Building the logger

These instructions are for Prototype E

Proto E is not the latest design: we recommend building Prototype F.

Prepare the MicroSD card

• Connect the MicroSD card to your computer and format it in FAT32.
• Create a folder named ‘config’ in the card’s root directory.
• Download the config file here and place it in the config directory.
• Open the config file in a text editor and add some wifi credentials.
• Eject the MicroSD card. Install it in the MicroSD slot in the underside of the dev board.

Build the logger

Now the fun really begins. Check that you have all the things shown in the picture.

Solder headers to PCB and dev board

Soldering

It is assumed that you have basic soldering skills. If not, there are many online resources - it’s not particularly difficult and having some familiarity will greatly increase your success rate at building the logger.

The dev board is installed in the PCB with a removeable pin/socket arrangement. This allows the dev board to be easily removed for re-use in later PCB revisions.

Cut two sections of pin header, one with 12 pins and one with 16, for soldering into the dev board.

Install the pin headers. Insert the short sides of the pin headers into the underside of the dev board (the side with no connectors). Solder one pin on each pin header to the dev board.

Check the pin header alignment. The pin headers should be square to the board. If necessary, gently bend the header around the soldered pin. Solder the rest of the pins.

Note

Use a breadboard if you have one

If you have a prototying breadboard, installing the headers in the breadboard for soldering will guarantee squareness.

Cut two sections of pin socket, one with 12 holes and one with 16, for soldering into the PCB. Take care: unlike pin headers, these are not really made to be cut to length. Cut through the next hole rather than between the holes.

Insert the pin sockets into the PCB. Insert the pin headers on the dev board into the sockets to keep the sockets square and parallel while you solder them.

Solder the pin sockets to the PCB. Turn the assembly over and solder the pin sockets to the PCB from the underside.

Install navigation pin headers. Cut a section of pin header 6 pins long and solder it into the PCB in the holes labelled ‘navigation’.

Solder QWIIC cable to OLED display

Cut the QWIIC cable, leaving approx 100mm of cable on the connector. Strip approx 4mm from the end of each wire.

Prepare the OLED display. If your OLED display has pin headers installed, carefully pry off the plastic collar at the base of the pin headers with a craft knife and cut the headers to around half their original length. Cut 4 sections of heat shrink, approx 6mm long and thread one onto each wire of the QWIIC cable. If the display has no pin headers installed, no action is needed.

Tin the ends of the wires and solder them to the pin headers or into the connector holes as applicable. Take care to solder the wires in the correct positions. Slide the heat shrink pieces down over the pin headers (if applicable) and apply heat.

Take care with the OLED display

The OLED display is fragile. Handle it with care so as not to crack it. If your OLED display has pin headers installed, do not attempt to de-solder them. It is easy to damage the copper traces when doing do.

Connect the keypad and screen and check the build so far

Connect the keypad and display. Plug the QWIIC connector into the dev board. Connect the membrane keypad to the navigation headers on the PCB, ensuring the connector orientation matches the picture.

Connect the dev board to a power supply with a USB cable. Press the ‘RST’ button on the board. The OLED display should now show the home screen Check keypad operation. Pressing the right arrow should enter the menu system. Pressing the ‘Sel’ key from the home screen should toggle logging on and off.

Assembling the connectors

Fiddly work ahead

This is a fiddly job and it is worth getting organised to do it properly. There is limited room inside the case for excess wire so using the recommended wire lengths is important. Using the suggested wire colors will make your life easier too.

In this step you will be wiring the connectors to the PCB. The guide covers the standard connector configuration: 4 analog inputs, one I2C input and one connector for a handlebar-mounted switch. Other configurations are possible: the minimum useful configuration would be 2 analog inputs.

The UART and I2C1 connections

In addition to analog and I2C0, the PCB breaks out a UART connection and an additional I2C bus. The I2C connection is not currently in use but in future could be used to connect a GPS module. The second I2C bus may be useful for avoiding I2C address conflicts. (For example, the popular AS5600 magnetic rotary encoder has the same I2C address as the dev board’s on-board battery monitor, so any AS5600 sensors will need to be on the second I2C bus, or use an address translator IC).

