When looking for documentation on Ethernet, one can easily find that the frame includes a Frame Check Sequence. This is a bunch of bits that allow the receiver to verify the frame. If the frame somehow got corrupted on its way from sender to receiver, the FCS will not match the frame data and the receiver will discard the corrupt frame. Exactly how this FCS is calculated is not that easy to find.
Posts tagged ‘electronics’
Our weather station has a serial connection and comes with Windows-software to view the weather data on your PC. The app is very eye-candy, but doesn’t do anything more than displaying the data. I’m more interested in long-term trending. So I wrote my own application to talk to the weather station and store the result in an rrdtool database.
Continue reading ‘Reverse engineering the Oregon WMR928NX weather station’ »
A few months ago, I got the FlyCamOne2 as an add-on for my Raptor. The manual mentions that the recording can be started and stopped electronically. With some additional electronics, it should be possible to start/stop the camera from the ground using one of the free channels on my remote.
The free channel can’t be used directly: the receiver sends out pulses of different lengths (between 1ms and 2ms), while the FlyCamOne2 needs a simple short to start recording. Some electronics will be needed to convert between these two.
After some googling, I found the CurveRC FCO2 I/F which does exactly that. But there are some downsides:
- It consumes a lot of power (10mA on 5V)
- Isn’t cheap (£10, plus international shipping, at the time of this post)
- I don’t get to enjoy myself figuring out how to do this myself
The CurveRC print seems to be build around an Atmel Tiny25 microcontroller, which is an 8bit RISC processor with 2K of build-in flash. Using a microprocessor makes the design fairly simple since nearly everything can be done in software. However, it must be clocked at reasonable speed to do something useful. This explains the fairly high power consumption.
So I decided I could do “better”.
