![[Flipper Zero] ditching the Raspberry Pi, making our own board from scratch. Finding the Right WiFi Chip](https://prohoster.info/wp-content/plugins/wp-fastest-cache-premium/pro/images/blank.gif)
is a tamagotchi pocket multi-tool project for hackers that I'm developing with friends. Previous post .
A lot has happened since the first post about the flipper. We have been working hard all this time and the project has undergone a radical change. The main news is that we decided to completely abandon the Raspberry Pi Zero and make our board from scratch based on the i.MX6 chip. This greatly complicates the development and completely changes the whole concept, but I'm sure it's worth it.
Also, we still haven't found the right WiFi chipset that supports all the necessary features for WiFi attacks while supporting the 5Ghz band and is not out of date by 15 years. Therefore, I invite everyone to participate in our study.
In the article I will tell you why we made such a decision, at what stage the project is, current tasks, and how you can participate.
What is wrong with Raspberry Pi Zero
I personally love the Raspberry Pi, but during the development process it turned out that it sucks for many reasons. The most banal - you can't buy it stupidly. Even big distributors have no more than a couple hundred rpi0s in stock, and stores like Adafruit and Sparkfun sell no more than 1 per hand. Yes, there are several factories that produce rpi0 under license from the Raspberry Pi Foundation, but they also cannot ship batches of 3-5 thousand pieces. It looks like rpi0 is being sold at a price on the verge of cost and is more aimed at popularizing the platform.
Here are the main reasons for abandoning rpi0
- Cannot be bought in bulk. Factories like Farnell offer to buy the Compute Module. The Chinese with Alibaba lie about the presence of large volumes, when it comes to a real batch, they merge. To everyone who writes that we werenβt looking well, try to negotiate with someone to buy 5 thousand pieces, so that they send you an invoice for payment.
- Few interfaces.
- The old BCM2835 processor, which was used in the first version of rpi. Hot and not very energy efficient.
- No power management, can't put the board to sleep.
- Outdated built-in WiFi.
- and many other reasons.
The Raspberry Pi Foundation itself suggests using the RPi Compute Module for such tasks. This is a board in the form factor of a SO-DIMM module (like RAM in laptops), which is inserted into the motherboard. This option does not suit us, as it greatly increases the size of the device.
Raspberry Pi Compute Module - SO-DIMM form factor board for installation in your device
Then we started looking at different SoMs (System on Module), i.MX6-based modules looked the most attractive. All our searches are described in a topic on the forum. But you need to keep in mind that not all companies will be ready to work with you with volumes of even 3-5 thousand pieces per year. For example, the Israeli Variscite simply stopped responding to us when it found out the planned volumes of purchases. Apparently, they are not interested only in selling SoMs without additional services in the form of support and integration. Separately, I want to note the Russian developer , which make very interesting devices, like . They are almost impossible to google, and I would not have known about their existence if my acquaintances had not told me.
In the end, after comparing all the options and estimating the economy, we made the difficult decision to make our SoM from scratch specifically for Flipper based on a chip . It's a single core Cortex-A7 at 900 MHz with almost the same performance as rpi0, but it's almost cold under load, while rpi0 is hot as hell.
By making our board from scratch, we have complete freedom in the arrangement of elements on the board, which is why we expect to get a more compact device. i.MX6 ULZ is a stripped-down version of i.MX6 ULL without some interfaces and video core, so for development we use the MCIMX6ULL-EVK development board with the i.MX6 ULL chip, just not using some of the interfaces. This board, by the way, is supported by the mainline linux kernel, so Kali Linux is loaded on it with the kernel from the packages.
Here's what the flipper looks like without clothes at the moment:
Proper WiFi
WiFi hacking is one of the main features of Flipper, so it is extremely important to choose the right WiFi chipset that will support all the features you need: packet injection and monitor mode. At the same time, be able to use the 5GHz band and modern standards like 802.11ac. Unfortunately, such chips could not be found immediately.
Chinese SiP module (system in package) Apmak AP6255 based on BCM43456
Now we are considering several candidates, but all of them require finishing and it is not yet known which one is better to choose. Therefore, I kindly ask everyone who understands the WiFi trick to join our search here:
Main candidates:
- Broadcom/Cypress BCM43455 or BCM4345 with patched firmware.
- Mediatek MT7668 - not yet tested, but in theory it may be suitable.
Please, before advising something, carefully read the requirements on the forum, including the connection interface. Remember that I have been carefully studying this topic for several months and have already shoveled everything that can be found.
What's already done
The whole part for which STM32 is responsible is already working: 433Mhz, iButton, reading-emulation 125kHz.
The mechanical part, buttons, body, connectors, layout are now in active development, the video and photos below show an outdated body, in new versions the joystick will be larger.
The video shows a simple demonstration of opening the barrier using the remote control signal replay.
FAQ
How to buy?
Presumably, we will launch a crowdfunding campaign on Kickstarter in April-May of this year. We hope to send the finished devices six months after the completion of the collection. If you are interested in the device, please leave your email below , we will send offers to subscribers when prototypes and early samples for sale are ready.
It is legal?
It's a research tool. All of its components can be purchased separately in the store. Putting a WiFi adapter and a 433MHz transmitter into a small case and adding a screen to it doesn't make it any more illegal. The device does not fall under the definition of special. means or device for secret collection of information. It can ONLY be illegal to use it for the purpose of causing damage or for illegal activities. In other words, I can make knives of any shape and from any metal, the responsibility for the use of my knives lies with you.
How to donate?
For now, you can personally support me with a small food donation through . Regular donations of $1 are much better than a large amount at a time, because they allow you to predict ahead.
I publish all project notes in my Telegram channel .
Source: habr.com