@(#)$Id: wmr918.txt,v 1.2 2004/01/14 06:58:03 twitham Exp $

wmr918d dataspec Id: dataspec,v 1.7 2000/12/14 22:28:36 stanley Exp

John Stanley
stanley@peak.org

WMR-918 serial data is transmitted at 9600 baud, 8N1.

Each packet starts with two binary bytes of 0xFF. Each packet ends with a
checksum. The type of packet is given by the third byte, and ranges from
0x00 through 0x0f. Each type of packet has a predetermined length.

For example, a typical type 5 packet looks like:

  ff ff 05 00 09 02 47 09 dc 0c 50 79 0f

The checksum is the simple addition of each byte in the packet, excluding
the checksum byte, keeping only the lowest 8 bits. 

In all further examples, the leading "ff ff" will be omitted. The .tab
output from wmr918d omits the leading "ff ff".

The known packet types are:

	00 - anemometer and wind related data
	01 - rain guage
	02 - extra sensors
	03 - outside temp, humidity and dewpoint
	04 - unknown
	05 - inside temp, humidity, dewpoint, and baro.
	06 - inside temp, humidity, dewpoint, baro for wmr968 and some
		wmr918's.
	07 - unknown
	08 - unknown
	09 - unknown
	0a - unknown
	0b - unknown
	0c - unknown
	0d - unknown
	0e - sequence number
	0f - hourly status report

The following description will attempt to use the same format as the WX200 
listing by Mike Wingstrom. H is a hex digit from 0 to f. D is a decimal digit
from 0 through 9. B is bit encoded, bit 3 is the high bit (0x8).

Type 00

	Example: 00 00 90 01 00 00 00 07 96

Byte	Nibble	Bit	Meaning
00. 0	00		Anemometer data packet
00. 1	Bx		Battery status. Higher value == lower battery volt
00. 1   xB		Unknown
00. 2	DD		Gust direction, bc of 0<abc<359 degrees
00. 3	xD		Gust direction, a  of 0<abc<359 degrees
00. 3	Dx		Gust speed, c  of 0<ab.c<56 m/s
00. 4	DD		Gust speed, ab of 0<ab.c<56 m/s
00. 5	DD		Average speed, bc  of 0<ab.c<56 m/s
00. 6	xD		Average speed, a of 0<ab.c<56 m/s
00. 6	Bx	3	Sign of wind chill, 1 = negative
00. 7	DD		Wind chill

	Example: gust at 190 degrees, 0 m/s, average 0, wind chill 7 Celsius

Type 01

	Example: 01 00 92 62 02 00 00 00 15 21 09 03 00 37

Byte	Nibble	Bit	Meaning
01. 0	01		Rain guage packet
01. 1	Bx		Battery status. Higher value == lower battery volt
01. 1   xB		Unknown
01. 2	DD		Rain rate, bc of 0<abc<999 mm/hr
01. 3	xD		Rain rate, a  of 0<abc<999 mm/hr
01. 3	Dx		Bucket tips since ??
01. 4	DD		Rain Total, cd of 0<abcd<9999 mm (?)
01. 5	DD		Rain Total, ab of 0<abcd<9999 mm (?)
01. 6	DD		Rain Yesterday, cd of 0<abdc<9999 mm (?)
01. 7	DD		Rain Yesterday, ab of 0<abcd<9999 mm (?)
01. 8	DD		Total reset minute
01. 9	DD		Total reset hour
01.10	DD		Total reset day
01.11	DD		Total reset month
01.12	DD		Total reset year 

	Example: 292 mm/hr, 0 yesterday, 2mm total since 21:15 9-Mar-2000
	
Type 02

	Example: 02 81 71 00 87 05 ff

Byte	Nibble	Bit	Meaning
02. 0	02		Outside temp/humidity data
02. 1	Bx		Battery status. Higher value == lower battery volt
02. 1   xB		Unknown
02. 1	xB		Sensor number bit encoded, 4=3 2=2 1=1
02. 2	DD		Outside temp, bc of -?<ab.c<? Celsius
02. 3	xD		Outside temp, a  of -?<ab.c<? Celsius
02. 3	Bx	3	Sign of outside temp, 1 = negative
02. 4	DD		Relative humidity, ab of ?<ab<? percent
02. 5	DD		Dew point, ab of 0<ab<? Celsius

	Example: 7.1 Celsius, 87% humidity, dew point 5 Celsius

Type 03

	Example: 03 01 71 00 87 05 ff

Byte	Nibble	Bit	Meaning
03. 0	03		Outside temp/humidity data
03. 1	Bx	3	Sign of dew point, 1 = negative --twitham
03. 1	Bx	2-0(?)	Battery status. Higher value == lower battery volt
03. 1   xB		Unknown
03. 2	DD		Outside temp, bc of -?<ab.c<? Celsius
03. 3	xD		Outside temp, a  of -?<ab.c<? Celsius
03. 3	Bx	3	Sign of outside temp, 1 = negative
03. 4	DD		Relative humidity, ab of ?<ab<? percent
03. 5	DD		Dew point, ab of 0<ab<? Celsius

