> For the complete documentation index, see [llms.txt](https://wiki.purduesigbots.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://wiki.purduesigbots.com/software/general/register-programming.md).

# Register Programming

**Register programming** refers to an arcane but frequently necessary method of programming in [embedded systems work](/software/general/embedded-programming-tips.md). Often filled with jargon and insidious details, such programming is best left to experts.

## Gory details

Typical programmers, especially those brought up through a CS education, generally focus on programming at the algorithmic level. However, to make functions work at this level, low-level support routines such as device drivers for hardware must be functional. Embedded systems programming seeks to get this stuff out of the way, and is more frequently taught in electrical and computer engineering courses. An example of what one might see in a low-level driver is shown below:

```bash
// Enable OC1-OC4 as output compare, preload enabled, active then inactive when counting up
// ("PWM mode 1")
TIM4->CCMR1 = (uint16_t)0x6868;
TIM4->CCMR2 = (uint16_t)0x6868;
// Activate OC1-OC4 as active low signals (with the CCMR1-2 settings, this causes a right-
// aligned active high pulse to appear on the output)
TIM4->CCER = (uint16_t)0x3333;
```

This code looks very little like C; most constants are in hexadecimal, most variables have unintuitive names, and familiar constructs such as while loops are distorted to the point of confusion. Since this type of code is seldom self-documenting, good [code style](/software/organizing-code/code-styling-guide.md) dictates a descriptive comment for nearly every line.

### Contributing Teams to this Article:

* [BLRS](https://purduesigbots.com/) (Purdue SIGBots)


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://wiki.purduesigbots.com/software/general/register-programming.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.