Today was quite a departure for everyone at Nerd Towers as we all took a trip out into the countryside. It was a grey, damp day, to match our complexions, so there's no chance of any of us being mistaken for cool-surfer-dude-types.

One of the great things about being out in the countryside is nabbing all the freebies from the hedgerows: namely sloes and damsons. They make for lovely sloe gin (the sloes do anyway) and jam (the damsons). We found a quite a few heavily-laden trees and in a few hours stripped all the ripe berries from them (leaving, of course, the unripe ones for future passers-by).
With over 15lb of sloeberries and 10lb of damsons, we're in for a bumper jam-making session these next few days, and need to get hold of about 4 litres of cheap gin! Already there are plans being drawn up for a motorised jam-pan mixer, using three heavy-duty servos and a windscreen-wiper motor from a Ford Mondeo.....

While waiting for the arrival of the lipos from NuElectronics there's not much we can do except, perhaps, the usual thing, which is to jump off and do something else for a while!

A big part of the ScoreSure range will be the online facilites - score "store" (see what we did there) as well as game playback features (where supported). So the ScoreSure website is getting a bit of work done on it over the next few days.

Also, about to start is the new mixed-doubles season at the Brighton and Hove Petanque Club and to coincide with this, the club website has had a spanky new makeover.
The new season starts on 5th September, which might be a little bit early to try out the new ScoreSure Petanque Edition but with a bit of luck, it'll be in regular use before the Autumn sets in and the weather takes a turn for the worst!

Following a discussion on the RobotBrighton Forum, Robot Steve suggested that li-ions are better/safer than li-po batteries. Despite a recent post here extolling the virtues of li-pos, I think he might be onto something: but perhaps not for the reasons he outlined...

After much reading up on li-ion batteries and their variants, it seems that such batteries have a limited shelf-life. Not just a "hanging-around-waiting-to-be-sold" shelf-life (remember, if the battery discharges too much it can become damaged so they need to be used/charged every few months) but also a "use-by" date: typically 18 months - 5 years.
In fact, due to the heavy charge/discharge cycle that laptop batteries go through, many suppliers treat them as consumables now, and I'm thinking along similar lines for the ScoreSure range of devices. So the batteries need to be removeable at some point, not soldered to the PCB via short wires (as was the idea using li-pos).
Because mobile phones are so commonplace, it shouldn't be difficult to get hold of stocks of 3.7v batteries, quite cheaply, in future - and most of these are li-ion, hard-cased batteries, not the lightweight flexible li-pos discussed in recent posts.

When it comes to recharging li-on batteries, eBay is awash with USB phone chargers, for a couple of quid each (less if you buy in bulk) similar to this one.

So while it's going to be interesting to see what turns up in the post over the next few days, there is still plenty of research ongoing, into li-ions as an alternative.

Watch this space....

Dear Nerds,

I am sending two battery packs (including charge circuit & DC-DC step up to 5.5V) to you today, one has 650mAh 3.7V capacity, the other one has 400mAh, 3.7V capacity. These li-poly batteries are the ones I bought for prototype. For my project in production, I will use 1500mAh 3.7V li-poly battery, which is a little bit bigger - 60mm x 50mm x 5mm .

You can plug in USB mini cable to the USB socket to charge the battery from the PC (the LED will turn on). The data lines are available on the USB socket, you need to be a bit careful of soldering wires onto it. For power up your PIC/eeprom, I'd think you better use a proper LDO regulator - like the AMS1117 - step down 5V to 3V3; because the battery outputs anywhere between 3.6V to 4.2V directly.

Regards,
Xing

Any day now, we should have a conclusion to the debate "lipos - good, bad or ugly?"

There has been much discussion about the merits and, worryingly, the dangers of using li-po batteries for providing power for portable devices.
There seems to be some confusion surrounding the safety of "lipo"s versus "lion"s and the general consensus is that lipos are highly volatile, while lions are the "safe" equivalents.

