This make project is a custom LEGO® creation to control the gate of a flood barrier model by a microcontroller with sensors, actuators and LEGO Power Functions. (LEGO® is a trademark of the LEGO Group)
- To create a model of a flood barrier with a gate, in the style of the "Sperrwerk Wedeler Au" (barrier between the German rivers "Elbe" and "Wedeler Au")
- To obtain, in regular intervals, real tide data from the river "Elbe"
- To control the gate depending high tide (flood) level = close the gate at Abs NHN river level threshold reached else open the gate
- To display in a large number display the river "Elbe" level Abs NHN = Absolute Standard Elevation Zero Level (cm)
- To display information in a small display, i.e. Abs NHN (cm), Rel PNP = Relative Tide Gauge Zero (cm), PNP=Tide Gauge Zero (m), Tide Ebb or Flood, Gate State Open or Close
- To remote control the gate
- To publish tide data
- To have fun exploring and creating technical type of digital custom creations
Note: This make project is for private use only.
- Use as microcontroller an ESP8266 microcontroller
- Use standard LEGO components (LEGO® is a trademark of the LEGO Group)
- Minimize LEGO brick modifications
- LEGO Case with modular components
- Develop the microcontroller code with B4R
- Develop client solutions in Node-RED and B4J
- 1x NodeMCU (ESP-12E) with Development Board
- 1x Infrared Transmitter (KY-005)
- 1x 4-Digit Display (Catalex 4-Digit Display)
- 1x OLED Display
- 1x REED Switch (KY-021)
- 1x Push-Button
- 1x LED Red
- 1x LED Green
- LEGO Power Functions Light (8870)
- LEGO Power Functions IR Speed Remote Control (8879)
- LEGO Power Functions Battery Box (8881)
- LEGO Power Functions M-Motor (8883)
- LEGO Power Functions IR Receiver (8884)
- Various LEGO Bricks and LEGO Technic parts
- Various wires
- Arduino IDE 1.8.9 or higher
- B4R 2.8.0 or higher
- Node-RED 0.20.7 with Node-RED Dashboard 2.16.3
The model is built of LEGO® Bricks, LEGO® Technic™, LEGO® Power Functions controlled by a microcontroller with sensors & actuators attached. The microcontroller connects to the WiFi network (hardcoded SSID & Key for now). The river "Elbe" level information is obtained every 5 minutes, via HTTP from the German webservice PEGELONLINE.de.
The HTTP JSON response is parsed to get the river level current measurement "Relative PNP" and the reference value "PNP" which are used to calculate the "Abs NHN". The "Abs NHN" value is compared to the previous "Abs NHN" value to determine the tide Ebb or Flood. In addition, the gate state open or closed is set according river level threshold reached (=gate is closed) or below threshold (=gate is open). The threshold is initially hardcoded, but can be set via client (i.e. Node-RED) using MQTT. If the threshold is reached, the gate closed if open else the gate opens if closed.
On every 5 minute update cycle, controlled via timer, the 4-Digit is display is set with the "Abs NHN" cm and the OLED display with the river levels "Abs NHN", "Rel PNP", "PNP", Tide Ebb or Flood, Gate State Open or Closed. LED signals are used to indicate i the gate is moving (two white lights, the motor is running), LED red if the gate is closed, LED green if the gate is open.
The initial position of the gate is closed and is set via LEGO Power Functions IR Remote Control. A push-button enabled to open or close the gate manually.
MQTT messages are published with the river level information (can be used to display a Node-RED Dashboard with gauges and charts), but also to control the gate, move the motor or set the river level threshold.
See also TODO.md. Ideas in mind planned for any next version.
- Display real signal depending gate state
- Requires additional LEDs (i.e. gate open: 1 white + 2 red; gate closed: 2 red). There are no GPIO pins left = requires multiple LED on one pin solution (i.e. Shift Register 74HC595 or MAX7219)
- REED switch to control gate close position (instead of using timer from open to close position)
- Requires additional GPIO with pullup There are no GPIO pins left = no solution yet found
- Configuration parameter setting EEPROM using B4J client or Node-RED: WiFi SSID&Key, Gate Close Threshold, MQTT Server IP
- MQTT parsing using extenal library instead of using ByteConverter with Split & IndexOf methods
- Multi push-buttons to control the gate PF M-Motor open, close, reverse, forward
- Request online sea weather forecast to display on OLED row 6 (wind,temperature)
IR Sender=NodeMCU
Signal=D2 (GPIO4) yellow
GND=GND black
TM1637=NodeMCU
CLK=D6 (GPIO12)
DIO=D7 (GPIO13)
VCC=3V3
GND=GND
OLED (I2C)=NodeMCU
SDA=D4 (GPIO2)
SCL=D5 (GPIO14)
VCC=3V3
GND=GND
I2C Address: 0x3c
REED Switch (open gate)=NodeMMCU
S=D1 (GPIO5)
VCC=3V3
GND=GND
Push-Button (gate switch)=NodeMCU
S=D3 (GPIO0)
GND=GND
LED GATE STATE SIGNAL=NodeMCU
LED GREEN (gate open)=RX (GPIO03)
LED Red (gate closed)=green=D8 (GPIO15)
GND=GND
In regular intervals, a HTTP download request (url hardcoded) is used to get the river level information from a German webservice PEGELONLINE.wsv.de. The HTTP response is a JSON string which is parsed (bit quick and dirty using various ByteConverter methods, i.e. Split,IndexOf and others with StringFromBytes to get the various river "Elbe" values. Sample extract from the HTTP JSON Response:
{...
