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21 Jul 2011

Build a ‘Klout Klock’, track your influence and time… [via]

Klout exposes a web service enabling developers to build mash-up applications around its metrics and all that is required to play is an API key which is easily obtained when registering an application. My application is the “Klout Klock” device and before getting into the details of building it, you can see it how it works in this video…

The clock is built using a Netduino Plus and an AdaFruit ST7735 TFT screen. I have described how to connect them together in a previous post here. In that post, I had indicated that managing such a TFT screen from a Netduino was sub-optimal due to the memory requirements involved. That statement is even more true with a Netduino Plus which has roughly 28KB of RAM available for an application. This means that allocating a 40KB buffer to manage the TFT display as I was doing it previously is out of the question.

Build a ‘Klout Klock’, track your influence and time - [Link]

31 May 2011

Fabien wrote a great tutorial on using the Adafruit TFT display with a Netduino. He writes: [via]

AdaFruit recently released a sweet little TFT display that I was dying to hook up to a netduino: the display features a resolution of 128*160 pixels, is capable of showing 18-bit colors and has a microSD card reader on the back of the breakout board. As usual, Limor wrote a nicely detailed Arduino tutorial showing how to connect the display and how to write sketches to drive it.

The Arduino driver relies on the ability of the Atmega168/368 to toggle digital lines extremely fast, which does not work well on the netduino due to the latency introduced by the .Net Micro Framework: even when configured to use hardware SPI, the Arduino driver constantly toggles a data/command output line, rspin below, which would be unbearably slow on the netduino if the same method were applied.

The netduino has one advantage over the Arduino: it has plenty of RAM. So, instead of toggling I/O lines slowly all the time and using next to zero RAM, the netduino driver allocates a 40K buffer corresponding to the resolution of the display in 12-bit depth colors (16 bits per pixel) and leaves the ST7735 in ‘data’ mode upon initialization.

Drawing always happens on the internal buffer first. Then, whenever the actual display needs refreshing, the display I/O operations are performed using hardware SPI, blasting the entire 40K buffer. It may sound crazy but using this method on the netduino is faster than refreshing a single pixel while toggling an I/O line!

Driving an Adafruit TFT Display with a Netduino – [Link]





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