This is a different kind of post, until this moment there is only one post with hardware and as a electrical engineer, I worked with many kind of electronic projects but with the time I forgot to talk about them, or what did developed in the past. So, for this reason I'll show some hardware designs that I developed for personal use and for my company in the moment [AWGES] (I have authorization to publish about this projects).
Bee Mote - 6LoWPAN device for IoT
This project was a 6LoWPAN device module for sensor networks that works in IEEE 802.15.4 specification, this is a two layers board. The target used was CC2650, an ARM Cortex-M3 that is capable to works with many RF protocols as Bluetooth, ZigBee® and 6LoWPAN, and ZigBee RF4CE remote control applications. An alias for this board is the name bee mote what's a reference to the insect that flies and keeps passing a message from him to the others, as in a mesh network. The PCB antenna it's a reference design from TI and it works with 2.4GHz devices.
Some good links for RF layout tips:
- Application Note with many TI designs benchmark
- CC26XX layout considerations
- CC26XX hardware checklist
- RF Front End options and Antennas
- CC26XX Optimal Load Impedance
I've also used this board on my term paper as a proof of concept for 6LoWPAN IoT plataform, if you want to see this board working, just look the video below.
Test board for GNSS - CAM-M8Q and ATmega 328
I projected this board to test a sample module for a product with the u-blox module CAM-M8Q (datasheet here), this module works with three kind of satellites (GPS, Galileo, GLONASS, BeiDou) and it has an embedded Chip Antenna with high sensitivity gain of -167dBm that's omnidirectional and wideband antenna. In this board I've used a ATmega 328p to interface with the AT Modem commands and some external headers to communicate with other IC's.
Central Photon - IoT baseboard for Particle Photon
This is a baseboard for the Particle Photon board, I designed to create a hardware interface for my room sensors that'll be integrated into the cloud, with this approach I could test a lot of resources of the Particle Platform including ifttt integration and cloud deploy firmware development. This baseboard gives to the photon the skills to:
- Control a relay with two outputs (included on the PCB);
- Control 3x Mosfets N-Channel;
- Control a 2.2' TFT LCD;
- Power Jack connector with +12V input for RGB LED Strips;
- 2x Reed switch inputs
- Serial Interface for other microcontrollers integration;
- 3x LED's for status and for information;
I still designed a case printed in my 3D printer for this board, it's simple but looks cool in the night with the LCD 2.2' on top. In the next posts I'll do something cool about integration with this board and IoT sensors, keep accessing the blog in the next weeks.
ESP8266 Dev. Board - A development board for ESP
In 2014 I started studying the ESP8266 Chip, it was the first cheap Wi-Fi module (compliant IEEE 802.11 b/g/n) available in the market until that moment and working with it, I realized that would be important to have some way to test all characteristics that the SDK's released by Espressif. For that reason I developed the ESP8266 Development Board, a simple board that could supply all needs to play with this Chip. This board has great features for who search to start in the ESP8266 world as:
- 1x Relay Output 5Vdc/10A~250Vac
- FTDI32 Serial chip integrated
- 1x Push-button
- 3x LEDs
- 1x Buzzer/PWM
- Connector for interfacing with I2C
- Regulator for external supply
Driver for LED Matrix - 12x16
This project was designed a long time ago to play with a FPGA (Spartan-3E - Basys 2) and it's a simple driver for a matrix of 192 LED's (12x16), it works with a daisy chaining mode, where I pass all information in a serial-way mode, the process to write something in the matrix is very simple, put a 12-bit parallel data in the input and after keep clocking it to turn on the other LED's that's in the sequence. The only reason to use with a FPGA is that to drawn an image, you need speed in the clock signal and 12-bit input changing.
As an example:
For 30 FPS ~> 1 second / 30 frames = 33,33ms (each image)
33,33ms/16columns = 2,08ms ~ 500Hz
What means that we need to generate a 500Hz clock signal for the daysi IC what's very slow for a FPGA, but you need to sync the 12-bit parallel for each column with the clock signal and the 500Hz situation is to display each frame one time (33,33ms ~ just 1 frame per time) however we usually work with 100x a frame show to see a good quality of lighting, what ends with 50kHz for the clock + the 12 input bit sync (Now FPGA like Spartan-3E is a good approach).
I have some other projects to share but for the moment this is good and if you want some schematics, just comment below and I'll shared you without NDA.
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