Picorder 2

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The current prototype test rigs Unit 00 (left) and Unit 01 (rig)


The TR-109 Picorder 2 project aims to develop and produce a portable, self contained, Raspberry Pi based sensor data acquisition platform in the shape of a Tricorder from Star Trek the Next Generation.

It is the successor to the original Picorder. Originally the projects goal was to make a single Tricorder replica, but the Picorder 2 project has slowly lead to a set of standards for the Picorder family of devices I want to make.

Latest update:

Prototype 00 is now complete. Prototype 01 is under construction.


To Do:

-Finish Prototype 01

-Finish database groundwork.

-Revise sensor board to account for missing connections on 74HC595, and floating pins on BME680.

-Revise main board to account for disconnected ground fill.


Software

Picorder 2 will use PicorderOS a python library that unifies a number of different modules under a custom user interface.

Hardware

Prototype Units

Unit 00

Unit 01

Unit 02

This final prototype will be used to finalize the means of assembly. It will likely be the last Picorder of this series.

PCBs

Custom PCBs are being produced for this project, they are designed in KiCad and will be available to the public when finished.


MainBoard

The Main Board hosts all the control electronics for capacitive touch, LED indication (operator facing), door close hall effect sensors, and graphical and audio output.

SensorBoard

The Sensor Board hosts all the control electronics for LED indicators (forward facing) as well as any sensors that the device will address.


CPU

Raspberry Pi Zero W
Like my original picorder, the TR109 will be by a Raspberry Pi Zero W. Power consumption was a major problem with the first Picorder, I have found a really good article on some ways to reduce power consumption.

Sensors

The intention of the Picorder project is to create a device that can accept any arbitrary sensor arrangement and map it (assuming the appropriate software has been written to support it). But the TR109 PCBs and case is planned to be capable of supporting 3 main sensor packages on it forward facing array:

Bm860 VOC, Temp, Humidity, Pressure sensor
The BME680 is a basic environmental sensor. VOC is a nice added feature that adds some real world use, but interpreting the reading requires some analysis. This sensor will mostly be to provide ambient environmental information. For prototyping I found a good guide for how to connect it to a Pi and used Adafruits circuitpython library to integrate it into PicorderOS. Because the BME680 includes 4 seperate data sources in one device I am making it the "base model" sensor for this project. I will direct most of my efforts to make the best experience when using this sensor.
AMG8833 IR Thermal Camera
The AMG8833 is a relatively low resolution and low range thermal camera. It will basically only be useful for detecting dramatic temperature difference. It is also relatively cheap and so I am going to include it. This sensor will provide quasi-accurate contextual temperature information at range.
MLX90614 Non Contact Thermometer
A cheap and accessible non contact thermometer. This sensor provides accurate specific temperature readings at range. I've managed to find Adafruits own circuitpython implementation and this page looks fruitful too.

Other Options

Other possible sensor options include

MiCS6814
I was turned onto the idea of an 8 gas sensor by the ODROID-GO Ticorder project where they used this IC to measure carbon minoxide, nitrogen dioxide, hydrogen, ammonia, methane, propane, and iso-butane. I found a great blogpost on some ways to use it. Because it is an analog sensor I would need to use an ADC and some way to connect it to the Pi.
An EMF sensor of some kind.
Probably a resistor on an ADC to give me basic environmental electrical readings. I found this site that shows you how you can use at AT tiny as an i2c device, which I could use with this guide to make a small EMF detector to read low frequency interference. Another option suggested to me by reddit user 2CNK is to use an Elektrosluch like device to convert ambient EMI into some kind of data. I found a circuit example that might prove useful.

Audio

Audio was missing on the Picorder 1, I'd like to add it to this picorder if possible. I found a great instructable post by rgrokett for an audio solution that might work. In the comments I found a link to the raspberry pi forums that has some updated dtoverlay arguments that work on the newer pi os.

Shell

Picorder 2 will officially support a standardized 3D printed enclosure. This file will likely be included with picorderOS software. The case is designed to be several pieces that fasten together.

