking the puzzle. Once a demo has been activated, it remains active until it is deactivated - even though sleep/wake changes. To return to the challenges, touch any single sensor while waking the puzzle.

eChallengeCoin - New "Skip" Feature

eChallengeCoin - Removing the Backshell

eChallengeCoin - UART

eChallengeCoin - Audio Out

From the Desk of Sara Cladlow

June 12th

Audio Problems

We received a report the buzzer on the 2021 eChallengeCoin was barely audible even after removing the backshell. We tested a few reserve units and were shocked to find they were weaker than when they were originally assembled (which makes no sense).

We know we were forced to make a late hardware change but we tested all units and grouped them as 'good', 'ok', and 'weak' and then reworked the weak ones. (Even our #000 unit is now suffering from the issue.)

There is a workaround. The audio is available on a pad near the bottom of the eChallengeCoin. The output is a microphone level signal. We have added a video showing the audio connection.

Spoiler: The audio is needed for the 2nd interactive challenge. The audio pad was added for the 4th interactive challenge.

June 2nd


A birdie told me, if you get a 2021 eChallengeCoin and attend DEF CON 29 (DC29) in person, you may find it helpful to take your puzzle with you ... just saying.

May 11th

2020 Recap

The 2020 eChallengeCoin was a great success. It was originally a limited run of only 250 but - with a few hardware changes because of the chip shortage - the 2020 eChallengeCoin REDUX is not available on the Tindie store.

twitter instagram