In fact, the opposite appears to be true - lipos are more robust and less likely to be damaged by shock or being dropped (the most likely cause of battery damage in a portable device). Both lipos and lions need careful regulation during charging to avoid overcharging and potentially causing the battery to get hot, burst, or in extreme cases, explode.

It is this fear of explosion that has many people running for cover as soon as lipo batteries are mentioned. Videos exist on the 'net and YouTube showing these types of batteries blowing up apparently due to a tiny variation in charging voltage. This is not really the case: the videos showing battery explosions are (almost) always extreme examples, where the charging voltage/current is deliberately run at a very high rate, to show what is possible if a battery is overcharged.

Lipos have got a bad name for themselves because of these videos - mainly because their flexible outer casing makes them more liable to the spectacular explosion than the lions (which usually are only available in hard cases which are more likely to leak than explode, which doesn't really make for an interesting video on YouTube!)
However, li-pos are built using a later (and it could be argued improved) technology than li-ons. They store more charge for their size/weight and offer improved discharge rates that li-ons. They are popularly used for model aircraft because they are more resistant to damage by shock (for example, an aircraft falling to ground). Yet somehow, they are still seen as the black sheep of the family! Why is this?

Both li-on and li-po batteries can be damaged by under/over voltage.
If the voltage in either a lipo or a lion battery is allowed to fall too low (e.g. below about 3v in a single cell 3.7v battery) then the internals of the battery can be damaged and the battery may not be able to be fully charged in future. Under voltage of the battery does not, however, cause it to explode, leak, catch fire or even get a bit warm.

If the voltage (or charging current) in either li-on and li-po batteries is too great, both can be damaged: the most extreme example being a fire, but the battery has to be seriously abused for this to happen! The maximum voltage is either 4.1v or 4.2v depending on the battery "header" (graphite or coke). Even a voltage difference of 0.1v can cause problems, so care has to be taken....

Should the battery be over-charged, it makes sense that any with a soft, flexible outer case is more likely to swell (and possibly explode) than one with a rigid, hard case. This is where the idea that li-pos are more dangerous that li-ons seems to come from. But given that li-pos are more robust and can cope with being dropped better than li-ons, the li-po battery can be shaped to fit most enclosure designs and provided that the charging circuit can be included in the handheld device (removing the need for the user to handle the battery, to put it into a charger for example) then the case for li-pos seems quite a strong one!

We've a couple on order and in the post, so in a few days, hopefully we can provide an answer based on experience, rather than speculation.....

That sounds crazy, given that the first prototype hasn't even been completed yet (ok, one very early prototype using a 128x64 GLCD has been completed - was it really nearly two months ago? - but the entire product from end-to-end is still in development). Despite this, there are already plans for an entire range of ScoreSure products...

The original idea of a digital score keeping device for boules/petanque remains very much the driving force behind the whole ScoreSure project.
This original idea quickly transformed into a digital scorecard for golf players - incorporating all of the rules for score-keeping in golf, including the some of the less well-known rules such as 4-ball worst ball and Stableford scoring.

After making enquiries with casual players of the game (regular players and golf course staff/owners tend to be familiar with all aspects of the rules) it seems that quite a few players have not had things like Stableford Rules explained fully; with the consequence that a lot of casual players are missing out on playing in the very tournaments that have been designed for them!
For example, Stableford rules allow each player to play and score according to their own handicap and are made up in such a way that one or two bad holes do not blight the score card for an inconsistent player.

The ScoreSure Golf Pro is not just an electronic score card, but also a means of enforcing these rules, so that players can participate in any type of tournament, without the need to keep track of complicated score-keeping rules.

It's a sad fact that, in this day and age, with calculators and computers on every desk and in every pocket, that mental arithmetic is suffering.
A lot of games rely heavily on mental arithmetic, albeit rather simple calculations, for keeping score. Unfortunately, a lot of players are unable or unwilling to keep their own score accurately because of poor arithmetic and/or understanding of the rules of the game.

