For the LED Matrix we want to build on the CCCamp2007 we decided to design a GNU LEDMatrix Controller/Driver setup. It will consist of two parts the FPGA board and a several driver electronics boards. Now almost one year later we're still working on it :)
Everything is soldered and it works. We still need to figure out a fast way to get Video data to the matrix.
72x48 pixels totals 3456 blue leds 54 column driver modules (current source). 1 row driver mudule (current sink)
The 8 rows are each connected to a powermosfet and are driven to ground one at a time (so the matrix is 8times multiplexed). For driving the mosfets we use two Quad-mosfetdriver which in turn are controlled by a 8bit shifting register.
For the columns we take almost the same components except that we have to source current. The mosfets can source up to 250mA but we limit it to about 20mA.
New MiniITX Board
- http://www.i2c-bus.org/ very good read on i2c specs
- https://help.ubuntu.com/community/ViaEpiaDriHowto kernel stuff for i2c
- http://robots.net/article/983.html article on this board
- http://www.nxp.com/#/pip/pip=[pfp=41735]|pp=[v=d,t=pfp,i=41735,fi=,ps=0] i2c specs
- http://codesink.org/eeprog.html sample userland app using i2c on the via board
- http://www.linuxjournal.com/article/7136 i2c kernel driver linux stuff
There are three data transfer speeds for the I2C bus: standard, fast-mode, and high-speed mode. Standard is 100 Kbps. Fast-mode is 400 Kbps, and high-speed mode supports speeds up to 3.4 Mbps. All are backward compatible. The I2C bus supports 7-bit and 10-bit address space devices and devices that operate under different voltages.
100kHz and 400kHz are *maximum* frequency for standard and high-speed
- I2C* busses. What your VIA bridge really is is an SMBus, so it must run
at a speed between 10kHz and 100kHz if I remember correctly.
As a matter of fact, I already measured both my VIA and Intel SMBus chips at 16kHz, exactly like you. So I am not surprised at all by what you are reporting.
kernel patch UNTESTED: http://archives.andrew.net.au/lm-sensors/msg29186.html