Need Help, MP4 Hardware project

[prelard812]

Hi guys,

I'm an electronic hobbyist and I'm relatively new to MP4 and this world seems very messy at start, to much chipsets and models.

Here is the short story: Do you have a model to suggest me. I need an access to a serial port in order to connect an external uControler who connects a GPS and a Wireless transmission to the player?

Here is the long Story.
I have (I think) a very interesting project. I would like to transform a touchscreen MP4 into a radar system. here is the deal:
Add a GPS and a medium long distance( near 1km) 900MHz link to a MP4. Basically I need a user interface to show menu configuration and position of other persons or objects equipped with the same kind of device. What I need is a compact Big screen and graphic processing to show pre-loaded map. A kind of GPS but who shows other teammates on the map. And yes it need to cheap. IPOD is too expensive. A good exemple is the Garmin RINO-120 page de détails
but more compactwithout FRS because I want to mount the MP4 on my arm to get my hands free. IPOD size is exactly the good format.

So, do you have a model to suggest me. I need a serial port in order to connect my GPS and the Wireless transmission to it..
The UART can be already on an external connector or I can deal with an internal UART on test points, I will rewire it to the outside.
I would like to program the MP4 in linux if it is possibe.

Thank you.

[admin]

Hi prelard,

Interesting topic.
However, from what I know, I haven't seen an MP4 player with a serial port at all. Reading from your post, there is a requirement for the MP4 player to have a serial port, is that right? I'll do some searching around, but I've never seen an MP4 player with a serial port.

When you mentioned about this, I thought about the GP2X which is an open source handheld console run on Linux. However, that also doesn't have a serial port.

Hopefully someone else might know of one, I'll serach and if I find anything, I'll reply.....

[prelard812]

yeah you are right, but GP2x is too expensive for my project...

Linux is not an obligation...

but all chip seems to support at leat one serial port... Some time, manufacturer use serial port as debug feature on the PCB itself.

So a way to go is to open the player and wire up the UART test points for example. But I need to know if people here know a model who has this kind of test point on the PCB for the UART.

Thank you

[pyromaniac303]

Why not just use the screen from one of the mp4 players? It is a fairly simple task to write a display driver for it on a PIC or other cheap microcontroller. For example, the nano clones which you can pick up for about £15 use a PH128128 1.5" CSTN screen, driven by an SSD1779 driver IC. They only have an 8 bit data bus, a couple of other pins and a backlight input.

It already has in built functions like draw shapes, lines etc. All you need is a microcontroller, memory IC loaded with your map images, you can take map images from google earth or somewhere without having to be too complex and use existing GPS software, and correlate it to your GPS signal. If you need communications you can use the UART on the microcontroller.

You really wont get an OS to run on the chip provided with the player(ATJ2085 on mine), it is a dedicated audio player IC with very little capacity to run anything else. If you trawl through the datasheets, you may get your own software running on it. I wouldn't know where to start as information on it is very limited, I can't even find an instruction set summary.

[knob]

This is about the best info I could find:=
http://www.openschemes.com/modules/w...l-port-part-i/

Good Luck!

[lolita]

All the Actions SoCs have UART support.

However, I don't know if 300MIPS DSP and 120MHz Z80 will be enough processing power.

[prelard812]

Thank you guys,

I appreciate your answer. After checking all this, I think I will build my prototype with an old PDA like H3850. Cheap and easy to find. In addition I can target it with linux or WINCE. Full floating point support too.

The idea of a custom uC is on the drawing board too but if theres is no others choice. I would like to get full color display with good looking map. With easy integration. I don't want to rewrite a complete screen driver.

Seriously I will keep you inforrmed when I will get a working prototype

[Th3_uN1Qu3]

You thought well about doing such a project with a PDA. Much less to hack, more time spent developing useful stuff. I know someone who is well versed in firmware mods on PDAs, if you need any help let me know and i'll give you his email address.

[prelard812]

thank you Th3_uN1Qu3, But I will decline your offer becasue things are going well....

I found the basic4ppc compiler who has already a gps integration, serial port and I found a mapping software example on the forum...

Yes, I know, basic is not the most efficient way but it works and is has a fast dev cycle.

I'm currently designing the serial comm between my PDA and the Wireless mcu. My mapping is ready to test with the serial comm when it will be ready

I will post the result in some weeks.