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But its a current drawn in pulses except for the backlight.
A 1F supercap can deliver 2000mA pulsed current.

So the final current drawn from the battery will be an average of the sums in all the pulsed drains?
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But its a current drawn in pulses except for the backlight.
A 1F supercap can deliver 2000mA pulsed current.

Sure, but you need to fill up that capacitor when you switch it on and replace the electrons after you access the SD card. Have you calculated what that will do to your battery?
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But its a current drawn in pulses except for the backlight.
A 1F supercap can deliver 2000mA pulsed current.

Sure, but you need to fill up that capacitor when you switch it on and replace the electrons after you access the SD card. Have you calculated what that will do to your battery?


It doesnt work that way.

To use extreme figures, if you draw 2000mA from the capacitor with a 1:4 pulsetrain, the load on the battery connected to the capacitor is 500mA constant.

Nothing is disconnected. The capacitor sits parallel to the battery.
The capacitor has a much lower internal resistance than the battery.

Mobile phones do that not to exhaust the small battery with pulsed transmission up to 2watts.
« Last Edit: January 09, 2014, 10:49:43 am by janost » Logged

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Sure, but you need to fill up that capacitor when you switch it on and replace the electrons after you access the SD card. Have you calculated what that will do to your battery?

It doesnt work that way.

To use extreme figures, if you draw 2000mA from the capacitor with a 1:4 pulsetrain, the load on the battery connected to the capacitor is 500mA constant.

Nope, the load on the battery is 500mA *average*. It might be nearly the same thing on a huge capacitor but that leads back to my original question of filling up the capacitor when you switch it on.

Why do you only want one battery?
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Sure, but you need to fill up that capacitor when you switch it on and replace the electrons after you access the SD card. Have you calculated what that will do to your battery?

It doesnt work that way.

To use extreme figures, if you draw 2000mA from the capacitor with a 1:4 pulsetrain, the load on the battery connected to the capacitor is 500mA constant.

Nope, the load on the battery is 500mA *average*. It might be nearly the same thing on a huge capacitor but that leads back to my original question of filling up the capacitor when you switch it on.

Why do you only want one battery?


I never said that I was going to use a single battery?
It was just an idea.

I still have a couple of Li-Ion cells that gives 3.6volt from a single cell.

Only space may constrict the use of 2 batteries.
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I never said that I was going to use a single battery?
It was just an idea.

You said:

I could run it with my own designed voltage booster.
That gives 3.9volts from a single 1.5volt battery.

That sounds to me like you're going to use one battery.


A Quick note: The Adafruit graphics test sketch compiles in just under 16Kb.
Half of the memory in a 328. Not efficient.

Adafruit libraries are many things, but rarely "small".

Code size can be a problem on Arduino. Reasons include:
a) The compiler is very aggressive about inlining (sensible use of "NOINLINE" can reduce code a *lot*)
b) Even though it's an 8-bit machine, all instructions are 16 bits
c) Pushing/popping of multiple registers needs one instruction per register, this can double the size of most functions.
d) Any kind of bit-manipulation code usually gets promoted to 16-bits, even when you're working with bytes.
etc.
« Last Edit: January 09, 2014, 01:35:30 pm by fungus » Logged

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I never said that I was going to use a single battery?
It was just an idea.

You said:

I could run it with my own designed voltage booster.
That gives 3.9volts from a single 1.5volt battery.

That sounds to me like you're going to use one battery.


A Quick note: The Adafruit graphics test sketch compiles in just under 16Kb.
Half of the memory in a 328. Not efficient.

Adafruit libraries are many things, but rarely "small".

Code size can be a problem on Arduino. Reasons include:
a) The compiler is very aggressive about inlining (sensible use of "NOINLINE" can reduce code a *lot*)
b) Even though it's an 8-bit machine, all instructions are 16 bits
c) Pushing/popping of multiple registers needs one instruction per register, this can double the size of most functions.
d) Any kind of bit-manipulation code usually gets promoted to 16-bits, even when you're working with bytes.
etc.


"I could" sounds to me like its an option?
I have done it before but maybe its not enough power for the PlayPad.

I'm only going to use the setup part from the Adafruit library and then push the pixels myself.

It was an info to those wanting to run it on an ATmega328.
It also uses 900bytes of SRAM and the SD library isnt even included.
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I'm only going to use the setup part from the Adafruit library and then push the pixels myself.

I'm busy doing Space Invaders on one of these:

http://www.ebay.com/sch/i.html?_nkw=240x320+tft+lcd+spi

The library was massive but it turns out the chip is really easy to drive So I wrote my own. The entire driver is now only about 200 lines of code (and also draws stuff twice as fast as the 'standard' library).

It was an info to those wanting to run it on an ATmega328.
It also uses 900bytes of SRAM and the SD library isnt even included.

Yep. It uses far too much RAM.
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Nice display.

Is it really 5volt tolerant?

Or just 3.3v IO and 5v supply?
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Nice display.

They're cute. And very cheap...

Is it really 5volt tolerant?

Or just 3.3v IO and 5v supply?

3.3v IO and 5v supply. You need level shifting on the I/O lines

« Last Edit: January 10, 2014, 06:39:32 am by fungus » Logged

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I cant let go of the display you showed me fungus.
What a toy. Definitly my next display in a project.
« Last Edit: January 27, 2014, 12:39:33 pm by janost » Logged

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Quote
I'm busy doing Space Invaders on one of these:
http://www.ebay.com/sch/i.html?_nkw=240x320+tft+lcd+spi
The library was massive but it turns out the chip is really easy to drive So I wrote my own. The entire driver is now only about 200 lines of code (and also draws stuff twice as fast as the 'standard' library).

Looks like a nice display, I ordered 2 from HK for delivery around Valentines Day.... Sure to impress the wife  smiley-mr-green

@fungus, want to share your slim lib?


Ray
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