Since a couple of day at work I had to investigate on some network issues for an application, it seems that we have a strange ARP configuration that may be the main issue… by the way, I discovered another strange thing where icmp packets sent in burst mode (like a flood) are lost at variable rates. Here is the note on my investigations
For one of my projects, I want to have a really low power consumption device to be able to use a battery for many month. For this I implemented a low power solution as described here. I’ll try to simplify it a little bit and document it a little more …
RFduino connected to HC-05 bluetooth
I was looking for a system able to work with an iPhone (Bluetooth Low Emission – LBE) and a standard android (Standard bluetooth / rfcom). The RFDuino Arduino platform I have is perfect for BLE so, I decided to add a HC-05 module for the standard bluetooth.
Here is the description on how to make it !
Really interesting tweet I just saw about the Odroid-U3 platform you can find following this link. This platform with the size of a Raspberry PI board is a 4 ARM core 1.7Gb (cortex A9) with 2GB included. Video is HDMI 1080p.Storage is MicroSD slot. The price is really low : 58$
You can ran even Android & Linux on it.
Compared to a RPI, this sound good for video/media box applications, better than RPI. For hacking this is largely different, as you can see on the picture, GPIO connector are not so easy to access. But, you can also purchase an extension shield providing all what you are expected with 36 GPIO. To build your own shield it could be more complicated than RPI. This let me go to a question I have since months … Why RPI is not becoming less and less expensive or more & more powerful ? it have now about 2 year old.
Less negative point : like any new board coming after Raspberry, the ecosystem is actually really smaller and all third party components (box, shields) is really limited.
Now, that said … I have to order one !
ODROID-U3
The RfDuino arduino device i’m actually hacking is a bluetooth 4 (BLE) device. I was expecting to work with it as any bluetooth devices in a terminal session like with rfcomm in previous version of bluetooth.
In fact not ! BLE are not pairable as the classical BT device, they are discovered by the application itself. Then you have communication channel you can read or write to communicate.
Thanks to a post in a forum, I’ve found a really usefull tool lightblue allowing to connect any BLE device and send it data. This soft works on iOS and MacOsX.
You can also get Apple tool : Bluetooth explorer and Packet Logger here.
With the 16×16 123RGB panel base on WS2812b, I have 256leds able to consume up to 50mA each. I want to use this with a limited current under 3A and want to ensure using software, this limit will not be reached. This article detailed my code for doing this.
Each led value is stored in a int array where each value is containing rvb values.
As described in a previous article, I’m investigating ws2812b leds provided with RGB123 board. These leds are providing a lot of light, which is a good thing but also require large power supply to light them on. As in my system, I want to control power to not overload the battery, I’m tring to predict current need and limit it.
In fact, the final equation is really easy to get. According to my different measures, the current is really linear for each of the color, equal for each of them too.
As a consequence, the final current estimate is :
I(mA) = 1 + R/16 + G/16 + B/16