So this has become the driving force behind a range of ScoreSure score-keeping devices: to take the pressure off the player when keeping scores, no matter how poor their mental arithmetic. The secondary function of the ScoreSure device will be to maintain a historical record of the scores recorded, which can then be stored (online) against a player's profile. Over time, the player will be able to look back over their previous scores and monitor their progress, to see in which areas they need to improve. The ScoreScore method of entering player scores should ensure that entering results:

• is simple to use
• allows easy recall and playback of games played

Games to which these principles can be applied include

• Golf
• Boules/petanque
• Darts

The ScoreSure results website will not only be a repository of players scores, but will enable users to arrange these scores to create and maintain tournament details and league tables.

There are plans for our newest addition to the range - darts - to also include an avatar-based "playback" option online, where each game of darts can be watched, just like a video-playback of a match on the television: complete with split-screen view and character animations! An exciting prospect indeed: but only possible once the first few ScoreSure devices have rolled off the production line!

That's what's needed - by switching to a lipo battery, the entire device footprint can be almost halved! First thoughts were of a 7.4v lipo (double-cell battery) but the Nokia shield has already proved that a simple dc-to-dc step up converter can do the job where supply voltage is lower than the required voltage.

Charging requirements for lipo (or li-ion polymer) batteries are very specific and charging more than one cell can be quite tricky - particularly because of the need to stay within safety limits during charging.

It would probably be much easier/safer to stick to a single 3.7v battery with integrated USB charging circuit, and use this to power the Score Sure range of devices.
From initial investigations, a single battery would be much simpler to work with.
In fact, a recent email from NuElectronics confirms that they are working on developing this very idea themselves, to allow roboteers to power Arduino boards (which require 5v) from a single 3.7v lipo cell.

Charging circuits for single cells are freely available on the net and use relatively simple and inexpensive components.
At the heart of most chargers is the MCP73861 by Microchip.

More details (and schematics) will be posted here as they become available....

As coding for the ScoreSure Golf Pro game score keeping device comes to a close (a few more days testing should see it finished) thoughts are already turning to enclosures and presentation.

The initial idea was to place a PP3 battery (or block of 4xAAA batteries) alongside one edge of the circuit board, effectively placing the screen in the middle of the device (think original Game Boy Advance handhelds). Even with a relatively bulky battery pack, the overall footprint would still be quite small



Maplin stock a handheld enclosure with battery compartment which, on first appearance looks like a perfect fit for the PCB. The only issue is that, in a plain black oblong shaped box, it might look a little "plain".



However, such enclosures also include a recess on the front panel, which is ideally suited to adding your own keypad/graphic. Robot Steve has designed a range of prototypes for the ScoreSure range of devices (each type of device could be housed in a similar enclosure, each with a differing facia).



Even though it's very early days, such designs are very encouraging.
There are still a few decisions which may alter the enclosure requirements (e.g. whether using a 7.4v rechargeable lipo battery and USB charging circuit, in place of AAA rechargeables is a suitable option) but hopfully it won't be too long before we're back to etching circuit boards and making up prototypes to actually try out on the golf course!

Once again, it's been a busy few weeks up in Nerd Towers.
As well as seeing the launch of the usb-multiple servo board via BotBuilder, work continues apace with the ScoreSure Golf Pro game scoring device.

On top of all this an exciting new group has started down here on the sunny south coast - BuildBrighton. It's where a load of like-minded nerdy guys and gals get together and make stuff, using bits and bobs salvaged from all kinds of disused electronic equipment.
Last night was a good meeting - even though a few of the regular faces were missing, there were some really interesting people down there, working on some brilliant ideas. For example, Dangerous Dave was demonstrating his Wii-controlled wheelchair (like Stephen Hawking on speed), Tom spent no time at all ripping up some micro-cameras for his Arduino-based robot, and there was even talk of building a video-enabled weather balloon in the coming weeks!

