Re: Find something in the street and plug it in.

[tom r lopes <tomrlopes@gmail.com>]

Pics https://photos.app.goo.gl/ygRRafkWeNp6r8dh6

On Sat, Oct 5, 2019 at 11:23 AM tom r lopes <tomrlopes@gmail.com> wrote:

Not quite plug it in but a day or so ago I found a little device on the sidewalk.  A 2x2x3/4 in plastic 

box with an LED and text: REMOTE SENSOR 433 MHz Wireless.  Um, I thought, wonder if you could decode this with an SDR dongle.  

Turns out some one has already done it.  Yay open source!  RTL_433 on Github https://github.com/merbanan/rtl_433 

rtl_433 is in Debian testing and Ubuntu 19.10.  

I installed from github as I run 18.04.  

tom@tom-desktop:~$ rtl_433 -C customary

time      : 2019-10-05 02:51:30
model     : Prologue sensor                        id        : 9
rid       : 222          Channel   : 3             Battery   : LOW
Temperature: 66.38 F     Button    : 0
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
time      : 2019-10-05 02:51:30
model     : Springfield Temperature & Moisture     SID       : 157
Channel   : 3            Battery   : LOW           Transmit  : MANUAL
Temperature: 126.1 F     Moisture  : 15            Integrity : CHECKSUM
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
time      : 2019-10-05 02:52:26
model     : Prologue sensor                        id        : 9
rid       : 222          Channel   : 3             Battery   : LOW
Temperature: 66.56 F     Button    : 0
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
time      : 2019-10-05 02:53:22
model     : Prologue sensor                        id        : 9
rid       : 222          Channel   : 3             Battery   : LOW
Temperature: 66.56 F     Button    : 0
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Mine is the Prologue sensor.  After running a couple hours it found another sensor.  I was running the SDR stick without an antenna so maybe it could pick up more.  

You can see an explanation of the protocol in the source: https://github.com/merbanan/rtl_433/blob/master/src/devices/prologue.c

Prologue sensor protocol,
	also FreeTec NC-7104 sensor for FreeTec Weatherstation NC-7102,
	and Pearl NC-7159-675.
	The sensor sends 36 bits 7 times, before the first packet there is a sync pulse.
	The packets are ppm modulated (distance coding) with a pulse of ~500 us
	followed by a short gap of ~2000 us for a 0 bit or a long ~4000 us gap for a
	1 bit, the sync gap is ~9000 us.
	The data is grouped in 9 nibbles
	[type] [id0] [id1] [flags] [temp0] [temp1] [temp2] [humi0] [humi1]
	- type: 4 bit fixed 1001 (9) or 0110 (5)
	- id: 8 bit a random id that is generated when the sensor starts, could include battery status
	the same batteries often generate the same id
	- flags(3): is 0 the battery status, 1 ok, 0 low, first reading always say low
	- flags(2): is 1 when the sensor sends a reading when pressing the button on the sensor
	- flags(1,0): the channel number that can be set by the sensor (1, 2, 3, X)
	- temp: 12 bit signed scaled by 10
	- humi: 8 bit always 11001100 (0xCC) if no humidity sensor is available

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