Thursday, 19 February 2015

Nintendo DSi - Resetting Parental Control

The Problem

If you've ever watched kids use computer devices then you'll be aware of their preoccupation with the menus (or screwing around with the settings). I've gotta admit the worst incident of this was when I had to reset the language on an MP3 player from Chinese back to English.

Anyway my son (let's call him Dick to retain his anonymity) has wasted countless hours exploring all of the menu options and settings on his Nintendo DSi. At some stage we think he set the parental lock and then forgot the four digit code.

He'd been complaining for some time about how we need to ring up Nintendo's Technical Support and get a reset key. And we've done our best to ignore the request, keen to show him that there's a real world impact to "buggering about with things in a hap-hazard way".

The net result of this problem: he can't access the web (fine by me), and can't access the Nintendo Shop (again fine). The latter generally forces a firmware update, which in the past has stopped their R4 cartridge from working.

But after replacing his brother Harry's DSi at the weekend, Dick became very upset that the new machine had DSiWare on it that his didn't have. Specifically Flipnote Studio!

Flipnote Studio - Finally a constructive use for the DS

He initially tried to copy the app over using an SD card, but it refused to copy back to his DSi. (Nice try but it's restricted to that console during the download. Copying to an SD card should be viewed as a backup only.)

I think it's a pretty good program, so I waited until they were in bed and then attempted to access the Nintendo Store.

Parentally Locked

My first problem was unlocking internet access. The old four digit code (we'd set when the DSi had belonged to Tom) wouldn't work, so I was then asked to enter the town were I was born. I tapped it in but - no go!,  then tried my wife's - also no! (and various other places we'd lived - all to no avail)

Eventually I was presented with an eight digit enquiry number and advised to contact Customer Support to obtain a master key. I fired off an email, but in the mean time carried on looking for an alternative.

I got a standard reply from Nintendo stating they were busy and would respond soon, and then I found the following page..

Obviously it's meant for the Nintendo Wii, but it also works for the DSi.

Enter your enquiry number and click on the button to receive your 5 digit master key.

If it doesn't work check the date is set in-correctly on your DS.

Tuesday, 10 February 2015

Raspberry Pi Diary - Scratch GPIO and 7 Segment Displays

Installing Scratch GPIO

The standard version of scratch can't control the GPIO, so you need to install ScratchGPIO7 before you can play with LED's and switches. I googled the install instructions but here they are if you need them:-

wget -O

sudo bash

If you need to add the desktop icons to other users you can specify user name on that last command:-

sudo bash fred

(nb. make sure you have an internet connection first!)

Use the new desktop icons to start scratch and it will ensure a background python task is running that enables the GPIO control.

There's a simple code example that toggles pin 11 between low and high. We attached an LED to this pin, (using a 470R resistor) and connected the other end to one of the ground pins. (doesn't matter which)

Success - a flashing LED!

Moving on from Basics

The plan was that I'd set my 8 year old a task of driving one of his 7 segment displays using the Raspberry Pi, and maybe get it counting 0 to 9.

It seemed like a suitable jump of of complexity both in software and breadboard wiring. (perhaps it was a jump too far) Here's what happened!

Circuit Debugging

My son disappeared for half an hour and returned with breadboard, 7 segment display, and T-Cobbler carefully connected with jumper wires. He plugged it in to the RPi, loaded up the pin 11 demo program and clicked the green flag icon to run the program. The scratch variable was clearly cycling on and off on the screen, but none of the segments lit. We ended up tearing the circuit down trying to get it to work and along the way discovered a few problems..

1. The T-Cobbler board has 40 pins that need to be inserted into the breadboard. That takes more insertion force than you'd think.

2. The LED display was of the common anode variety. This means that all the anodes are connected together and the segments lit by pulling the individual cathodes down to ground.

(So he had connected the LED segments the wrong way round.)

A quick flick through the Maplin catalog confirmed you can get common cathode versions.

Driving Common Anode Displays

My initial thought was we'd have to use a transistor inverter to drive each segment, but that's a fair bit of extra complexity and not strictly necessary.

A simple inverter circuit is not necessary.

Each GPIO output actively pulls high or low, so if you connect the common anode to 3.3v then any low pins connected to the cathodes will turn the display segment on.

Connecting a common anode display to a Raspberry Pi

The only hitch is the logic is the other way around! (pin low = segment on)

But it's only just occurred to me that we could do this after reading the Raspberry Pi GPIO Documentation and seeing an LED connected this way. (Must try this tonight!!)