Rev1b.png Picorder2 3d plan.png

General Design

Recently I redesigned the shell on the Picorder to use a more accurate style of enclosure

The current design of the Picorder 2 shell incorporates a main body and chassis with a lower door. All of the major components are housed in the main body with the lower door being used for extra buttons and battery storage. The mainboard PCB is attached to the chassis, along with the Raspberry Pi, the sensor board and all internal lighting. The chassis slides in and out of the main body on tracks, and is secured to the main body with 4 M2 screws.

Custom printed stickers are used to add the labeled button areas.

Before I decided to use a 3D printed enclosure there were two "off the shelf" options that seemed suitable for the shell

Mark 7 Tricorder Replica
I've acquired a prop replica kit for the mark 7 tricorder from Stapleton Productions.
1993 Playmates Tricorder Toy
For the prototype, this is easy to get and modify.

And I hope to be able to maintain support for those ideas as I continue developing the P2.

Input

CAP1208 Capacitive Touch Sensor IC
Originally I was going to use the MPR121 but since the chip is discontinued I decided to look for other options. I became interested in a chip I saw mentioned in the documentation for a pimoroni product; the CAP1208.
The chip includes a number of features like hold detection, and has an interrupt pin. The entire CAP1xxx series is supported by a library maintained by Pimoroni and so it seems like a great choice for this project.
MPR121 Capacitive Touch Buttons <<OBSOLETE>>
It turns out this component has been discontinued.
Controller to use small metal pads for capacitive buttons for inputs. I found a good guide and software info for the Pi here.

Display

TFT ST7735.png

Generic ST7735 LCD Display
I've been using screens with of this type with the Luma.lcd python module. I bet you could also use FBTFT to use it as a display target (requires additional software modifications, but makes it usable as a small computer). The display I found (pictured) had no pins listed as MOSI or MISO (for SPI) but I found a pin chart in the Luma docs that helped.


I had considered the idea of also offering a low cost screen, but the availability is poor.:

5110 3310 monochrome LCD.jpg

Nokia 5110 LCD screen
To provide low power information output to the user, and maybe to play some snake. I looked in a number of places to find a good guide on how to connect the Adafruit part I have with various descriptions around the web. I found this guide to have some important information, but the wiring information seemed incorrect. This guide lays out how to connect the screen properly..

LEDS

As with the original picorder I want to make sure that this one has a feel of the actual prop. the TOS tricorder only had 3 indicator lights but the TNG tricorder has many more. Since it seems ill advised to drive all the leds directly from the 3v3 GPIO pins of the Pi Zero I have decided to have a secondary driver for the LEDs capable of supplying the higher current. In order to facilitate this both the main board and the sensor board will include a 74HC595 shift register to drive the many lights on board. This should do for most of the lights on the picorder, but I am still testing.

I'm going to try and include at the very least:

  • the four green indicator lights (alpha, beta, delta, gamma)
  • the front panel sensor array (the green ripple lights, the various and sundry sensor illuminations)
  • the EMRG button
  • the PWR button.
  • GEO, MET, BIO buttons.

ALPHA BETA GAMMA DELTA

Its always perplexed me that these indicator lights seem to ripple (light up and turn off one after the other) in different directions depending on the season of TNG you're watching.

It makes sense to me that the LEDs on the Tricorder should ripple from top to bottom (ALPHA to DELTA).

I have read (somewhere) that the TNG Tricorder lights were changed by a prop maker to run in the opposite direction only so they could tell when their work was being used on screen.

Power

Umbilical power as supplied by the Raspberry Pi Zero W's onboard USB port.

Portable power is stored by a 1000 mAh Lithium Ion Polymer Battery. Power is then regulated by an Alchemy Power Tiny-UPS. The original Tiny-UPS is hard to find at the moment but I am told a successor is under development and will be available as of mid May 2021.

Gallery

Video Updates

I've been working on some update videos to catalogue my progess.

Media Coverage

I'm delighted that my project has been noticed by some online publications

Raspberry Pi Tricorder: The Next Generation - Ian Evenden, Tom's Hardware
"TR-109 RASPBERRY PICORDER 2 REALLY NAILS THE STAR TREK AESTHETIC" - Lewin Day, Hackaday


This project is a "MyCorder" build and so I'm using this subreddit to solicit advice from the community.