Hi! First of all, Happy New Year 2017! I hope all of yours starts the new year with good intentions. The mine one is write frequently here. Family and work don’t let me much free time but I’ll try it!
For several months I’m working with FONA808 modules from Adafruit to make a portable, web-based locating system. This modules are based on the SIM808 module from SIMCOM manufacturer, and integrates both GSM and GPS transceivers in one 24x24mm package. The Adafruit board includes this module and also some electronics for choosing voltage levels, battery connection and charger. Because I need to test and programming some of this modules, I decide to make an specific PCB for it, allowing the programming and debugging via PC, wich is more comfortable that use a microcontroller for all these tasks. I use the MCP2221 USB-Serial bridge and add some electronics to give the board more functionality. So it has a connection for a 3.7Li-Ion battery, battery charger, manual pushbutton to turn on/off the module and also several led’s to indicate the status of the different elements and network connections. So, let’s go for it!
UPDATE: It seems that Adafruit’s people also like know how the things works!
Hi all! Yesterday I was at home and I’ve got on the table a MicroSD adapter. I know, and also imagine, that this kind of adapters are just a contact extension to fit the MicroSD contacts in the SD format. But I need to ‘confirm’ it, so I take the screwdriver to open it, and here’s the result:
This is the adapter that I’ll open and it never will be the same. Once is open, carefully for not break any part, I obtain the three parts that make up the adapter: two plastic covers and the contact extender.
The extender can be removed carefully from the back plastic, and has enough quality for this kind of pieces:
On the MicroSD part, the contacts are folded, and acts like a spring when the microSD is inserted on the adapter:
With this my curiosity is satisfied, at least until I find more things to open 😉
Hi all! After a couple of months with a lot of work, I come here again with the last board I develop before Christmas. It’s a dual USB serial and I2C converter based on two MCP2221Microchip 2.0 USB-Serial bridges. I develop it as a need on my work with the last project I’m involved. I need to monitor a serial communication between two devices. With only one converter, I must choose between RX and TX lines to monitoring the traffic. With this solution, I can listen at the same time TX and RX lines, so the monitoring is more easy. And with a software like Docklight (you can download a free evaluation copy here), you can choose the monitoring option to display both channels. After the break you can find all the technical info of the board!
Hi all! After some time out, due some hard work, I’m here again with a ‘one weekend’ project (in my case, with three childs. Sure it can be done in one afternoon!). I want to start some projects with Arduino and IoT, so the first things I need is an Arduino board, an Ethernet shield and a switch to connect it to the net. Also I need a power supply for the Arduino board, and I think that, better than a external USB AC wall adaptor or power supply, is modify the switch to add it a USB power port that can power the Arduino board. I’ve got at home a TP-Link TL-SF1008D, a simple 8 port 10/100 Mbps switch. So, let’s go to open it and add it the USB port!
Hi all! Here’s the new project where I’m working a couple of days. Since I develop the SIM900 module and test it, I don’t work with it. Also, I’ve got at home some samples of the MCP2200 USB bridge that I want to test it. So make an USB interface for this board was the perfect idea! This allows to use the SIM900 board with a PC, Raspberry or similar, with the plus of no need external power supply or control signals. Just plug the USB cable on the board and start communicating with the world!
UPDATE: Thanks to Rando, now you can order this PCB on OSH Park. Thanks!!
UPDATE: If you’re interested in mount the board yourself, now you can download the Bill Of Materials (BOM). Happy welding!
Hi all! With a bit of delay, here’s my last work, a PICnano breadboard based on the PIC18F2550 microcontroller. I have in mind a new project and I want to use an small board, like the Arduino Nano board. This new project is battery powered (3,7V Li-Ion battery). After checking the schematics of the Arduino Nano, I see that the microcontroler is powered at 5V. Of course, I can unmount the linear regulator (U3) that is on the board, and bypass the VIN to the microcontroller power supply. But I think it’s funny try to develop a new module when you’ve access to the microcontroller power supply! Also, I want to work with PIC microcontrollers after many years, so here’s what I design!
In the last months, I make some boards based on the BeagleBone Black board (three at this time!). In these projects, I only develop the hardware platform, the carrier board where it will be mounted. For the develop of this kind of boards, mechanical information provided by the manufacturer is very important, and enough in the most cases. In the case of the BeagleBone Black board, this info is included in the Reference Manual: BBB_SRM. But I don’t find some interesting distances that I need for my boards, so I take a board, I measure it and here are the results.
In my last projects, I always use the same CPU. DSETA board, I say in the posts. Well, here it is, a CPU based on the AT89C51RE2 microcontroller from Atmel. I develop this board for some reasons. The first and main one is because I want to have a small board with a great (an known) 8-bit microcontroller, ready to use and with many of the peripherals I usually use. The other reason is that I want to test the PCB service from Seeedstudio, a PCB manufacturer from Shenzhen, China. Here are the results. Continue reading →
I develop this MCP23017 Breakout Board to interface a 2×16 LCD display with any microcontroller using a standard I2C bus. Typical 2×16 displays needs at least 6 lines to work (when working in 4-byte mode); in some cases, this will be prohibited for some microcontrollers. With this board, you can control it with only two lines (I2C bus) and, by the same price, obtain a few more IO’s. I use the MCP23017 I2C expander as a bridge. This integrated circuit provides 16 IO’s over a standard I2C bus. All the pins can configure as inputs or outputs independently, and supports high speed I2C (up to 1,7MHz). Also, this device has three hardware address pins that allow connecting up to 8 devices in the same bus. The rest of the features can be seen in the datasheet.
I want to start a serie of brief articles describing the components that I usually used in my electronic designs.The first one is the DS28CM00 I2C serial number. This device is an electronic registration number that gives you an unique 64-bit serial number over I2C or SMBUS interface. This 64-bit serial number is factory lasered, so there aren’t two devices with the same number.
I use this component in a railway application, to identify the PCB’s mounted in the system. The pinout and the typical connection of this device is shown here: