Demo Board - Video - Clock - Low Power

Humanoido

The goal is to run the Demo Board for minimum power draw using the internal slow RC Clock/Oscillator circuit, and at the same time, run FemtoBasic and view the composite video on TV input.

There are two questions. 1) will the video continue to work? 2) What is the code to do this?

I think the following code is correct. It there any other syntax to add or change?

CON
_CLKMODE = RCSLOW

Thanks.
Humanoido

MagIO2

From TV.spin:

'' bit 0 selects NTSC or PAL format
'' 0: NTSC
'' 3016 horizontal display ticks
'' 243 or 486 (interlaced) vertical display lines
'' CLKFREQ must be at least 14_318_180 (4 * 3_579_545 Hz)*
'' 1: PAL
'' 3692 horizontal display ticks
'' 286 or 572 (interlaced) vertical display lines
'' CLKFREQ must be at least 17_734_472 (4 * 4_433_618 Hz)*
''

Phil Pilgrim (PhiPi)

Even if an RC clock were fast enough, it would be neither accurate enough nor stable enough to produce a usable video signal. So the short answer to question 1) is "no".

-Phil

Humanoido

Thanks much Phil & MagIO2. With RC clock values, it looks like video is out, however some alternatives exist such as LED signaling, sensor and sound debugging, and LCD message displays. There is a uoled FemtoBASIC version. I hope there are no clock restrictions on this. I don't know if an LCD FemtoBASIC version exists. Any ideas?

humanoido

Post Edited (humanoido) : 11/20/2009 3:07:35 PM GMT

MagIO2

Yep ... LCD works. I mean the ones with their own text- or frame-memory. The timing there usually has no limit in slow direction - there's only a limit in how fast you can send.
I'd expect that the best you can get for low speed is black'n'white graphics (128x64) - of course without animation ;o). High res or high color will work, but will be no fun.

If you only want to display text, then get a display with up to 40x4 characters. Before I started with a high res high color display driver, I worked on a driver for such kind of displays. In the end it should be possible to let the driver do automatic scrolling of single lines. This way even 16x2 displays could show plenty of information. As it's written in PASM the low clock-frequency should not be a problem.