greghgradwell / 1_hardware_vs_software.md

Last active April 9, 2021 15:36

1. Hardware vs. Software

Software is great, but at some point it has to interact with hardware or it's useless. One of the pressing questions early on was how many of the hardware interfaces could be written in Elixir. For example, the first peripheral I wanted to test out was an IMU (inertial measurement unit). If I were working with Arduino, I would have a library already available, ready to plug and play.

Should I connect the IMU to an Arduino board, and then interface with the Arduino board using a serial protocol of my choice? Or does the extra hardware outweigh the benefits of ready-to-use software?

Since I was still very new to Elixir, I thought it would be interesting to replicate one of my previous projects that had utilized Arduino, in this case a 2-axis camera gimbal. Do I have pictures of the original? No. Did I take pictures of the Elixir version before I took it apart? Also no. So we'll have to use our imaginations. (Don't worry, I hear your boos and I agree)All I can offer i

greghgradwell / 2_code_for_any_mode.md

Last active April 9, 2021 15:53

2. Code for any Mode

From the start, this autopilot was designed to use multiple nodes operating on a local network. And with that premise in mind, I introduce you to Segal's law (not to be confused with Steven Seagal's Above the Law).

₁

"A person with a watch knows what time is it. A person with two watches is never sure."

And here lies perhaps the biggest issue when it comes to multiple devices working together:

If two devices disagree, how do you know which one is right?

I'm sure there's a lot of really clever answers to this, but the nature of Elixir allows for an answer that is simple. And I like simple.

If a device is alive, assume it's right.

greghgradwell / 3_commands_on_demand.md

Last active April 9, 2021 16:54

3. Commands On Demand

3. Commands on Demand

Welcome back! Unless you never left, in which case, maybe it's time for a snack?? Previously we were discussing the notion of taking two sources of hardware output and somehow rectifying them into a single software input. I used the example of two IMUs, but I'm going to retract that one for now, because I haven't actually duplicated sensors on the vehicle yet. Rather, let's talk about using multiple sources of vehicle commands, since I've at least got that much working. But 2021 is the year of redundant sensors! (or should I call them oxiliary?)

Pesky front seat drivers...¹

Two is one

I've never tested an autonomous system that lacked the option for a human operator to assume manual control. I know there are aircraft out there where the pilot is l

PJUllrich / big-o.md

Last active February 13, 2025 23:48

Big-O Time Complexities for Elixir Data Structures

Big-O Time Complexities for Elixir data structures

Map [1]

Operation	Time Complexity
Access	`O(log n)`
Search	`O(log n)`
Insertion	`O(n)` for <= 32 elements, `O(log n)` for > 32 elements [2]
Deletion	`O(n)` for <= 32 elements, `O(log n)` for > 32 elements

sachinsmc / tophnpost.md

Last active December 15, 2024 11:46