"timeseries": [
{
"currentMeasurement": {
"timestamp": "2019-09-15T11:50:00+02:00",
"value": 393.0,
"trend": 1,
"stateMnwMhw": "unknown",
"stateNswHsw": "unknown"
},
"gaugeZero": {
"unit": "m. ü. NHN",
"value": -5.006,
"validFrom": "2001-11-01"
}
}
]
...}
The keys used are
timerseries[0].currentMeasurement.value for Abs PNP.
timerseries[0].gaugeZero.value for PNP.
In method HTTP JobDone, the values are extracted (snippet) using the ByteConverter:
Dim bc As ByteConverter
For Each value() As Byte In bc.Split(jobresponse, """value"": ")
If bc.IndexOf(value, "trend".GetBytes) > 0 Then
riverlevelRELPNP = bc.StringFromBytes(bc.SubString2(value, 0, bc.IndexOf(value, ",".GetBytes)))
End If
If bc.IndexOf(value, "valid".GetBytes) > 0 Then
riverlevelPNP = bc.StringFromBytes(bc.SubString2(value, 0, bc.IndexOf(value, ",".GetBytes)))
riverlevelPNPS = bc.StringFromBytes(bc.SubString2(value, 0, bc.IndexOf(value, ",".GetBytes)))
End If
Next
riverlevelABSNHN = riverlevelRELPNP + (riverlevelPNP * 100)
Note: As mentioned, seeking for a proper JSON parse solution (probably with an additional library).
A connection is made to a MQTT Broker (IP address hardcoded) running on a Raspberry Pi 4 (mosquitto broker). The B4R program publishes messages:
topic floodbarrier/riverlevelabsnhn ; payload NN cm
topic floodbarrier/riverlevelrelpnp ; payload NN cm
topic floodbarrier/riverlevelpnp ; payload NN m
topic floodbarrier/riverleveltide ; payload Flut or Ebbe
topic floodbarrier/gatestate ; payload 0 (closed), 1 (open)
The B4R program subscribes to messages:
topic floodbarrier/gateopen ; payload n/a - topic triggers action to open the gate.
topic floodbarrier/gateclose ; payload n/a - topic triggers action to close the gate.
topic floodbarrier/gatemotorfwd ; payload n/a - topic triggers action = move PF M-Motor forward with lowest speed (FWD).
topic floodbarrier/gatemotorrev ; payload n/a - topic triggers action = move PF M-Motor reverse with lowest speed (REV).
topic floodbarrier/gatemotorbrk ; payload n/a - topic triggers action = break (=stop) the PF M-Motor.
topic floodbarrier/gatestate ; payload 0=closed,1=open - for tests only.
topic floodbarrier/gatestatethreshold ; payload NNN in cm - changes the initial value of 210 cm.
topic floodbarrier/riverlevel ; payload csv string: absnhn,relpnp,pnp,tide - for tests only to set the River "Elbe" levels via MQTT (by f.e. Node-RED) instead of HTTP.
The model is built using mix of LEGO classic & technic bricks. No modifications made nor soldering of components.
(abbreviated as PF)
PF V Battery -> IR Receiver Green Output -> M-Motor | Lights
The PF M-Motor controls opening or closing the gate and is used to set the initial position of the gate (this via IR Speed Remote Control). To avoid moving the gate too fast, a gear box has been built between the M-Motor and the gate. The gear box has three times gear ratio of 3. This has been accomplished by using three times 8 and 24 teeth gears. The M-Motor has a speed of ~220RPM. Speed reduction calculation (numbers rounded): S1=220; S2=(220x8)/24=73; S3=(73x8)/24=24; S4=(24x8)/24=8 RPM.
When the PF M-Motor is running to either open or close the gate, the PF Light is on (two white lights).
The initial state of the gate must be set to closed. The REED switch has state 1 (true).