For the group, I've also put together some videos demonstrating the power and simplicity of ExpressPCB, first covered in an earlier post here. Quite a few members of the BuildBrighton group are quite keen to get their ideas off the breadboard stage and build their own PCBs. ExpressPCB is an excellent tool to use to do just this.

More videos will be posted here as time allows....

It's been an exciting time recently with a few nerdy ideas finally getting to production stage. Which is what the Nerd Club website was originally all about - bringing people together to share ideas, help out with each other's projects, and to get something (finally) finished.

The first such project is the USB-based multiple servo controller board. The prototyping is complete, the hardware (electronics) is finished, the firmware (microchip code) is done and the online flash editor is ready for uploading to its final destination, on the BotBuilder.co.uk website

Here's a photo of the final board in production, complete with silk-printed decals.
The board is available in kit form (solder-it-yourself) and read-to-go, from www.botbuilder.co.uk.

A quick introduction to version 1.0 of Robot Studio.



A flash-based editor (so animations can be stored online and shared) for controlling servos using a 12-channel board with build-in eeprom playback. Add a point by clicking anywhere on the graph. Move points around by dragging. Delete points from anywhere in the graph and it will rebuild to "mend the hole" (for any nerdy-types interested in this kind of thing, it was achieved using a double-linked list, not nasty arrays!)

All points above the centre line mean the servo turns clockwise (at the very top of the graph = full right), and below means turn anti-clockwise (points at the bottom of the graph = full left). Servos can be designated as "angular" (normal motion) or "rotational" (hacked) and the distance of the point from the centreline then controls the speed of the servo.

Because different servos behave differently (one continuous rotation servo may be at dead stop at 50% pwm, whereas another may creep round until at 55%) each servo channel can have its own centre line. All points above this line turn the rotational servo clockwise, all points below turn it anti-clockwise.

The absolute minimum and maximum values for each servo can be set independently. Any points added outside these absolutes are snapped into the acceptable range.

Playback animation and watch the software servos onscreen. Press the export button and you're presented with a stream of bytes. Copy and paste these bytes into the eeprom loader application, and your servo-board is loaded up with data and ready to play back your animation!

The 12-channel servo board is controlled by USB and is recognised as a HID-compliant device (no nasty drivers to install and are even Mac-compatible). The board also supports serial communications, making it compatible with Arduino. The controller boards can be daisy-chained using serial comms, increasing the servo channels from 12 to 24, to 36 etc.

Version 1.0 of Robot Studio supports a single board.
Multi-board support is being developed for v2.0

The controller boards are available to buy at http://www.botbuilder.co.uk/store

After a few problems at the RobotBrighton Demo (the least of which was not being able to get the board to work properly!) things were looking bleak for the multiple USB servo controller.

It didn't matter what sequence of bytes the online editor spat out, they could never be sent (and read back) from eeprom consistently.
Sometimes bytes were missing, sometimes byte values were changed for others, and sometimes, the bytes read back looked nothing like those that were supposedly written to the device!

It turns out that the problem was a timing issue, between the MCU and the eeprom.
You see, the processor is running at 20Mhz, whereas the eeprom can only manage a measly 400khz (yes, khz) at best. This obviously leads to timing issues, particularly when writing to eeprom.

Finding the exact cause of the problem was a nightmare, particularly with a demo that was running late (and looking quite likely to not happen at all). Luckily, the problem was easily resolved by added a 5ms delay after writing each 4-byte chunk to memory. So now the board works just fine.

Which is just as well, otherwise it would mean that this last week would have been wasted, as most of it has been spent perfecting the Flash-based servo editor interface



This spanky editor allows you to control up to twelve separate servos using a simple click-n-drag interface. It uses a double-linked list to keep track of each of the graph points, allowing them to be dragged around and their position within the horizontal timeline to be altered quickly and easily. As each point of the graph is dropped into its new location, the graph is redrawn quickly without the need for popping and pushing array elements around the place. Linked lists are perfect for when you need an array of items that could regularly change place within a list.