1-Wire device limits (CRC errors when adding more sensors) - Raspberry Pi Forums
hi,
i'm using several rasperries different versions. 1 of them observing (and suppose control) heating system. raspberry pi b model (2014) , still running 3.12.28+ (raspbian 7.6).
on system have 1-wire star bus 18820 temperature sensors (running 9 sensors on 4 segments) .
sensors connected 3-wire cables qith long distance setup rasperry: 5v vdd(pin2) , gpio4(pin7) dd , gnd (pin6) plus 4k7 resistor pulled resistor between 3.3v , dd (one time between pin1 , pin7).
2 of sensors on 10 - 15 m cable, rest 2 sensors each on 2 - 3 m cables.
worked fine 8 sensors, adding 9th challenge environment selective on 9th sensor.
moment add 9th sensor (adding extension existing cable), see crc error messages in syslog sensors (randomly) or existing devices not detected anymore. tried different sensors individuals until found set of 9 working together.
adding 10th again have these troubles....
have 20 sensors, , have added line /etc/modules (that rasperry pi not yet on deive tree) prepared. on same raspberry have (on gpio port set) mcp3008 8 channel ad convertor running, attached i2c.
q1: having multiple 18820 sensors on such environment somehow limited protocol?
q2: cableing critical? connect each cable line sensors using 3.5mm audio head plugs switchbox (which disconnected pi if cable switched). , have soldered sensors on each cable.
q3: right value of pullup resistor more devices? use 4k7 ohm in moment theoretically need adapted more devices?
q4: moving rpi bv2 (2015) , latest raspbian option make more devices working?
q5: make sense set 1-wire bus using different gpio port on same machine? can load 1-wire driver different arguments (to specifying gpio port other dafault 4)?
i'm using several rasperries different versions. 1 of them observing (and suppose control) heating system. raspberry pi b model (2014) , still running 3.12.28+ (raspbian 7.6).
on system have 1-wire star bus 18820 temperature sensors (running 9 sensors on 4 segments) .
sensors connected 3-wire cables qith long distance setup rasperry: 5v vdd(pin2) , gpio4(pin7) dd , gnd (pin6) plus 4k7 resistor pulled resistor between 3.3v , dd (one time between pin1 , pin7).
2 of sensors on 10 - 15 m cable, rest 2 sensors each on 2 - 3 m cables.
worked fine 8 sensors, adding 9th challenge environment selective on 9th sensor.
moment add 9th sensor (adding extension existing cable), see crc error messages in syslog sensors (randomly) or existing devices not detected anymore. tried different sensors individuals until found set of 9 working together.
adding 10th again have these troubles....
have 20 sensors, , have added line
code: select all
wire max_slave_count=20q1: having multiple 18820 sensors on such environment somehow limited protocol?
q2: cableing critical? connect each cable line sensors using 3.5mm audio head plugs switchbox (which disconnected pi if cable switched). , have soldered sensors on each cable.
q3: right value of pullup resistor more devices? use 4k7 ohm in moment theoretically need adapted more devices?
q4: moving rpi bv2 (2015) , latest raspbian option make more devices working?
q5: make sense set 1-wire bus using different gpio port on same machine? can load 1-wire driver different arguments (to specifying gpio port other dafault 4)?
q1, not in theory, in practice different scenario.
q2, see q1
q3, try resistor on each arm of star. can vary wildly in value, between 1k , 10k.
q4, not, running similar issues long before pi's day on arduino.
q5, don't know.
q2, see q1
q3, try resistor on each arm of star. can vary wildly in value, between 1k , 10k.
q4, not, running similar issues long before pi's day on arduino.
q5, don't know.
raspberrypi
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