While reverse-engineering the firmware on the Digoo DG-HOSA device which I have a couple of posts on already. I ran across some memory addresses that did not directly map to peripherals. I found the address ranges are called the Bit-band range and had special functionality allowing direct access to individual bits on peripherals. This post will give a quick summary of what these addresses are and how to unmap them to the normal peripheral addresses.
This is a continuation from a previous post: https://ben.the-collective.net/hugo/posts/2019-08-21-digoo-dg-hosa-part-1-teardown-and-hardware/ Finding the connections Now that I have the lay of the land for the device (which that I outlined in my previous part of the series) the first thing I looked for is the debugging connections for the main GigaDevices processor. This processor looks to be the primary processor for the device and has the most valuable firmware. Since the board was well labeled I didn’t need to use any tools like a JTAGulator or an Arduino board with the JTAGenum firmware to identify which test points are the debug interface.
This project started with the idea of purchasing a cheap security system off one of the Chinese stores. After a little hunting, I found Digoo DG HOSA 433MHz 2G&GSM&WIFI Smart Home Security Alarm System Protective Shell Alert with APP which looked interesting so picked one up to tear apart. I was curious about how various communication methods were implemented. This is the first part of this adventure the next part will be exploring the firmware of the device.
This post is some free-ish form notes about a project that is either work in progress or complete. Description This project is a small sensor to monitor Temperature, Humidity, and Light levels. The project may end up in a toy Star Trek TNG Tricorder case at some point in the future, but I wanted to document where it is at a today. Originally I used an Adafruit Huzzah (ESP12) board, but after I determined I wasn’t going to use the wifi, I switched to the Adafruit Adalogger board.