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TFA-Dostmann 30.3015 "Klima Logger"

28-10-2009 version 0.1

Overview

The TFA-Dostmann "Klima Logger" is a thermo-hygrometer with integrated data logger. Additionally to the internal sensors it can also collect the data of up to 5 external (433MHz based) sensors, thus allowing to log the data of up to 6+6 environmental measurements.

Communication Protocol

Communication with the device is accomplished by directly accessing the I2C-attached EEPROM via the internal multi-master I2C bus. The I2C bus is exposed via a simple RS232 interface.

Data Cable Pinout

I2C Signal RJ pin   DB9 pin RS232 Signal at DTE
GND 1 black   5 G
-- 2 yellow < 3 TxD
nSCL 3 blue < 4 DTR
nSDA 4 brown < 7 RTS
SCL 5 green > 6 DSR
SDA 6 white > 8 CTS

N.B.: Only the TxD signal, but not the RxD signal is connected, since communication is carried out via the handshake lines. The TxD signal is only used for requesting access to the I2C bus.

The Protocol

Communication Setup

Set DTR and RTS low (thus set SCL and SDA high).

Write 'U' (0x55) to TxD at 300N1, until the DSR line starts making a ~12%-high duty cycle. A 50% duty cycle means the device is busy with RF reception, which might not be a good time to take over the I2C bus.

Set DTR and RTS high (SCL = 0, SDA = 0) in order to keep control over the i2c bus.

Low-Level Bitbanging

To write one byte over i2c:

for each bit (msb first):

SDA = bit
SCL = 1
SCL = 0

finish up with stop bit:

SDA = 1
status = SDA
SCL = 1
SCL = 0

EEPROM Memory Map

The Klima-Logger features an Atmel AT24C256 EEPROM which provides a 32KiB storage for the measurements.

Parameter Section

0000000 30 14 61 02 91 00 00 ff 01 44 09 00 01 ff ff
        MM HH dW md ym ?y TZ ?? LI LogCt FL SC ?? ??
Addr. Section Bit Format
7 6 5 4 3 2 1 0
00h Timestamp MN2 MN1 BCD/BCD
01h HR2 HR1 BCD/BCD
02h DM1 DW BCD/BCD
03h MO1 DM2 BCD/BCD
04h YR1 MO2 BCD/BCD
05h ? YR2 -/BCD
06h Timezone TZ INT8
07h unknown ?  
08h Log Interval ? LI -/UINT4
09h Log Count LC2 LC1 BCD/BCD
0Ah LC4 LC3 BCD/BCD
0Bh Flags ? OVF ?  
0Ch Sensor Count ? SC -/UINT4
0Dh unknown ?  
0Eh unknown ?  

Timestamp

/   20<YR2><YR1>-<MO2><MO1>-<DM2><DM1> <HR2><HR1>:<MN2><MN1>:00

00h                                                MN2|MN1
01h                                      HR2|HR1
02h                              DM1|DW
03h                     MO1|DM2
04h          YR1|MO2
05h  ?|YR2
WD Weekday
1h Monday
2h Tuesday
3h Wednesday
4h Thursday
5h Friday
6h Saturday
7h Sunday

Timezone

TZ TZ Offset
0Ch +1200
...  
01h +0100
00h +0000
FFh -0100
...  
F4h -1200

Log Interval

LI Interval
0h 1-minute
1h 5-minute
2h 10-minute
3h 15-minute
4h 20-minute
5h 30-minute
6h 1-hour
7h 2-hour
8h 4-hour*
9h 6-hour*
Ah 8-hour*
Bh 12-hour*
Ch 24-hour*

Log Count

BCD formatted log count (displayed as-is on LCD to represet no. of unread entries):

<LC4><LC3><LC2><LC1>

Gets incremented on each measurement recording. Is usually reset to zero by data recorder, so that this field represents the number of unread log records.

When the last record is written which fits into the log area, the <OVF> bit gets set - i.e. the log buffer overflows - and the very first record is overwritten next. The log counter is not incremented anymore.

Calibration Data:

0000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
        Ti    T1    T2    T3    T4    T5 Fi F1 F2 F3 F4
0000020 00
        F5

00 -> 0

90 -> -10

10 -> +10

0000020    70 10 70 10 70 10 70 10 70 10 70 10
           H/L F Alarms

T-Alarms:

0000020                                        00 00 06
0000030 00 40 00 00 06 00 40 00 00 06 00 40 00 00 06 00
0000040 40 00 00 06 00 40 00 00 06 00 40

2Dh  00                            rsvd
2Eh  00                       Tmax
2Fh  06              rsvd|Tmax
30h  00     Tmin|rsvd
31h  40 Tmin

Sensor Ids:

Addr. Section Bit Format
7 6 5 4 3 2 1 0
4Bh Sensor Ids Sensor Id 1 UINT8
4Ch Sensor Id 2 UINT8
4Dh Sensor Id 3 UINT8
4Eh Sensor Id 4 UINT8
4Fh Sensor Id 5 UINT8
50h Sensor valid ? SV5 SV4 SV3 SV2 SV1 bitfield 
0000040                                  4c 00 00 00 00
0000050 01

Ringbuffer Config:

used by data logger software for housekeeping

0000050    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
0000060 ff ff ff ff

Log Area

all BCD coded

Timestamp

Byte  0: MM (0xFF = record not written yet)
Byte  1: HH
Byte  2: dd
Byte  3: mm
Byte  4: yy

Encoding of T

BCD coded:

AAAh = N/A
XXXh = (XXX-300)/10 C

Encoding of H

BCD coded:

AAh = N/A
XXh = XX RH%

Record Lengths

SC Record Length Capacity
0 10 3266
1 10 3266
2 13 (12.5) 2512
3 15 2177
4 18 (17.5) 1814
5 20 1633

for I+5:

Byte  5:                  Tin
Byte  6:           T1|Tin
Byte  7:        T1
Byte  8:    Hin
Byte  9: H1

Byte 10:                   T2
Byte 11:             H2|T2
Byte 12:       T3|H2

Byte 13:    T3
Byte 14: H3

Byte 15:                   T4
Byte 16:             H4|T4
Byte 17:       T5|H4

Byte 18:    T5
Byte 19: H5

EOF Marker

5a2f @ 0x7ffb

References

https://oss.inqnet.at/trac/klimalogger/

http://members.home.nl/xbasic/01c2249c770e62101/index.html

http://www.atmel.com/dyn/resources/prod_documents/doc0670.pdf