Teensy-RV-Leveling-Helper

Teensy RV Leveling Helper using Teensy 4.0 + BMA400 Triple Axis Accelerometer Breakout + ILI9341 Color 320x240 TFT Touchscreen display + NRF24L01 radio

This project came about after we acquired a used RV motorhome & I quickly grew tired of the following process of attempting to level the RV:

1. park the RV on a particular site
2. look at the bubble level on the kitchen counter to determine "level or not"
3. make/revise my best guess as to how many blocks are required on each wheel to attain "level"
4. drive the RV up on the best guess number of blocks
5. if the RV is "level", then you're DONE !!
6. if the RV is not yet "level", then drive the RV down off of the best guess number of blocks
7. goto 3) above & repeat several times (until either we're close enough, or I get fed up, whichever comes first)

Using the TRLH makes this process much more convenient & quick as follows:

1. park your RV where you want it to ultimately rest for the duration of your stay
2. apply power to the inside TRLH & place it on the kitchen counter inside the RV (which provides a non-moving reference plane for the entire RV)
3. if you are using a second TRLH as a remote display, apply power to the remote TRLH (the two units will establish sync over the radio & the remote unit will ignore its own accelerometer data, and will instead perform all leveling calculations using the accelerometer data received from the inside TRLH over the NRF24L01 radio - NOTE: if you're not using the remote TRLH, the inside TRLH will still operate as a single unit)
4. take note of the leveling solution displayed (indicating results of calculating how many inches to raise any of the wheels in order to bring the RV to a perfectly level position)
5. back the RV away sufficiently to leave room to put the ramps into place
6. build and place the required ramps (using 1" blocks) to raise the wheels as indicated
7. drive the RV up onto the newly built leveling ramps
8. verify that the TRLH now shows 0" for each wheel - LEVELING SUCCESS !! (Note that anything within 1" of level is sufficient for the comfort of the occupants, as well as for the equipment, primarily the refrigerator)
9. sit back & enjoy a cold drink of your choice

This project incorporates the following:

HARDWARE:

  Teensy 4.0
     available from PJRC.com https://www.pjrc.com/teensy-4-0/

  ILI9341 Color 320x240 TFT Touchscreen display
     available from PJRC.com https://www.pjrc.com/store/display_ili9341_touch.html

  HiLetgo NRF24L01+ Wireless Transceiver Module 2.4GHz
     available from https://www.amazon.com/gp/product/B00LX47OCY

  BMA400 Triple Axis Accelerometer Breakout
     available from Sparkfun https://www.sparkfun.com/products/21208

  PowerBoost 1000 Charger - Rechargeable 5V Lipo USB Boost @ 1A - 1000C
     available from Adafruit https://www.adafruit.com/product/2465
     
  Lithium Ion Polymer Battery - 3.7v 2500mAh
     available from Adafruit https://www.adafruit.com/product/328

This project uses touchscreen input & color display to create a visual (graphical) indication of how many inches of leveling blocks are required to be put under each wheel of an RV to level it

This project uses the ILI9341_t3 library, which has been optimized for use with the Teensy TFT display, as well as the XPT2046_Touchscreen.h touchscreen library for that same display

This project (optionally) uses the NRF24L01 wireless transceiver module to allow two TRLH units to communicate, using one as the inside unit taking measurements, and the other as a remote display

This project specifically uses the SparkFun BMA400 support library (SparkFun_BMA400_Arduino_Library.h) which can be added using the Arduino IDE library manager.

This project allows & stores configurable wheel base (front to back wheels distance) from 60" to 255".

This project allows & stores configurable wheel distance (front wheels, left to right distance) from 60" to 84".

Internet reference (with equation derivation) for transforming accelerometer x,y,z vector data into pitch & roll angles:

  https://mwrona.com/posts/accel-roll-pitch/

The specific DPDT switch that I use for power control (& for which the 3D printed case is designed) is the Carling Technologies 62115929-0-0-V, available from digikey as part number 432-1252-ND (https://www.digikey.com/en/products/detail/carling-technologies/62115929-0-0-V/3025077).

An Adafruit microUSB panel mount extension cable Product ID 3258 (https://www.adafruit.com/product/3258) is mounted on the side wall of the case. The cable is split such that the USB 5VDC line connects to the USB input pin on the Adafruit PowerBoost 1000C to provide power & battery charging, while the remaining GROUND, D-, & D+ signals connect to the microUSB connector on the Teensy to allow (re)programming without opening the case.

This project implements the following:

  1) read the XYZ vector from the BMA400 triple axis accelerometer breakout
  2) use the XYZ vector to calculate PITCH and ROLL values for the current plane of the RV/trailer orientation
  3) use the calculated PITCH and ROLL values to determine the highest wheel/point (which will not require any blocks)
  4) use the calculated PITCH and ROLL values to determine the number of inches of blocks required for the remaining wheels/points to achieve "level"
  5) update the display with the current results once per second (& average all values otherwise)
  6) repeat

LATEST UPDATE (version 1.3 dated 03/25/2024 @1940):

Now, two units can be used & they talk to each other using NRF24L01 wireless modules. The first unit powered on will assume that it is the "INSIDE" unit (which is actually reading its onboard BMA400 accelerometer & displaying the leveling recommendations from the calculated pitch & roll). The second unit will assume that it is the "OUTSIDE" unit (which is ignoring its onboard BMA400, and is instead displaying the leveling recommendations calculated using the pitch & roll data received over the NRF24L01 wireless link from the "INSIDE" unit). This way, leveling can be achieved without the need for running back & forth between inside (to look at the Teensy-RV-Leveling-Helper) & outside (to make adjustments). Any unit can also be used by itself...it does not have to have a partner to work. The latest firmware also automatically detects the lack of the NRF24L01 module & operates successfully without the radio as a standalone unit.

OPERATIONAL MODE:

This project can be switched between the following primary modes of operation:

• RV mode (four points of balance/leveling = four wheels)
• Trailer mode (three points of balance/leveling = two wheels and the hitch)
• Bubble mode (traditional 2-D bubble level)

MECHANICAL ASSEMBLY & CALIBRATION:

For information on mechanical assembly and/or calibration, see the "readme" file in the "photos" folder.

ORDERING INFO:

The compact PCB is available from OshPark here: https://oshpark.com/projects/CN9rpz97/order

CONTACT INFO:

If you have any questions, suggestions for improvement, and most especially any bug reports, please contact me at kd5rxt@arrl.net