GardenaBWP

I started to reverse engineering the Gardena Battery Rain Water Tank Pump 2000/2 in 2022. Unfortunately, I found out that the microcontroller cannot be read out (https://electronics.stackexchange.com/questions/629883/gardena-battery-rain-water-tank-pump-2000-2-swd-interface). Therefore, I have temporarily suspended the project.

I have a garden and would like to water it automatically with rain. For this I bought a «Gardena Battery Rain Water Tank Pump 2000/2» and would like to control via an ESP microcontroller.

Gardena Battery Rain Water Tank Pump 2000/2 18V P4A - Article No. 14602

• Website: https://www.gardena.com/int/products/lawn-care/grass-trimmers/system-battery-p4a-pba-18v-45/970508501/
• Manuel: https://www.gardena.com/tdrdownload//pub000081324/doc000149307 or Manuel

Gardena System Battery P4A PBA 18V/45 - Article No. 14903-20

• Website: https://www.gardena.com/int/products/watering/pump/battery-rain-water-tank-pump-2000-2-li-18-ready-to-use-set/970511001/
• Manuel: https://www.gardena.com/tdrdownload//pub000081354/doc000149497 or Manuel

Reverse Engineering

Akku

Description	Pin
Plus (+)	1
NTC	2
ID	3
Minus (-)	4

Control Panel

After opening the control panel, I found that the board is molded in black plastic.

Label Description: HW: 3.1.4A3 | SW: 3.1.0 | 20210819

PCB

I removed the plastic from the board.

• www.leli.asia
• E123995
• LKS-181P_V3.1.0_20200806
• A109742 2021 04 12

MCU

Nuvoton NuMicro ML51TC0AE

• https://www.nuvoton.com/products/microcontrollers/8bit-8051-mcus/low-power-ml51-series/ml51tc0ae/
• https://www.nuvoton.com/export/resource-files/DS_ML51_ML54_ML56_Series_EN_Rev2.02.pdf or Datasheet

6-Pin Header

Nuvoton NU-Link + TX

Description	Pin	Pin	Description
TX	1	2	GND
VCC	3	4	DAT
RST	5	6	CLK

• https://www.nuvoton.com/export/resource-files/UM_Nuvoton_Nu-Link_Debug_Adapter_EN_Rev1.01.pdf

Logic Analyzer: TX

Baudrate: 9600 8N1

Recived Data: TX

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

HEX and ASCII

First Byte	?	Batt. V	Batt. A	Batt. Temp	Error	SMO	Batt. Type. Rev	Software Ver.	Temp	Batt. Type	Auto Incremental	Checksum	Last Byte
FB		U	I	TA	Err	SMO	BTR	SVN	TS	BT	AI	CS	LB
0xFE	2	00.00	00.00	000.0	00	023	000k0	03.10	000.0	0_0	000002100	0x18	0xFD
0xFE	2	20.41	00.00	025.4	00	023	047k5	03.10	025.7	3_1	000002101	0x19	0xFD
0xFE	2	20.40	00.00	025.4	00	023	047k5	03.10	025.8	3_1	000041102	0x13	0xFD
0xFE	2	20.40	00.00	025.4	00	023	047k5	03.10	025.8	3_1	000041103	0x12	0xFD

Checksume: To create the checksum, start reading after the first byte, end before the checksum byte and calculate the checksum using the CheckSum8 Xor algorithm.

HEX and ASCII without BATTERY DATA CABLE

FB		U	I	TA	Err	SMO	BTR	SVN	TS	BT	AI	CS	LB
0xFE	2	00.00	00.00	000.0	00	023	000k0	03.10	000.0	0_0	000002100	0x18	0xFD
0xFE	2	20.46	00.00	-20.0	00	023	999k9	03.10	024.6	0_0	000002101	-	0xFD
0xFE	2	20.46	00.00	-20.0	07	023	999k9	03.10	024.6	0_0	000031102	-	0xFD

HEX and ASCII without BATTERY DATA CABLE AND PUMP

FB		U	I	TA	Err	SMO	BTR	SVN	TS	BT	AI	CS	LB
0xFE	2	00.00	00.00	000.0	00	023	000k0	03.10	000.0	0_0	000041000	0x1E	0xFD
0xFE	2	20.46	00.00	-20.0	00	023	999k9	03.10	026.1	0_0	000041001	-	0x02

HEX and ASCII without PUMP

FB		U	I	TA	Err	SMO	BTR	SVN	TS	BT	AI	CS	LB
0xFE	2	00.00	00.00	000.0	00	023	000k0	03.10	000.0	0_0	000001000	0x1A	0xFD
0xFE	2	20.39	00.00	025.4	00	023	047k5	03.10	025.7	3_1	000041001	0x11	0xFD
0xFE	2	20.39	00.00	025.4	00	023	047k5	03.10	025.8	3_1	000041002	0x12	0xFD
0xFE	2	20.39	00.00	025.4	00	023	047k5	03.10	025.8	3_1	000041003	0x13	0xFD

HEX and ASCII without PUMP und Power Up

FB		U	I	TA	Err	SMO	BTR	SVN	TS	BT	AI	CS	LB
0xFE	2	00.00	00.00	000.0	00	023	000k0	03.10	000.0	0_0	000002100	0x18	0xFD
0xFE	2	20.40	00.00	025.3	00	023	047k5	03.10	025.7	3_1	000002101	0x11	0xFD
0xFE	2	20.39	00.00	025.4	00	023	047k5	03.10	025.8	3_1	000002102	0x1F	0xFD
0xFE	2	20.39	00.00	025.4	08	023	047k5	03.10	025.8	3_1	000032103	0x15	0xFD
0xFE	2	20.39	00.00	025.4	08	023	047k5	03.10	025.8	3_1	000032103	0x15	0xFD

Notes

Gardena

• https://gitlab.com/nbrgmn/wall-e-esp8266-automower/-/tree/develop
• https://www.roboter-forum.com/index.php?thread/12310-wlan-anbindung-gardena-r40li-hausautomatisierung-fernbedienung-etc/&pageNo=2
• https://www.youtube.com/watch?v=DqCoxzLTGXg&t=567s

Arduino Logic Analyzer

• https://github.com/gillham/logic_analyzer
• https://github.com/jawi/ols

Arduino Baudrate Finder

• https://github.com/Sjord/autobaud

Checksum Calculator

• https://www.scadacore.com/tools/programming-calculators/online-checksum-calculator/

Battery Hack Sheet

• https://docs.google.com/spreadsheets/d/1y2jpoUwTOCbt6W3V7BTANON0qFRX7MPgF3T8NVuv8oo/edit#gid=698376076

STACKOVERFLOW

• https://electronics.stackexchange.com/questions/617385/gardena-battery-rain-water-tank-pump-2000-2-uart-interface
• https://electronics.stackexchange.com/questions/629883/gardena-battery-rain-water-tank-pump-2000-2-swd-interface