When the gate opens, the PF M-Motor is running Reverse (turning left, speed REV2) for 4 seconds (with speed FWD2 defined in library rPowerFunctions). When the gate closes, the PF M-Motor is running Forward (turning right, speed FWD2) till the REED switch gets state 0 (false) as recognised by the magnet, placed on the back of the gate. The 4 seconds are controlled by a timer, i.e. 4 cycles a 1000 ms (aligned with the PF M-Motor speed FWD2). Note: If the PF M-Motor speed is changed (i.e. running slower FWD | REV), then adjust the timer cycles to ensure the gate holds at the right position.
The gate state are using global vars:
'open (gateState=1),closed (gateState=0)
Private gateState As Byte = 0
'ABSNHN >= 210 close the gate else open
Private gateStateThreshold As Int = 210
The initial threshold, i.e. 210 m, is checked at every river level update timer cycle. If reachd the gate is closed or if below, the gate is opened. The initial threshold is given by information from the real flood barrier - in practise the gate is (already) manuall closed by ~180 cm. The threshold can be set via MQTT message, i.e. Node-RED flow with Dashboard UI.
topic floodbarrier/gatestatethreshold ; payload NNN in cm
Note: Considering using a second REED switch to stop the PF M-Moter for gate closure. Issue: no pullup GPIO pins available.
The display shows the river "Elbe" level in "Abs NHN" in cm. This is a 3 digit positive or negative value. The library rTM1637 is used to set the value with the minus sign. If the value is negative, then the method SetSegments displays the minus sign. The minus sign is defined as
Private displaySegments(1) As Byte
To display the minus sign = the segment G bit set, all other segents are not set. ParseInt with radix 2 for the string with length 8 holding the bits for the segment
displaySegments(0) = Bit.ParseInt("01000000",2)
The 4 digits used: most left set by SetSegments, the other 3 are set most right starting at 2 pos (=index 1) [0][1][2][3] > [minus or empty][N][N][N]
If riverLevel < 0 Then
'Display 3 digits starting at pos 1
tmRiverLevel.ShowNumberDec2(Abs(Round(riverLevel)), False, 3, 1)
'Display segment starting leftmost - only one segment is used to show the - sign
tmRiverLevel.SetSegments(displaySegments,0)
Else
tmRiverLevel.ShowNumberDec2(Abs(Round(riverLevel)), False, 4, 0)
End If
The display shows river "Elbe" various levels + Tide (Ebb or Flood; German text used Ebbe, Flut) + Gate State (Open or Closed; German text used AUF, ZU). The B4R library rESPOLED1608 is used to display 8 rows (0-7) with up-to 16 columns (0-15). Each time the display is updated, the rows are cleared (tmDisplay.Clear) prior printing new rows.
Row 0: Not used
Row 1: Abs NHN in cm
Row 2: Relative PNP in cm
Row 3: PNP in m
Row 4: Tide: Ebbe or Tide: Flut
Row 5: Tor: AUF or Tor: ZU
Row 6: Not used
Row 7: Not used - but can be used to display Version
In case of an error, the error message is displayed on row 1.
Note: The columns start at position 1 and not 0.
Log and control using Node-RED running on a Raspberry Pi 4.
The source code is well documented. See files b4r-source.zip, b4r-additional-libraries.zip, node-red.flow.
Board NodeMCU 1.0 (ESP-12E Module) with 4MB. IDE Options > Configure Process Timeout set to 120.
Arduino IDE Add to File > Preferences > Additional Board Managers URLs:
https://dl.espressif.com/dl/package_esp32_index.json,http://arduino.esp8266.com/stable/package_esp8266com_index.json
- Turn on the LEGO Power Functions Battery Box
- Set Gate to CLOSE position using the LEGO Power Functions IR Remote Control or Push-Button
- Turn the LEGO Power Functions M-Motor OFF
- Compile & Upload
- Turn the LEGO Power Functions M-Motor ON
Note: It might happen from time-to-time, that an "unable to upload" error occurs. Try compiling again or reset the NodeMCU.
- Turn the LEGO Power Functions M-Motor ON
- Set the Gate to CLOSE position using the LEGO Power Functions IR Remote Control
- Power ON the NodeMCU
- Set the Gate to CLOSE position using the LGO Power Functions IR Remote Control or Push-Button or Node-RED Client
- Turn the LEGO Power Functions Motor OFF
- Power OFF the NodeMCU
- Anywhere Software for providing B4R (and of course the whole B4X suite) Info
- Friends-of-Fritzing foundation for fritzing Info
- jurriaan for the LEGO Power Functions library Info
- remoteme for the ESP8266 OLED library Info
- PEGELONLINE.wsv.de for providing river level information services.
Also published at Anywhere Software B4R Forum.
GNU GENERAL PUBLIC LICENSE Version 3, 29 June 2007