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Hello
Do you have sourccode to interpretate the transmission from the "rooms" sketch/program on the pc side? I don't want to "reinvent the wheel" from the struct in rooms and to read lots of data-sheets for the DS18B20 etc. etc., convert bits and bytes to human text if you have already done that ones. I'm to lacy for that.(-;
WR/ B Mathias Johansson
Hi bmj,
To get the data from the rooms nodes on a (usb) serial port on your PC, you can use a little sketch (on a jeelink for instance) that JCW uses for JeeMon, you can find it here:
http://talk.jeelabs.net/topic/29
This will print a "HM4 <hexbytes...>" string upon a valid reception of rooms message.
The <hexbytes> correspond to the payload struct from the rooms sketch. Note that because of the bitfields in the payload struct, you will actually receive 4 octets of data in <hexbytes>.
Divide the temp field by ten to get the temperature in Celsius.
You don't need to read data sheets. These are the bytes sent, as you can see in the rooms.pde sketch:
struct {
byte light; // light sensor
byte moved :1; // motion detector
byte humi :7; // humidity
int temp :10; // temperature
byte lobat :1; // supply voltage dropped under 3.1V
} payload;
I don't use C code to decode this, so can't help with that, sorry. Basically a bunch of shifts and byte combines should do it.
Thanx to both of you!
I did as Andras suggested and looked in the JeeMon code and found the following code to interpret the struct to "human form". All I have to do now is to code the same in C or Python. I was worried that the bits in the struct for the temperature where harder to process. I will put the code her for others to use when it is tested.
----Snipp from JeeMon--->
# decode readings from nodes running the rooms sketch
178 proc ROOM {date id a b c d} {
179 set secs [Secs $date]
180 dataset newReading light$id $secs $a
181 dataset newReading moved$id $secs [expr {$b & 1}]
182 dataset newReading humid$id $secs [expr {$b >> 1}]
183 set temp + $c) ^ 512) - 512}]
184 dataset newReading temp$id $secs $temp
185 }
----