1 Wire pull up resistor
27 March, 2012 - 15:19
Can someone clear something up for me with regards the pull up resistors on the temp sensors.
Do I need to use 1 pull up resistor per sensor IC, or is it just 1 pull up resistor for the whole array?
28 March, 2012 - 08:18
#3
Exact values and location
depend on cabling type, length and quality. Main target here like I was teached by Derek is to have pullup resistors close to sensors.
E.g. one of the configurations working for me:
- six sensors, cat5 cabling, total length around 100m
- connections are star-like, each sensor on a separate leg
- resistors soldered to sensors are 2k7, 2k4, 6k8, 6k8, 2k7, 1k6 (smaller values for longer legs)
- total resistance is around 480 ohms that is close to limit (maybe over already in some other setup)
BR,
Aivo
28 March, 2012 - 11:12
#5
It about total resistance
Lawrence. It's not about number of resistors it's about total resistance and bus type. For an unusual and star shape bus individual resistors at each sensor seems to work best for a simple bus 1 resistor will be fine It's a case of trial and error I find! Thanks Garry
That's an easy one. One pull up resistor per 1-wire bus. As only 1 bus is provided you need but 1 resistor.
Its value well there is another discussion right there. It can move around depending on the length and number of devices on your bus.