Using the LCD

I found an old beaten-up CD player a while back, and decided to take out the human interface card, with the LCD and buttons on it.

In a previous episode, I managed to get the LCD to do something. Now, I will try to let it do exactly what I want it to do!

The first task is to find out what segments is controlled by what segment to the chip(s). In Controlling the card, I found out how to send the chips data — basically I have to send an 80-bit sequence to the two chips, of which 2*4 bits are chip control data. This leaves 72 bits of data to control 57 segments, so some of the chip’s capacity was unused.

My first plan of attack is simple: in the previous episode I learnt how to listen for keypresses, so my idea was to make a simple keypress-driven loop trough all the 72 data bits, to see which segment will light up.

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Scanning keys

Now that I deciphered where everything goes and how everything works, it was time to make sure I build a foundation to make the I/O a little more usable, instead of fetching raw data. Fist stop: make the input buttons accessible.

Working with keypresses is actually not as simple as I intuitively thought. If you have one button attached to one input pin and do a simple digitalRead(pin);, then you know your button is pressed. But if you want to do an action only once on every key press? You could have a little variable that keeps track of whether the key was not pressed last time and is now — basically working on the leading edge. But then you still have the problem of key bounce to take care of.

And what if you want to detect long presses (e.g. to go into a settings menu) or held presses (press once to increase a counter, keep pressing to keep increasing it)?

But first, the basics, how to detect a simple keypress with the scan matrix used in this board?

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Controlling the card

I found an old beaten-up CD player a while back, and decided to take out the human interface card, with the LCD and buttons on it.

In a previous post, I found out where all the connections on the PCB go and how they connect the buttons, LCD and chips together and what they do. Now, I will try to see whether I can control them.

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Interfacing with a human interface card

I found an old beaten-up CD player (a Philips AK601) next to the trash container a while back.
I picked it up, found it not worthy of being taken back into use, so I decided to open it up and maybe gut it for parts. I found a couple of motors inside, but what really drew my interest was the human interface card, or the print which holds the buttons and LCD.

The card is a one-sided PCB, with on the backside (the green side which holds the traces) three ICs, and on the other side an LCD screen (with what seems to be two incandescent lightbulbs as backlight, 8 diodes, 13 buttons, one capacitor, one transistor, a 9-strand ribbon cable that connects to the motherboard and a hell of a lot (25ish) wire links.

The LCD is an interesting one: it has 6 7-segment digits and a few more items, like whole-word PAUSE, SHUFFLE etc, separate digits 1-6 (presumably for a cd changer) and two “cd” icons.

Enhanced picture of the LCD segments. Dirt also enhanced.

My curiosity was triggered by how simple everything looked and I started on a quest to understand this board.

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Track plan sites

Sporenplan.nl — Track maps of the trains Netherlands, and partially of Belgium, Germany and other countries, and tram & metro of the Netherlands

Cartometro.com (formerly carto.metro.free.fr) — Track maps of most French city rail (metro & tram) systems and a few abroead, among which London

Urbanrail.net — Network maps of most urban rail systems in the world

Gleisplanweb.eu — Track maps of most of European’s urban (tram & metro) networks

Railway Codes — Track maps of some of the UK’s tram systems

A Complete and Geographically Accurate NYC Subway Track Map — The NYC subway including Manhattan and Bronx’ LIRR, PRR and other railroads

Binders for cables — Bindstripjes voor snoeren

As any tinkerer, I have a lot of cables — power cords, USB cords, network cables and the like. I litterally have 5 drawers full of them. The problem is getting the cords to not coil up.

Zoals iedere knutselaar heb ik een heleboel snoeren — stroomkabels, USB-snoertjes, netwerkkabels etcetera. Ik heb letterlijk 5 laden vol snoeren.

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Restoring a template / een sjabloon restaureren

The ship I sailed on a lot, the Ebenhaëzer, is a so-called klipperaak — a ship with the front of a clipper and the rear of an aak.
The front of a clipper — sometimes — has klipper curls [examples], which is a painted floral ornament, symmetrical on both sides

Het schip waar ik veel op gevaren heb, de Ebenhaëzer, is een klipperaak, wat altijd uitgelegd is als “een schip met een klipperkop en een akenkont”.
Op de voorsteven van een klipper zitten — soms — klipperkrullen [voorbeelden], ofwel een geschilderd lofwerk, symmetrisch aan beide kanten.

The Ebenhaëzer has clipper curls. [Kasper] wanted to build a chest and paint it Ebenhaëzer-style, so needed a template.
Fortunately, the ship’s paperwork binder has a template, used when the head of the ship is re-painted.

Ook de Ebenhaëzer heeft klipperkrullen. [Kasper] wilde een kist maken en vervolgens schrilderen in Ebenhaëzer-stijl, en had dus een klipperkrullen-sjabloon nodig. Gelukkig zit er in het motorboek van de Ebenhaëzer een sjabloon, voor als de kop geschilderd moet worden.

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GR 412 Sentier des Terrils E1: Eijsden — Blegny — Micheroux

I decided to walk the GR412 – Sentier des Terrils — a walk along the coal mining axis — and thus spoil tip (Terril) axis of Wallonia. The GR runs from Blegny, close to Maastricht, to Bernissart, on the French border.

Ik heb besloten de GR412 – Sentier des Terrils te lopen — een wandeling langs de kolenwinningsas — en dus steenberg-as van Wallonië. De GR loopt van Blegny, bij Maastricht, naar Bernissart, dicht bij de Franse grens.

Red: my route. Blue: GR412
Rood: mijn route. Blauw: GR412
Stage / Etappe : 1
Date  / Datum  : 14-12-2019
From  / van    : Eijsden (NL) (57m)
To    / naar   : Micheroux (277m)
Km             : 30.79km
Time           : 7h03m
Terrils        : 2 (0 climbed / beklommen)
Weather        : First sunny, then cloudy, 11°C, occasional rainshowers
      / weer   : Eerst zonnig, later bewolkt, 11°C, af en toe regenbuien
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GR 412: Terrils visited

I am walking the GR 412 – Sentier des Terrils.
There are a lot of terrils (slag heaps) in Belgium, about 740 in Wallonia alone, mostly lying on the Liege ­— Charleroi — Mons — Lille axis. The GR 412 follows this axis.

Below is a list of terrils my walk put me on, or directly next to. There are many more I have seen.

The list will be updated as my walk progresses.

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