New eye

We started the day by understanding the LIN protocol. We will use it to communicate between the robot and the extarnal module. I firstly chose just a mono jack with 2 wires. Samuel and Alexis told us that it would be easier to split the data and the power supply. As a consequence, we have changed for stereo jack with 3 wires. The unit in the external module is a ATtiny87.

Another surprise, Samuel try the WiFi chip. Bad news, the driver is not finished. We can’t use the SPI for transferring data, we have to use the serial port for controlling order and transferring data.
Goodbye the 10M/s, we have to analyze the camera again.

Firstly, we have chosen a GumStix Caspa VL. However, the resolution is 752×480 and each pixel contains 10 bits.
752*480*10 =3,609,600 bits for just one image !! Moreover flo sent a mail on the GumStix mailing list, he asked how we can manage the problem with the STM32F4 processor. In five minutes, he got the answer: that it’s too difficult! Let’s find an other camera.

Welcome to the new camera: OV2640. On top of that, the OV2640 camera supports JPEG. Thus, we will have lighter picture 🙂
A project using a OV2640 with a STM32F4 : openMV


[StabiloRose] Concerns about WiFi

After my little post of yesterday, I tried to figure out if I was right, if the LED strips really blocks WiFi waves. I used old LED strips from a previous ROSE project and surround my phone with them. After many tries, the phone was still connected to the school network.

I see a few explanations:

1. I was wrong, the strips are not blocking WiFi waves. Everything is perfect, we don’t have to use an external antenna. But I don’t think that’s correct.

2. My phone is a Moto G 4G. I tried to find the position of its WiFi antenna, but found nothing interesting. It may be located in a corner, and the strips haven’t had a big influence on it.

3. Android is trapping me, saying he is always connected whereas it is not. He might say he is disconnected only after a certain number of reconnection failures.

Anyway, nothing can be really sure about our sphere at this time. Fortunately, the WiFi module can be connected to two external antennas. And we can switch between them. This gives us the liberty to put an internal antenna and a connector.