Max lenght of minipov message

MiniPOV4 and previous versions

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zettaman
 
Posts: 9
Joined: Sun Mar 01, 2009 4:37 pm

Max lenght of minipov message

Post by zettaman »

Hi
What is the maximum lenght of a mini pov message.
Thanks

mtbf0
 
Posts: 1645
Joined: Sat Nov 10, 2007 12:59 am

Re: Max lenght of minipov message

Post by mtbf0 »

the default firmware stores the message in sram, which at 128 bytes is a scarce resource on the attiny2313.

the largeimage.c version of the firmware moves the message data to program memory which is 2048 bytes. so you've got 2048 columns minus the size of the program itself and the program's pretty small.

if you use firmware that has a font built in, depending on how many characters you have defined, you can display text strings of up to around 1000 characters. i wrote a version for use with uv leds that has all 96 printable ascii characters defined that has room for about 950 characters of text. it can be had here, but you'll want to change the initialization code for the timer in order to use it as a regular pov device.

to get a 400hz interrupt frequency use something like this

Code: Select all

//
//  setup timer 0, 1/256 prescale, mode 7, 400Hz, enable interrupt
//
  TCCR0A = (1 << WGM01) | (1 << WGM00);         // select fast pwm w/ top = OCR0A
  TCCR0B = (1 << WGM02) | (1 << CS02);            // and prescale = 256
  OCR0A = 78;                  // gives interrupt freq ca 400Hz
  TIMSK = (1 << TOIE0);         // enable overflow interrupt
  sei ();                       // enable interrupts
there is also code to introduce delays between lines of text, that you might want to adjust. these are controlled by the variables pauseBefore and pauseAfter. you'll need to change their declarations from uint8_t to uint16_t. after changing the interrupt code, as above, a value of 400 in either variable will introduce a delay of 1 second.

why? i don't know. i thought maybe i'd swing a minipov at the end of a very long piece of string, but i never did.

zettaman
 
Posts: 9
Joined: Sun Mar 01, 2009 4:37 pm

Re: Max lenght of minipov message

Post by zettaman »

Thanks for precise answer. :wink:
I will study it.
You speak about a system with uv led. I am about to work with them.
Is there some very important things to know about them or can i use them like "classic" led.
Ciao.

zettaman
 
Posts: 9
Joined: Sun Mar 01, 2009 4:37 pm

Re: Max lenght of minipov message

Post by zettaman »

but i don't really understand what you mean :

Code: Select all

why? i don't know. i thought maybe i'd swing a minipov at the end of a very long piece of string, but i never did.
.
I am not from US/GB.

mtbf0
 
Posts: 1645
Joined: Sat Nov 10, 2007 12:59 am

Re: Max lenght of minipov message

Post by mtbf0 »

zettaman wrote:but i don't really understand what you mean
sorry for not being clear. 900+ characters is a lot of arm swinging with a minipov. what i meant to suggest was that one could tie a few feet of strong string to each corner the minipov and swing it in circles over one's head.

like i said, i didn't try it. mostly due to not having 900 characters worth of wisdom to share with the world and also due to worries about the amount of momentum an accidentally released minipov might have.

zettaman
 
Posts: 9
Joined: Sun Mar 01, 2009 4:37 pm

Re: Max lenght of minipov message

Post by zettaman »

OK i understood.
I won't use large text with my arms...
I'll send you photo if you want!....

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