Waterpump

This project is an automatic system for watering plants. Everyday, pumps are switched on for a few seconds to provide enough water to some plants. The device can be controlled by sending SMS to change the schedule or water plants. In addition, a small push-button is present to water plants immediately.

Build and flash instructions

Prerequisites

You need to install the ARM embedded toolchain and JLink Software and Documentation Pack.

SIM card configuration

The SIM card might need to be unlocked. The default PIN is set to 1234 by the SIMCARD_PIN macro that can be overriden.

To retrieve time from network, the firmware needs the APN name which depends on your network provider. The macro SIM800_APN_NAME is currently set to "free" in the Makefile because I am using a SIM card from Free Mobile. Feel free to change it.

Commands

There are two types of build: release and debug.

To build the project, run one of these commands:

$ make                  # BUILDTYPE set to release
$ BUILDTYPE=release make
$ BUILDTYPE=debug make

Connect the board to a SEGGER debug probe and run these commands to flash or debug the firmware:

$ make flash-target                 # Flash release firmware
$ BUILDTYPE=debug make flash-target # Flash debug firmware
$ BUILDTYPE=debug make debug-target # Start debugging firmware

Building hardware

In hardware folder, there are Gerber files sent to JLCPCB for each revision of the board. I recommend that you build the latest revision of the board. Components can be bought on RS online.

Issues with rev1 board

• SIM800L Footprint is incorrect
• No mounting holes
• micro USB connector is too far away from the side of the board
• Power circuit for SIM800L is not working properly. Large polarized capacitors are missing on the input and output of the LDO voltage regulator. The regulator is not able to handle load transients fast enough, causing the SIM800L to brown out.

Issues with rev2 board

• SIM800L footprint is still incorrect ! Although it is easier to insert the module in pin headers than on rev1.
• micro USB connector should be replaced by a barrel connector because USB cables should not be used to provide 3A.

Power requirements

The GSM module can use up to 2A and each pump should not use more than 1A due to the choice of MOSFET transistors (especially on rev 2). For this reason, I recommend powering this board with a 5V 3A power supply. Alternatively if you are using only 2.5W pumps, a 5V 2.5A can be used.

Switching on water pump

Both pumps are switched on in sequence for 3 seconds each if the push button is pressed or if the GSM modules receives a text message starting with "WATER ALL". If you only want to enable pump 1 or 2, send text message "WATER 1" or "WATER 2".

SMS commands

Command	description	examples
BUTTON <duration>	Configure for how long each pump is enabled when button is pressed	BUTTON 5
WATER <pump_index>	Turn on one pump for DEFAULT_PUMP_DURATION seconds (default: 3s)	WATER 1, WATER 2
WATER ALL	Turn on both pumps, each for DEFAULT_PUMP_DURATION seconds (default: 3s)	WATER ALL
SCHEDULE <index> STOP	Disable a schedule	SCHEDULE 0 STOP, SCHEDULE 1 STOP
SCHEDULE <index> <hour>:<min>:<sec> <duration> ALL	Turn on both pumps once per day	SCHEDULE 0 19:04:57 3 ALL
SCHEDULE <index> <hour>:<min>:<sec> <duration> <pump_index>	Turn on a pump once per day	SCHEDULE 2 06:43:00 7 1, SCHEDULE 3 06:43:00 9 2
SCHEDULE STATUS	Request schedule status	SCHEDULE STATUS