Wednesday, 4 February 2015

Raspberry Pi Diary - Breakout Boards

Interfacing 101

One of the main reasons why I bought the Raspberry Pi was to bring together the two worlds of electronics and computing for my two youngest sons. The oldest of the two already has various components and breadboard to play about with, and he's already been experimenting with scratch for a while now.

The great thing about the Raspberry Pi is that it has those GPIO pins just waiting to connected to LEDs, switches, sensors or the wide variety of add-ons that you can buy these days. I thought I'd start by getting a simple breakout board from Maplin.

GPIO Breakout Board
I got one, but lets just say I made a few mistakes!

Mistake #1

It comes in kit form, requiring the ribbon socket and header pins to be soldered together before you can use it. There's a simple diagram that suggests how the ribbon connector should connect to the GPIO pins and which way it should fasten into the breakout board. Seemed simple enough but it wasn't obvious which way up the board should go.

One end of the breakout board
One end was labelled 'GPIO HEADER' (see diagram), so I concluded that it belongs this way up and started soldering the socket. After I'd done about eight I started to get the niggling feeling that it wasn't correct. I stopped and traced the wiring only to find I actually had the board upside down!!!

Now unsoldering a double-sided board is a nightmare, and my desoldering pump just wasn't doing the job. In the end, I levered the socket away from the board leaving the soldered pins still attached. These were then individually removed with a hot soldering iron and a pair of pliers.

Botched breakout board with removed socket pins.
Now I'll have to drill out the remaining solder before I can start again. (This wasn't going well!)

Mistake #2

It wasn't until my son came through to check how I was getting on that I realised my next mistake. I was explaining to him about how the ribbon plug would fit into the GPIO. When I went to demonstrate this I spotted my next mistake. (this one pretty fatal)

This was a 26 pin breakout board for the original Raspberry Pi, but I'd bought the newer RPi B+ model, which has a 40 pin GPIO. The ribbon plug won't fit and if you try to force it you'll end up bending some of the pins. (darn!)

Let's do it Right

All I can say is "Cobblers" - or to be more exact Adafruit's T-Cobbler Plus. As soon as I opened the bag I was immediately impressed by the improved quality and the neat screen printing showing (without doubt) which way the socket should be soldered.

You can bet I still checked it carefully before I started, but within about 10 minutes it was done.

The assembled Adafruit T-Cobbler Plus
My son quickly relieved me of it and started building a circuit to light his 7 segment LED display.

(More about that another day)

Oracle APEX - Advanced Tabular Form Validation


In my previous APEX post I took you through a method of adding click-able column help to your tabular forms. I also needed to add validation between my columns, and initially it wasn't clear how I might do this. You can validate against static values, normal item values, or just check for nulls, but nowhere can you validate against a value from another column on the same row.

Tabular Form Requirement

Just to recap from before, I have a table of measures with three columns to hold the weighting, cap and uplift values for each. (shown below)

My Tabular Form
The validation I wanted to add was to ensure that if a Cap value is added then it must be greater than the Weighting value.

One way of performing this type of validation is to use some jQuery code which runs on the browser, but generally its not recommended for security reasons. Instead we'll use a method that replies on the inherent use of collections for tabular tables and write our validation using PL/SQL.

Creating the Validation

1. Run the page containing your tabular form and inspect the input fields from the columns your need to validate to get their id's.

The HTML for the first Weighting field is:-
<input id="f03_0001" type="text" value="0" maxlength="2000" size="2" name="f03"

The HTML for the first Cap field is:-
<input id="f04_0001" type="text" value="0" maxlength="2000" size="2" name="f04"

So the two pieces of information we need here is f03 and f04.

2. Create a page level validation and give it a suitable name. (I'm going to call mine "Check Cap Values Exceed Weighting")

3. Select 'PL/SQL' as the validation type.

4. Then select 'Function Returning Boolean'.

5. Here's the code I entered:-

  FOR i in 1..apex_application.g_f03.count
  IF apex_application.g_f04(i) IS NOT NULL
    THEN IF apex_application.g_f03(i) IS NOT NULL 
      THEN IF TO_NUMBER(apex_application.g_f04(i)) <= TO_NUMBER(apex_application.g_f03(i))
        THEN RETURN false;
      END IF; 
    END IF; 
  END IF; 

NB. APEX automatically creates a collection for each column in a tabular form ("apex_application.g_f01", "apex_application.g_f02" etc...) This function loops through the values in columns 3 and 4 comparing the values. 

It's reasonably simple, just don't forget to turn these values into numbers before you do your comparison, or you'll find that 8 is greater than 10 and your validation won't work as you intended!

6. Enter the following for Error Message:-

Cap values must be greater than Weighting, or left empty.

7. Finally set the condition to When Button Pressed 'SUBMIT'.

That's it!