A VGA-type Propeller Backpack thing...
Grogster
Posts: 5
Hi all.
I have just purchased a couple of Propeller Backpack things, to experiment with the TV-OUT ability pre-loaded into these modules. However, I have been reading lots of posts on the forums here, about VGA output, and plenty of photos to prove that the Propeller can certainly generate basic VGA.
Basic colour VGA is all I want - not interested in thousands of colours, 16 or less would be just fine with me.
However, I would need something along the lines of the standard Backpack device, that you can control with serial commands - this might be where the problem is, although the Propeller looks like a very juicy(read: powerful) chip...
I did a search of the forums before posting this thread, and there are plenty of hits for VGA, but they all seem to deal with screen capture of either NTSC or PAL, or VGA output tests in the form of patterns or 8-bit test images etc.
Is there any way to make a VGA backpack type thing - does exactly the same as the Propeller Backpack that outputs NTSC composite video, but instead of composite, outputs VGA instead?
VGA provides a much crisper image then composite does, so the text looks much sharper then composite which tends to look a little blurred around the edges. Not that this is a complaint, just an observation.
I have just purchased a couple of Propeller Backpack things, to experiment with the TV-OUT ability pre-loaded into these modules. However, I have been reading lots of posts on the forums here, about VGA output, and plenty of photos to prove that the Propeller can certainly generate basic VGA.
Basic colour VGA is all I want - not interested in thousands of colours, 16 or less would be just fine with me.
However, I would need something along the lines of the standard Backpack device, that you can control with serial commands - this might be where the problem is, although the Propeller looks like a very juicy(read: powerful) chip...
I did a search of the forums before posting this thread, and there are plenty of hits for VGA, but they all seem to deal with screen capture of either NTSC or PAL, or VGA output tests in the form of patterns or 8-bit test images etc.
Is there any way to make a VGA backpack type thing - does exactly the same as the Propeller Backpack that outputs NTSC composite video, but instead of composite, outputs VGA instead?
VGA provides a much crisper image then composite does, so the text looks much sharper then composite which tends to look a little blurred around the edges. Not that this is a complaint, just an observation.
Comments
You might be interested in this unit then that I developed for a special application, it plugs directly into the VGA socket on the monitor (no cable) and you can run it with a variety of interfaces. Basically there is RS485 or RS422 or direct from RS232. There's also my USB serial module that plugs into it or alternatively my Bluetooth module. Oh, and there is an option for a ZIGBEE module as well, plus an optional switch-mode regulatior and even a USB/PS2 keyboard input. I think that's all. Hang on, there's also TV and audio going to the VGA connector too. I can supply these in any configuration including the head-shell.
...and the inevitable question - how much?
As far as a Backpack-like thing "exactly the same as", it depends on what features you'd want. The Backpack provides audio input and output, video input and output, and video overlaying. Each feature requires some number of I/O pins and a few external components. The daughterboard connector needs a few components to provide possible ADC capability. Some of these capabilities use the same components for different functions since the features are not all expected to be available simultaneously. There are 3 unused I/O pins on the Backpack's Propeller, so it should be easy to do what you want.
I scavenged my DB-15 connector form an old PC display board, but they're readily available from electronics distributors. The pins have a staggered footprint, but it's not difficult to coerce them into the Proto-DB's 0.1" grid. I used a mixture of thru-hole and SMT resistors, since that's what I had; but there's plenty of room on the board for the thru-hole variety. Just use the values recommended in this thread:
-Phil
Forgive me, as I am very new to Propeller...
So, this add-on board obviously plugs into the daughterboard thingy on the main Backback board, by the look of it.
Do I need to load a different program to the one that is in it already, or will this drive VGA directly from the software already in the Backpack from the factory?
I have also ordered a Prop Plug for programming, so that should be easy enough using this plug if need be, but perhaps I don't even need to touch it software wise?
-Phil
I'd need:
VGA
PS/2 Keyboard
Mono Sound output (1/8" jack)
16 I/O pins (P0 to P15 would be ideal)
A small prototype area (like the Propeller demo board, maybe a little bigger)
64KB EEPROM
USB connection (like Propeller demo board)
Bean
Another thing too is I hate bulky connectors and VGA connectors are one of them. I only use them if they really make sense like in the Pixie as it plugs directly into the back of the monitor. When I need VGA then I just plug in a cable to suit. The easiest and cheapest PCB connector to use is a 4x2 pin header with the 5 VGA signals plus 3 grounds.
I'm glad to see you mentioned "mono" sound. What is it with stereo anyway? Most sound is just sound, how can two tiny speakers a few inches apart give us "stereo" sound? It's way overrated and only useful and enjoyable really when it's true hifi and you use headphones.
I normally use a compact 3.5mm stereo socket either wired in mono mode or I feed a TV signal out or sometimes 5V so I can plug in a serial LCD or the like (data instead of TV and 5V instead of audio).
You didn't mention SD memory, wouldn't you need that?
From what I've done so far, I don't think I'd have the program space to support an SD Card. Currently I only have about 4K of program space as it is.
Bean