[Swansea Hackspace] Daily Countdown (but working days not calendar)

[Nathan Hackett]

>From memory I got about 18 hours from 3 AA batteries, with 3x 2.3inch high
led digits. That was at max brightness though, could get a lot more running
them dimmer. Or pick up some £10 10000mah phone charger packs, that would
help. The other downside of larger displays is they can have several leds
in series per segment, which results in a higher voltage-drop than the
arduino can cope with on its own. Things get complicated. LCD might indeed
be more suitable. :)

On Thu, Jan 28, 2016 at 10:43 AM, Ceri Clatworthy <ceri.clatworthy at gmail.com
> wrote:

> [image: Inline image 1][image: Inline image 2]
>
>
> This type of LCD display with backlight off can be vrey low power !!
>
> significantly ledd than a 2" 7 segment LED ??
>
> [image: Inline image 3]    [image: Inline image 4]
>
> does not have to have as meany leds
>
> On Thu, Jan 28, 2016 at 10:16 AM, Richard Morgan <
> richard.morgan at avocation.co.uk> wrote:
>
>> Thanks all.
>>
>> My assumption would be that the bank-hols won't change the much so no
>> need for internet access and likely RTC module for timekeeping.
>>
>> In terms of power-draw - thinking about it the LED display being large
>> would I guess need more than battery power for a prolonged period (could I
>> set it to power down the lights at set times of day/week maybe). I think
>> Raspberry Pi might be overkill but I'm no expert.
>>
>> Not set on what the display is so open to suggestions/guidance - I am a
>> newbie so something straightforward to interface would be helpful for me.
>>
>> Thanks all,
>>
>> Richard
>>
>>
>> On 28 January 2016 at 09:37, Alan Cox <alan at lxorguk.ukuu.org.uk> wrote:
>>
>>> > Ideally it would be something that I could run off a re-chargeable
>>> battery
>>> > pack for portability but plugging in would be okay.
>>> >
>>> > Would this be a Raspberry Pi project or would you recommend an Arduino?
>>> >
>>> > All suggestions very gratefully received...
>>>
>>> I would think pretty much any tiny microcontroller can do it. SPI rtc,
>>> SPI led driver and that's about it. The program ought to be tiny and the
>>> data file you need is 366 bits. Even the lazy man's version is going to
>>> be
>>> under 1KB (table with the correct number to show for each 'day of the
>>> year').
>>>
>>> A PI would be able to run ntp, scrape the government web sites and adjust
>>> if they change the official bank holiday list but does draw somewhat
>>> higher power.
>>>
>>> Alan
>>>
>>
>>
>>
>> --
>> Kind regards,
>>
>> Richard
>>
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>>
>>
>
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