Hello, I wonder if someone with I2C expertise has these answers, i have similar needs and dont have any more pins available. Regards Alexander
--- In [email protected], Thomas Treyer <[EMAIL PROTECTED]> wrote: > > Hi there, > > I want to connect a Real Time Clock DS1302 and several other I2C > devices to the foxboard. I would like to use the dedicated I2C Pins > for both purposes. > The DS1302 is not a fully compliant I2C-device, but uses a RST pin > for addressing. My first guess is, that both the DS1302 and normal > I2C devices can operate on the same I2C bus. From the reading of data > sheets it seems to be, that the communication between foxboard and > Ds1302 requires no start condition. Therefore I hope, that the > communication between kernel and DS1302 will not wake up all the > other I2C devices. > On the other hand, during the communication of my user program with > the normal I2C devices (e.g. PCF8591) the RST line is not active, and > therefore the DS1302 should sleep peacefully during this time. > > Can anybody confirm, that DS1302 and normal I2C devices can operate > on the same bus? Or is it preferable to use different pins? > > Another aspect can be a race condition, where the kernel tries to > access the I2C bus the same time my user program communicates with > another device at the bus. Is this a real risk or is this avoided by > any method in the I2C driver? > > Does the kernel use the I2C driver for the DS1302 communication or > has the kernel an independent driver for the RTC? > > What happens if my user space program opens /dev/i2c and keeps it > open indefinitely? Will this be a blocking point for the kernel to > access the RTC? > > Please excuse all these silly questions, but these topics are > completely new for me. > > > .................... > Thomas Treyer > > [Non-text portions of this message have been removed] >
