Archive for the ‘Microcontrollers’ Category.

Simple Rh, T and p sensor with UART communication

The Pressure, temperature and humidity sensor based on MS5637 HDC1080 originally (Rev. 2) operates via RS485 interface and multidrop HDLC-like protocol.  I decided to simplify this for use with Raspberry Pi, arduion or any other mass platforms. First, I took away the RS485 transceiver and second, I simplified the communication.

First adaptation was easy:

Remove RS485 driver and connect Rx/Tx to A/B

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Pressure, temperature and humidity sensor based on MS5637 HDC1080 Rev.2

Gal ordered some PCBs from PCB-Way a while ago. It was multiproject panel with several PCBs. One of the modules was double sided revision of the Pressure, temperature and humidity sensor based on MS5637 HDC1080 which was posted while ago.

Pressure, temperature and humidity sensor based on MS5637 HDC1080

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Call URL with keypress on Raspberry Pi

Here is scenario:

pushbutton is connected to Raspberry Pi GPIO pin. Whet button is pressed, R.pi calls remote URL.

This can be useful for many simple applications, like detecting and timestamping passes at certain location.

The R.pi should be up and running. Connect the pushbutton to free GPIO. In our example we connected the button to pin 11. The pin is configured with the pullup, which means the button must pull the GPIO pin to ground. Pin 12 on r.Pi model 2B (40 pin P1) is GND:

Ultra simple schematic for this example

Now prepare some simple script on your fancy web browser, which will be called when someone presses the button. Here is example, which simply adds one line with time and date at the end of the file “log.txt” every time when file is loaded:

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Quadruple BDC motor driver for robotics

Once finished (deadline is end of January) this project will become open-source software and hardware.

My quadruple BDC driver for supports up to 4 brushed motors with encoders. Each motor is controlled by its individual closed loop and individual PID gain settings. Additionally, motor speed can also be individually addressed. Analog part of the driver is based on DRV8701P predriver and is controlled by STM32F4 microcontroller.

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LED Xmas tree

Ina soldered today 16 leds in matrix and then we connected it to “LED Decoration” hardware. The basic idea was:

4x4 LED matrix Xmas tree

4×4 LED matrix Xmas tree

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LED decoration

This LED decoration is for beginners in microcontroller applications. It has 8 LEDs, audio generator and possibility to interconnect with other modules. The PCB is simplified to certain level in order to be manufacturable on a single sided substrate with minimum effort. There are only two wire bridges and one 0 ohm resistor in addition to other components. The LED decoration can be used in school projects or for new-years fun. Of course it’s not limited to X-mas tree. It can be used during Bodhi Day, Hanukkah, Id al-Adha, Winter Solstice celebration, Saturnalia, Yule, Kwanza, Omisoka or any other occasion which might come at the end of the year, when day is short and some LED blinking device might rise your mood.

The concept of this LED decoration:

LED decoration concept

LED decoration concept

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APA102C LED strip at 28 MHz clock

I recently received 1m of APA102C led strip with 144 leds per meter. I want to use the strip for rotary POV display so I cut the strip in half and tested the performance with a STM32L476RGT nucleo board. The results of the tests are surprising and very promising for my application.

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Affordable pH meter

Our home vineyard delivers about 1000 liters of wine every year. It takes some effort to keep good quality and pleasure for all friends tasting the must, new wine and “senior” wine reserves. One of the most important tasks in wine quality management is controlling the biological and chemical state of the wine. The wine can be monitored in special laboratory or in home lab. Of course home lab become rational when quantity of the wine is high enough to justify expenses in special equipment.  There is some low cost equipment available for wine analysis, mostly with titration techniques, but chemical lab equipment is rather expensive and many hobby wineries avoid buying such equipment. I hope this post can contribute a bit to change that. I will describe the development of simple pH meter in detail.

IMG_6366.jpg    IMG_0855.jpg

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USB/RS485 converter on a double sided PCB

USB/RS485 module on a single sided board worked successfully for several months. The code is now stable and I decided to order small batch of double sided PCBs for this project. Here is documentation:

RS485/USB interface on a double sided board

RS485/USB interface on a double sided board

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