Thursday, October 8, 2020

Reverse engineering my cable modem and turning it into an SDR

This is the type of nerdy hacking that makes me jealous.

After removing a few screws from the plastic housing to get access to the board, my first thought was to look for UART headers to take a peek at the serial console. After identifying two candidates consisting of four vias surrounded by a rectangle near the edge of the PCB, it was time to identify the pins. Using a multimeter, the ground pin can be easily identified by checking the continuity with one of the metal shields on board. The VCC pin can be identified by measuring the voltage of each pin when powering on the board. It should be a steady 3.3v, or in some cases 1.8v or 5v. This pin is not needed, but is still useful to identify the operating voltage and eliminate one candidate for the Tx and Rx pins. While booting, the Tx pin will sit on average a little lower than the VCC pin and drop much lower when a lot of data is being output. This leaves the last pin as Rx.

Tuesday, October 6, 2020

The economics of vending machines

It is estimated that roughly ⅓ of the world’s ~15m vending machines are located in the US.

Of these 5m US-based vending machines, ~2m are currently in operation, collectively bringing in $7.4B in annual revenue for those who own them. This means that the average American adult spends ~$35 per year on vending machine items.

What makes the vending industry truly unique is its stratification: The landscape is composed of thousands of small-time independent operators — and no single entity owns >5% of the market.


Thursday, October 1, 2020

Test if your email is letting the sender know when you view an email

There are a ton of ways companies can track if you view an email.  This site tests which of these methods work even if you are blocking images for example:

You have to click the link in the first email, then click "test this email" for a second email that actually runs the test by the way.  I was confused at first why it wasn't doing anything.