dccch
- 21st January 2008, 22:27
Dear all,
I'm building a temperature logger for my solar panels.
The program is running fine as long as the 1-wire Dallas sensor is connected using a reasonably short cable, e.g. 3-4m. When I try using a 20m cable then the LCD display just hangs and no temperature measure takes place. The cable is a regular power cable with 3 wires (no twisted pairs)
I've changed the far end pullup resistor (i.e. close to the DS1820) from 4K7 down to 2K2 and this seems to allow me to use longer cables (10-12m) but it still doesn't work at 20m.
The Dallas 1-wire design guide is mentionning a 100-150m radius value, so I'm confused.
My design is based around a 16F628 @8Mhz.
Anyone with similar "long cable" design experience ?
Best rgds
I'm building a temperature logger for my solar panels.
The program is running fine as long as the 1-wire Dallas sensor is connected using a reasonably short cable, e.g. 3-4m. When I try using a 20m cable then the LCD display just hangs and no temperature measure takes place. The cable is a regular power cable with 3 wires (no twisted pairs)
I've changed the far end pullup resistor (i.e. close to the DS1820) from 4K7 down to 2K2 and this seems to allow me to use longer cables (10-12m) but it still doesn't work at 20m.
The Dallas 1-wire design guide is mentionning a 100-150m radius value, so I'm confused.
My design is based around a 16F628 @8Mhz.
Anyone with similar "long cable" design experience ?
Best rgds