STELLARIS-UEXT adapter for Stellaris launch pad in stock


STELLARIS-UEXT is Texas Instruments Stellaris Launchpad to UEXT adapter.

We have prepared demo code for MOD-GSM, MOD-MP3, MOD-GPS, MOD-TC, MOD-SMB380, MOD-IRDA, MOD-LCD3310 so you can interface these modules from your Stellaris Launchpad.

As Stellaris MCU have two SPI, I2C and UARTs we made the adapter with two separate UEXT connectors so you can connect two independant UEXT modules to it. Each UEXT have power up/down control with MOSFET so you can power up and down UEXT modules connected.

Raspberry Pi GPIO to Breadboard and UEXT adapter


Raspberry Pi is the most successful embedded Linux board for all times, according to their blog they have sold over 500 000 pcs, although when they post something on their blog you never know it’s true or not from our own source we know Farnell and RS Components have sold at least 100 000 each by August this year, so the number may be not exactly 500 000 but still in 6-digit range.

I will admit that our OLinuXino Linux boards were inspired and designed due to the lot of e-mails and requests from customers of ours at the beginning on 2012 when Raspberry Pi had problems to arrange their production. We were asked again and again please do small low cost Linux computer, although at that moment we were just Linux users but never dealt with Kernel compilations, Device drivers build etc. this is what triggered us to go in this direction.

So if there was no Raspberry Pi there would not be OLinuXino as well, I admit it 🙂

Despite all problems Raspberry Pi had with the manufacturing start-up they now have sorted out their production problems and schematic mistakes, so the latest model-B works fine according to what we hear. I asked today friend of mine to borrow me one Pi to experiment with and this on the picture above is what we made.

We all know that Raspberry Pi $35 price is hard to beat, but looking at the additional accesoaries and boards which are sold for Raspberry Pi I can’t say the same for them.

To use Raspberry Pi to interface real world you need additional hardware and the prices of this after sale accessories are quite high, probably to adjust the not-so profitable Raspberry Pi sale price?

For instance the Gertboard which contain few ICs and components + blank board which harly cost more than $10 for the Raspberry Pi volumes is offered for $46!

The new PiFace board with two relays and 4 buttons announced price is $36.

What we did today is small Raspberry Pi GPIO to Breadboard adapter with UEXT on it.

We called it RPI-UEXT and will have these in stock in 2 weeks, what you can do with this breadboard adapter? Well this is basically same T-shape board as our AVR-T32U4 Arduino like breadboard board:

You can see it how it plugs to normal Breadboard here:


The T-shapped boards was first invented by Ken Segler and we used for DuinoMite-TBA.

Every breadboard have two power supply busses on the top and bottom and there we run +5V/GND on top and +3.3V/GND on bottom. With the T-shapped board you make power supply available for breadboarding not only the GPIOs.

On top of the easy for breadboarding adapter we also have UEXT connector, what you can connect to Raspberry Pi with UEXT?

1. MOD-IO2 board which cost EURO 12.95 and adds 2 relays + 7 GPIOs, you can plug together as many MOD-IO2 as you wish as they are addressable so you can have as many relay outputs driven by Raspberry Pi as you want.

The project for MOD-IO2 interfacing with iMX233-OLinuXino is on GitHub and we will release Raspberry Pi pack which will have MOD-IO2 control with Raspberry Pi

2. MOD-IO board which cost EURO 25.95 and have 4 relays + 4 opto isolated inputs + 4 Analog inputs, you can plug together as many MOD-IO as you wish as they are addressable so you can have as many relay outputs and analog inputs + optoisolated digital inputs driven by Raspberry Pi as you want.
The project for MOD-IO interfacing with iMX233-OLinuXino is on GitHub and we will release Raspberry Pi pack which will have MOD-IO control with Raspberry Pi

3. MOD-RTC cost EURO 4.95 is real time clock with battery backup which you can connect to Raspberry Pi with the UEXT adapter

4. Four different LCD modules are available from 1 row 9 characters segment LCD×9/ for EUR 6.95, NOKIA 3310 module 84×48 pixel LCD  for EUR 6.95, color Nokia 6610 LCD 128×128 pixels with backlight and LCD 4.3″LCD module”/ for EUR 79.95. All these modules have GitHub projects for iMX233-OLinuXino which will work on Raspberry Pi also.

