CisternMongoose web-ui

Since the TP-Link has some unused GPIOs, the SRF05 could be connected directly to the TP-Link by using a single line for triggering/data acquisition. The values from the sensor are exported to sysfs by the kernel module. Then, the web-service reads out the data from there and provides them as JSON. Also the web service provides a simple static HTML page using microAjex to retrive and display the JSON. The web service is written in plain C and uses the excellent mongoose as a foundation. Thus, the whole thing is only about 110k small. To create a long-term statistic, the measured data is written to a CSV file every hour.

MR3020 with Kyle supervising and SRF05 connected

MR3020 cracked open, wires for 3.3V, GND and data connected

(Unfinished) mounting of MR3020

Cistern cover, sensor (with enclosure) below

PartSim includes a full SPICE simulation engine, web-based schematic capture tool, and a graphical waveform viewer.

PartSim

Beside providing a simple API to manage messages and variables, a wrapper framework is provided. The wrapper framework helps with implementing sensor clients that run in the background as daemons.

Currently there is a fully featured wrapper included for wrapping the GPIOs of an Raspberry Pi into an Scratch remote sensor client. This allows one to access the GPIOs of the Pi from Scratch by simply setting/getting some global variables.  The videos below show how the Pi wrapper is used from Scratch. For more details see the project page.

Raspberry Pi GPIOs as Remote Sensors Part 1

Raspberry Pi GPIOs as Remote Sensors Part 2

For more details see the following shell-script:

pyscmpd is a music player daemon I use to convert my Raspberry Pi into a “soundberry”. The daemon is talking a subset of the MPD protocol, but instead of serving local MP3 files, it connects to soundcloud.com and serves the streams found there. Because of the MPD protocol, a huge number of clients could be used as a front end to the daemon (e.g. ncmpcpp, sonata). It is user configurable, which parts of soundcloud.com are made available for browsing (by defining categories and adding groups or users to them).

• Get the release TAR-ball from github
• Got to the project page

• For more details, see the project page here
• Get the sources from github

The (unedited) video below shows some examples of how the board could be used with Scratch:

The Carambola comes with 2mm pin connectors, I used a 2mm perf board to host the Carambola, and then piggybacked the MSP430 on a 2,54mm stripe board. The MSP430 communicates with the Carambola through UART1 with the help of uSherpa-Firmware and the uSherpa-Python-Client-API.

Since the Carambola on the Robot is powered from a 7.4V LiPo battery, two DC step-down converters from Pololu are used: one for 5V which goes to USB, and one for 3.3V which powers the logic of the Carambola as well as of the MSP430. The Carambola seams kind of picky regarding the 3.3V supply. I was not able reliably powering the Carambola by using standard LM7805/TS2940 regulators. The step-down converters are mounted in diagonal to the perf board, since the have a 2,54mm pin-out, and by placing them like so, I barely was able to solder them to some of the whole of the 2mm perf board.

An other thing a noticed about the Pololu Step-Down Voltage Regulator D24V6ALV was, that they do not come up reliably when SHDN pin is left open. The manual says, it could be left open, or connected to VIN to enable the board. Well leafing it open was no success, connecting it to VIN works well.

Carambola and MSP

Carambola with MSP piggyback

The following table shows, how pins of the Carambola are connected:

Carambola Stand Alone (with USB)

Some notes about power consumption:

• You need to supply at least 300mA, otherwise the Carambola is starving.

Some notes about the USB connection:

• For using USB, 5V has to be provided to pin 21 (when not using USB, there is no need to provide 5V).
• UPHY (pin 40) needs to be grounded to tell the USB controller to run in master mode.
• No ESD protection when connecting as described! Thus, I recommend not to hot-plug devices when using this unprotected approach!