Add R900 BCD Protocol (#58)

* Implement R900 BCD parser.
* Register r900bcd protocol in main program.
* Add r900bcd to msgtype flag description and readme.
* Correct samplefile default value in documentation.

Author: bemasher

README.md

@@ -31,7 +31,7 @@ Usage of rtlamr:
   -format=plain: format to write log messages in: plain, csv, json, xml or gob
   -gobunsafe=false: allow gob output to stdout
   -logfile=/dev/stdout: log statement dump file
-  -msgtype=scm: message type to receive: scm, idm, r900 or scm+
+  -msgtype=scm: message type to receive: scm, scm+, idm, r900 and r900bcd
   -quiet=false: suppress printing state information at startup
   -samplefile=/dev/null: raw signal dump file
   -single=false: one shot execution, if used with -filterid, will wait for exactly one packet from each meter id
@@ -53,7 +53,6 @@ rtltcp specific:
   -tunergain=0: set tuner gain in dB
   -tunergainmode=false: enable/disable tuner gain
   -tunerxtalfreq=0: set tuner xtal frequency
-
 ```
 
 Running the receiver is as simple as starting an `rtl_tcp` instance and then starting the receiver:

flags.go

@@ -38,7 +38,7 @@ var logFile *os.File
 var sampleFilename = flag.String("samplefile", os.DevNull, "raw signal dump file")
 var sampleFile *os.File
 
-var msgType = flag.String("msgtype", "scm", "message type to receive: scm, idm, r900 or scm+")
+var msgType = flag.String("msgtype", "scm", "message type to receive: scm, scm+, idm, r900 and r900bcd")
 
 var symbolLength = flag.Int("symbollength", 72, "symbol length in samples")
 

main.go

@@ -34,6 +34,7 @@ import (
 
 	_ "github.com/bemasher/rtlamr/idm"
 	_ "github.com/bemasher/rtlamr/r900"
+	_ "github.com/bemasher/rtlamr/r900bcd"
 	_ "github.com/bemasher/rtlamr/scm"
 	_ "github.com/bemasher/rtlamr/scmplus"
 )

r900bcd/r900bcd.go

@@ -0,0 +1,49 @@
+// RTLAMR - An rtl-sdr receiver for smart meters operating in the 900MHz ISM band.
+// Copyright (C) 2014 Douglas Hall
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published
+// by the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package r900bcd
+
+import (
+	"strconv"
+
+	"github.com/bemasher/rtlamr/parse"
+	"github.com/bemasher/rtlamr/r900"
+)
+
+func init() {
+	parse.Register("r900bcd", NewParser)
+}
+
+type Parser struct {
+	parse.Parser
+}
+
+func NewParser(symbolLength, decimation int) parse.Parser {
+	return Parser{r900.NewParser(symbolLength, decimation)}
+}
+
+// Parse messages using r900 parser and convert consumption from BCD to int.
+func (p Parser) Parse(indices []int) (msgs []parse.Message) {
+	msgs = p.Parser.Parse(indices)
+	for idx, msg := range msgs {
+		r900msg := msg.(r900.R900)
+		hex := strconv.FormatUint(uint64(r900msg.Consumption), 16)
+		consumption, _ := strconv.ParseUint(hex, 10, 32)
+		r900msg.Consumption = uint32(consumption)
+		msgs[idx] = r900msg
+	}
+	return
+}