Install the connectors in the 3d printed end pieces and tighten. Ensure that the connector o-rings are on the outside and sit in the chamfered edges of the holes. Place the connector assemblies face-down. If possible, secure them in a vise. ‘Tin’ the pins on the back of each connector with a small amount of solder

Prepare the hookup wires. Cut and strip short sections of hookup wire for each connector in the recommended lengths. Note the lengths are for the insulated portion of the wire. Allow some extra to strip the ends. Strip approximately 3-4mm from the ends of the wires and tin them with solder. Work quickly as too much heat will damage the wires’ insulation.

Connector	Pin	Cable length	Color
Analog 0	All	22 mm	Vcc=Red
Analog 1	All	12 mm	Gnd=Black
Analog 2	All	25 mm	Signal=Green
Analog 3	All	22 mm

Connector	Pin	Cable length	Color
Switch	LED	20 mm	Green
	Mark	20 mm	Yellow
	Gnd	20 mm	Black
I2C	Gnd	17 mm	Black
	3.3V	17 mm	Red
	SCL	17 mm	Yellow
	SDA	17 mm	Blue

Solder the wires to the connectors. This is much easier if the connector pins and wire ends are tinned first. Use the soldering iron to heat the pin until the solder melts. Insert the wire end into the molten solder and withdraw the heat. Repeat for all wires. Check that all the wires are secure and excess solder is not present.

Apply heat shrink. Cut short sections (approx 6mm long) of 2.5mm heat shrink and pass one over each wire down to the soldered connector joint. When all are in place, apply heat to activate the heat shrink.

Solder the connectors to the PCB. Solder the free ends of the wires into the PCB so they enter the PCB from the top. Take care to ensure the wires are connected correctly as per the picture. Trim any excess wire sticking through the bottom of the board.

Caution

Handle with care

Handle the assembly with care. The wires are fragile and vulnerable to damage until the PCB and connectors are mounted in the case.

Prepare the case

Remove support material from the case using a craft knife. If printed in the recommended orientation, the majority of support material will be for the shallow indent where the keypad sits. Make sure the material is thoroughly removed. The cosmetic appearance is not important since the keypad covers it, but it should be as flat as possible.

Optional: Install heat-set inserts. If you are using brass inserts rather than nuts to close your case, they should be installed now. Install them straight and flush using a soldering iron.

Install the components

Install the PCB and connectors. Place the PCB into the lower half of the case, ensuring the right-hand edge is captured in the slot designed for it (the left-hand edge is held down by the upper half of the case).

Position the case end pieces into their slots and ensure all the wiring sits cleanly.

Take your time

Getting the PCB to sit flat may require some careful manoeuvring of the wires. Take your time and don’t force anything.

Install the battery. The battery sits in the slot on the right-hand side of the case with the wires facing to the front of the case. If necessary trim or extend the battery wires. The recommended wire length is 70 mm.

Caution

Check the battery polarity again

Route the battery wires as shown and connect to the JST connector on the dev board.

Assemble the keypad and display. Gently remove the plastic shell from the end of the keypad’s ribbon connector by gently prying up the front edges of the locking tabs with a craft knife. Pass the ribbon connector through the hole in the front of the case and re-install the plastic connector shell.

Peel off the self-adhesive backing from the keypad and press it firmly down to the case.

Tuck the lower edge of the oled display into the slot at the bottom of the opening. Press firmly on the top corners of the display to lock it in place.

Caution

Press only on the corners to avoid damaging the display.

Connect up and close

Connect the keypad and display. Connect the loose ends of the QWIIC cable to the OLED display. Connect the other end to the QWIIC connector on the dev board.

Connect the keypad connector the the navigation pins.

Carefully close the case. Take special care with the keypad ribbon connector. It can be bent, but minimise this if possible.

Secure the case with 4 M3x12 cap screws and tighten.

Congratulations!

Well done. Take the rest of the day off.

Optional but recommended: waterproofing

The water-resistance of the logger can be dramatically improved with the judicious application of caulking silicone at selected points:

• Seal the keypad ribbon connector where it passes through the case from the back.
• Cut a 16mm x 28mm piece of clear plastic (an old visor is ideal) and silicone it into the recess in front of the OLED display.
• Partially fill the gasket groove in the top half of the case with silicone. Carefully apply silicone to the groove (you can do this with a small syringe) and then form it to shape with this 3d-printed spatula tool.