	Example: 7.1 Celsius, 87% humidity, dew point 5 Celsius

Type 05

	Example: 05 00 11 02 46 09 dc 0c 50 79 16

Byte	Nibble	Bit	Meaning
05. 0	05		Inside sensor data
05. 1	Bx		Battery status. Higher value == lower battery volt
05. 1   xB		Unknown
05. 2	DD		Inside temp, bc of -?<ab.c<? Celsius
05. 3	xD		Inside temp, a  of -?<ab.c<? Celsius
05. 3	Bx	3	Sign of temp, 1 = negative
05. 4	DD		Relative humidity, ab of ?<ab<? percent
05. 5	DD		Dew point, ab of 0<ab<? Celsius
05. 6	HH		Baro pressure, convert to decimal and add 795. mb.
05. 7	Bx		Unknown
05. 7	xB		Encoded 'tendency' 0x0c=clear 0x06=partly cloudy
			0x02=cloudy 0x03=rain
05. 8	DD		Sea level reference, cd of <abc.d>. 
05. 9	DD		Sea level reference, ab of <abc.d>. Add this to raw
			bp from byte 6 to get sea level pressure.

	Example: 21.1 Celsius, 46% humidity, dew point 9 Celsius
		 BP 1015 mb, sea level pressure 1015 mb.

Type 06

	Example: 06 00 29 02 41 09 8b 61 90 33 06 2e

Byte	Nibble	Bit	Meaning
06. 0	06		Inside sensor data
06. 1	Bx		Battery status. Higher value == lower battery volt
06. 1   xB		Unknown
06. 2	DD		Inside temp, bc of -?<ab.c<? Celsius
06. 3	xD		Inside temp, a  of -?<ab.c<? Celsius
06. 3	Bx	3	Sign of temp, 1 = negative
06. 4	DD		Relative humidity, ab of ?<ab<? percent
06. 5	DD		Dew point, ab of 0<ab<? Celsius
06. 6	HH		Baro pressure, low byte (bc of abc)
06. 7	xB	0 	Baro pressure, a of abc. Convert abc from hex
			to decimal, add 600. to get mb. 
			a is low bit only.
			Upper three bits may be encoded BP tendency.
06. 7	Bx		Encoded 'tendency' 0x0c=clear 0x06=partly cloudy
			0x02=cloudy 0x03=rain
06. 8	DD		Sea level reference, ef of <abcd.ef>. 
06. 9	DD		Sea level reference, cd of <abcd.ef>. 
06.10   DD              Sea level reference, ab of <abcd.ef> Add this to raw
			bp from byte 6 and 7 to get sea level pressure.

	Example: 22.9 Celsius, 41% humidity, dew point 9 Celsius
		 BP 995 mb, sea level pressure 1028.9 mb.

Type E

	Example: 0e 81 8d

Byte	Nibble	Bit	Meaning
0e. 0	0e		Sequence number packet
0e. 1	Bx		Status, high bit, battery for main unit
0e. 1	DD		After removing high bit, minute chime

	Example: status = 1, time is hh:01

Type F

	Example: 0f 80 07 09 03 00 a0

Byte	Nibble	Bit	Meaning
0f. 0	0f		Hour Chime
0f. 1	BB		Status. High bit == battery low
0f. 2	DD		Hour 
0f. 3	DD		Day 
0f. 4	DD		Month 
0f. 5	DD		Year 

	Example: It's 7AM, 9-March-2000, do you know where your weather
		station is?


Thanks to the following people for providing additional data and pointing
out my stupid mistakes:

John R. Covert
Brad and Stephanie Grant
Giovanni BOGLIONE
Alan K. Jackson
Roy (garlic)
Krenn Werner
Steven Danz
Barry Newton

$Log: wmr918.txt,v $
Revision 1.2  2004/01/14 06:58:03  twitham
Maybe fixed negative outdoor dewpoint and its low.

Revision 1.1  2001/09/08 21:40:10  twitham
Merged in initial WMR918 support by Dominique Le Foll.

Revision 1.7  2000/12/14 22:28:36  stanley
changed byte 7 of type 6

Revision 1.6  2000/12/06 06:12:24  stanley
added type 6, corrected some typos, added battery status

Revision 1.5  2000/09/04 23:02:28  stanley
fix month/day mixup in type f

Revision 1.4  2000/07/31 03:16:07  stanley
type 5 sealevel ref fixed, trend decoded, avgwind fixed

Revision 1.3  2000/04/10 14:47:35  stanley
fixed meaning of type E -- minute chime!

Revision 1.2  2000/04/07 16:49:29  stanley
fix typos

Revision 1.1  2000/04/07 05:53:27  stanley
Initial revision