SparkFun Electronics Forum

Hi.
I would like to know if it's possible, and if anyone have tried generating a VGA or PAL signal with the STM32?

Best Regards
Thomas Jespersen

mindthomas wrote:I would like to know if it's possible, and if anyone have tried generating a VGA or PAL signal with the STM32?

I don't know about the STM32 but it has been done on an ARM7 MCU (an LPC2148):

http://en.tieko.nl/?x=entry:entry080822-175419

An alternative (and likely more practical) way to use VGA / SVGA with an MCU is to use something like the Picaso embedded graphics engine via a serial interface.

http://www.sparkfun.com/commerce/produc ... ts_id=8541

There is a baseboard that goes with it:

http://www.sparkfun.com/commerce/produc ... ts_id=8540

The comments associated with the above links are all negative but no details of the alleged problems encountered are given. We haven't tried it ourselves but it looks good on paper and seems worth further investigation. 4D Systems should be able to advise you of any existing problems.

Hi

I have seen several projects using the LPC2148 to generate VGA (up to 480 x 480) - the fairly new BlueBoard (http://www.prlog.org/10325643-low-cost- ... nched.html ) or http://www.pbjtech.com/ have VGA connectors on them to show this.

What I am wondering however is more why? Since the LPC2148 doesn't have any specific HW to support this it seems to be using a timer and toggling ports to get the signals right. Supposedly a high load for the CPU. Supposedly also the same thing can be done with most processors (I also found some AVR references which were doing similar stuff).

Are people doing this just because it can be done or because there are applications behind them? Why not use a chip with integrated LCD controller (like LPC2478 to connect to a high quality TFT?) or much cheaper, a 240 x 320 TFT (about 2" to 3.5") via SPI or external memory interface?

Regards

Mark

mjbcswitzerland wrote:Hi

I have seen several projects using the LPC2148 to generate VGA (up to 480 x 480) - the fairly new BlueBoard (http://www.prlog.org/10325643-low-cost- ... nched.html ) or http://www.pbjtech.com/ have VGA connectors on them to show this.

What I am wondering however is more why? Since the LPC2148 doesn't have any specific HW to support this it seems to be using a timer and toggling ports to get the signals right. Supposedly a high load for the CPU. Supposedly also the same thing can be done with most processors (I also found some AVR references which were doing similar stuff).

Are people doing this just because it can be done or because there are applications behind them? Why not use a chip with integrated LCD controller (like LPC2478 to connect to a high quality TFT?) or much cheaper, a 240 x 320 TFT (about 2" to 3.5") via SPI or external memory interface?

Regards

Mark

Hi.
I have already used a 320x240 display with the STM32, but I would like to show things on a bigger screen (PAL og VGA)
I will check the links you send me and see if I can find anything usefull!

Best Regards
Thomas Jespersen

Should be doable with an STM32 - it has been done on a 32MHz PIC. Lots of detailed info here http://www.micro-examples.com/public/mi ... al-tv.html

rmteo1 wrote:Should be doable with an STM32 - it has been done on a 32MHz PIC. Lots of detailed info here http://www.micro-examples.com/public/mi ... al-tv.html

Yes, I have tried the PIC Pal TV, but it is only Black and White - I would like to do it with colors!

The Parallax Propeller has on-chip VGA and video generation hardware, all you need is a few resistors. It only uses one of the eight cogs (processors), leaving seven for other purposes. An XMOS chip has been used in a similar fashion, with lots of spare processing capacity.

How about display simulator on the PC (using Visual Studio, Visual Basic, etc.)? Send the data out of the STM32 using UART (or UART to USB bridge) and display the output on the PC's monitor. You can use it with any MCU - even an 6-pin PIC. Great for demos and presentations.

leon_heller wrote:The Parallax Propeller has on-chip VGA and video generation hardware, all you need is a few resistors. It only uses one of the eight cogs (processors), leaving seven for other purposes. An XMOS chip has been used in a similar fashion, with lots of spare processing capacity.

Yeah, maybe I should try that.. It is 32-bit too, isn't it?

rmteo1 wrote:How about display simulator on the PC (using Visual Studio, Visual Basic, etc.)? Send the data out of the STM32 using UART (or UART to USB bridge) and display the output on the PC's monitor. You can use it with any MCU - even an 6-pin PIC. Great for demos and presentations.

Hmm, then you HAVE to use a computer. I would like to make the solution independant of a computer!

Yes. They are easy to use, and support via the Parallax forum is very good.

leon_heller wrote:Yes. They are easy to use, and support via the Parallax forum is very good.

Then if I'm going to use the Propeller chip, would you recommend me buying just the chip or a development board?

The Proto board is very good value, and takes a VGA connector. I got one of those, and also designed and made my own PCBs for the DIL and QFP chips.

leon_heller wrote:The Proto board is very good value, and takes a VGA connector. I got one of those, and also designed and made my own PCBs for the DIL and QFP chips.

Which proto board do you have? Do you have a link for a european reseller, and what is the price?

There are two Proto boards, one needs the Prop Plug, the other has it on the board (USB Proto, I think). I've got the former.

You'll find distributors on the Parallax web site. In the UK I can recommend Spinvent, I know Tony who runs it.

mjbcswitzerland wrote:Are people doing this just because it can be done or because there are applications behind them? Why not use a chip with integrated LCD controller (like LPC2478 to connect to a high quality TFT?) or much cheaper, a 240 x 320 TFT (about 2" to 3.5") via SPI or external memory interface?

We wouldn't consider using an LPC2148 to generate the VGA signal but would like to be able to connect a VGA / SVGA display to an LPC2148 (or LPC2106 / LPC2103) board. Main reason being we want to use a large screen (i.e. >= 15") and already have plenty of suitable SVGA displays (both CRTs and LCD).