On Tuesday 20 February 2007 00:52, Ankur Kamthe wrote:
> I was attempting to establish communication between a tmote and a
> slave i2c device (cyclops camera). The led on the slave device is
> supposed to blink everytime I press the user button on the mote.
>
> I am assigning the slave device the address 0x80 (=value and bcast =
> true). While writing packets to the I2C bus the mote calls the slave
> device using address 0x80. I, also tried calling the slave device
> using 0x00 since bcast is enabled, however I was unable to get any
> response from the slave device (no leds blink)
>
> Could someone be able to tell me if I am atleast assigning the correct
> addresses to these entities?

A common confusion is that some docs I've seen list the address value as an 
8-bit value, including the lsb which is a read/write flag, while other docs 
list it as a 7-bit value that is followed on-the-wire by the read/write bit.  
I wonder if 0x80 is really an addr of 0x40...

Also, I think TMotes have a pull-up onboard for only one of the two I2C signal 
lines...

Steve

>
> thanks,
> ankur
>
> for reference:
>
>    /*
>      * Sets the address of the I2C Slave
>      *
>      * @param value The 7 lower bits of value are the I2C slave address.
>      * @param bcast determines whether slave will respond to general call
>      *  address
>      *
>      * @return SUCCESS always
>      */
>     command result_t setAddress(uint8_t value, bool bcast);
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