[Weather] New Barometer Chip

[Mark Richards]

Matthew Smith wrote:
 >
 > This sort of device looks good to me, as I am planning to move away
 > from pure 1-Wire to "smart" sensors on a more robust bus - automotive
 > fault-tolerant CAN.

CAN is only good out to 40 meters or so, is that correct?  If this is 
the practical limit 1-wire has it beat on that score.

We're running into some situations as we continue to beta test our 
system where the limitations of 1-wire are being seen, both as a result 
of total length of cable and number of devices on it.  Some "smart 
sensor" ideas are being looked at which might bring remote i2c into the 
picture with 1-wire repeaters where needed.

> Just to elaborate on my plans so far, devices require a four-conductor
> cable (CAN+, CAN-, GND, B+), with each node comprising uC, CAN
> transceiver, RTC, serial to 1-Wire, I2C and/or SPI, voltage regulator,
> surge protection, provision of some form of backup power (supercap,
> NiCD, something).  Possibly some external RAM to allow for continuous
> monitoring during prolonged outages of the host controller (like when
> the PC blows up).
... unless it's 40 meters between transceivers, max.

/m