pmeerw's blog

Apr 2012

Fri, 13 Apr 2012

SCCB is not I2C

When reading the descriptions of the I2C protocoll or some other two-wire interface that behaves like I2C in a random datasheet, one often has the impression to have discovered a totally new protocoll. The same thing is described differently, every time!

However, SCCB (serial camera control bus), Omnivision's I2C variant is different: the ACK bit (the 9th bit after each byte of data transmission) does not indicate ACK or NAK but is set at random -- the I2C master is supposed to ignore it.

posted at: 10:50 | path: /projects | permanent link

Wed, 04 Apr 2012

Soldering fun: put TCA6507 I2C LED driver on a SSOP-20 breakout

I tried to hook up some LEDs on the beagleboard-xm using an I2C LED driver (TCA6507 datasheet). Difficult part was to put the SSOP-20 chip on a breakout board (SSOP-to-DIP adapter, from sparkfun).

The TCA6507 can cope with the 1.8 V from beagleboard's expansion header and the 5 V power supply.

There is a Linux driver for the TCA6507 (since 3.3), so you can control the LEDs nicely: i2cset -f -y 2 0x45 0x02 0xff to turn on all LEDS to full brightness.

posted at: 13:38 | path: / | permanent link

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