5. RFID readers for 125 Khz and 13.59 Mhz which cost EUR 25.95 and allow you to build access control with Raspberry Pi

6. Bluetooth module for EUR 19.95

7. WIFI 802.11n 150MBit RTL8188CU module for EURO 7.95

8. Zigbee module MOD-ZIGBEE-UEXT for EURO 17.95 which allow you Raspberry Pi to connect and control Zigbee network

9. Zigbee PIR module which cost EURO 18.95 and allow Raspberry Pi to detect movement via Zigbee network

10. Quad band GSM/GPRS module for EURO 49.95 which allow Raspberry Pi to send and receive phone calls, GPRS data and to send and receive SMS

11. GPS module which cost EURO 29.95 and allow Raspberry Pi to log your GPS coordinates

12. Wii Nunchuck joystick which cost EURO 6.95 and adds 3-axes accelerometer, XY joystick and 2 buttons so you can control your Raspberry Pi Games

13. Digital 3 axes accelerometer which cost EURO 14.95 and allow you to measure acceleration with Raspberry Pi

14. Digital 3-axes magnetometer which cost EURO 7.95

15. RS485 convertor with 1000V isolation which cost EURO 16.95 and allow Raspberry Pi to talk to instruments or DMX network

16. Thermocouple module which cost EURO 11.95 which allow Raspberry Pi to measure temperature -200C+700C with 0.25 resolution and as these modules are addressable you can attach as many thermocouples as you need

17. Heartbeat biofeedback sensor which cost EURO 25.95 and allow Raspberry Pi to log EKG signals

18. Pulse oximeter biofeedback module which cost EURO 25.95 and allow Raspberry Pi to log oxigene levels in the blood.

Many new modules are on design stage including: 3-channel RGB LED controller, 3-channel 110/220VAC dimmer controller, Single phase Energy metering module etc etc.

BeagleBone-UEXT adapter is on the way also 🙂

Evaluating low cost USB to Ethernet converters


A13-OLinuXino have no wired Ethernet connection and using WIFI is not always possible so we were looking around for suitable USB to Ethernet converter which to offer.

There are tons of these convertos on ebay starting from as low as $3 including shipment!

The competition between the Chinese factories is enormous, so you can find generally thousands of variations of every product and have to be little cautious as the general Chinese business model is somehow like this: Company A release product on the market and charge let’s say 100 for it, once the product is well accepted and sales are good company B,C and D immediately are seeing business opportunity and copy the product but try to make it at lower cost, usually this comes not from some kind of innovation but just from using lower grade components or removing some components which are for the FCC/CE safety approvals and release product which looks same but sells for 70.
After a while companies E,F,G decide to enter also this market and make new iterration but now the product cost 50 and as you guess right they use even lower grade components.

On first sight all products look same, but when you got them you see that they do not function equally.
Usually there are brands in China which prduce better products and local knows them, so I asked our sourcing agent to take 4 USB to Ethernet adapters which are from brands he trust.

We got them and needless to say they were looking all the same 🙂

Imageso we start our tests:

#1 was not recognized when plugged for a first time, maybe bad USB connector? then after few plugs and unplugs it start working, we copy 60MB tar file and measure 800KB/s transfer which is not bad, opening this dongle and looking at the components it uses AX88772 USB to Ethernet converter which supports 480Mbit mode

#2 was recognized and enumerated correctly from the very first time it works 5 times slower compared to #1 and we achieved only 150KB/s, opening and looking at the components show QF9700 USB to Ethernet converter which supports USB 1.1 only 12Mbit mode (although on the package is written USB 2.0 😉 )

#3 was not recognized at the first time and after a while started working but we didn’t manage to copy file with it, probably lot of packets were lost from time to time this adapter was managing to open web site, but overall it was worst than all we evaluated, inside was QF9700

#4 worked from the first time and achieved 800KB/s same as #1 inside is AX88772 and this definitely is the best perfrming adapter of all 4 so probably this is what we are going to stock and offer as A13-USB-Ethernet adapter

out of couriousity we try LAN9512 which we put on iMX233 and the transfer was similar to AX88772 i.e. about 1MB/s.

Low Cost LCD-TO-VGA adapter


A13 processor have no HDMI and VGA output as his big brother A10, so we had to work out something using the LCD interface it have.

We browsed IC video DACs and there is plenty of them, but they are expensive and didn’t fit well OLinuXino low cost concept, so we decided to give a try and make simple R ladder video DAC.

A13 LCD interface is 18 bit this means we will need 3 channels x 6 bit Video DAC.

All VGA monitors have 75 ohm terminator on their input lines and the video signal is 0.75V for white level and 0V for black. So knowing this we could make resistor ladder DAC with R, 2R, 4R, 8R, 16R, 32R connected in parallel with RGB 0-5 bits. The values are easy to calculate when we know the LCD buffer output voltage 3.3V and the voltage we want to have when all bits are “1” i.e. 0.75V. The resistors using the 1% precission values picked were 549 ohm, 1050 ohm, 2180 ohm, 4370 ohm, 8660 ohm, 17800 ohm.

The adapter was routed and pcb prototypes were run. The assembled adapter was attached to LPC1788 board with 4.3″LCD with tweaking the output to match VGA lock frequency and the result was perfect.


The picture which appears on LCD was color stripes with small ball which you can move by tilting the board (using on-board accelerometer), as you can see from the picture the colors are perfect and image is standing still with no glitches and jitters.

So now we have low cost VGA solution for our A13-OLinuXino and can move forward with the PCB schematic finish and routing. Note that the VGA signals go through buffers which are gated i.e. we can enable and disable the VGA output and A13-OLinuXino will be able to work with both LCDs and VGA.

EDIT: schematic is included here below:

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