Dontronics Home Page   DT108 SimmStick Video

Sorry, we haven't see the STV5730A OSD video chip for a number of years now, so please don't ask us for them.
We have no alternative.
We do have some blank DT108 boards left, that we are selling at a special price.

18-Nov-2003  5 Channel DT108 project

First a few words about the availability of the STV5730A OSD video chip:

Subject:   RE: Question from Mr. Don McKenzie,
   Date:   Mon, 25 Nov 2002 15:10:25 -0600
   From:   laura.kuosmanen at

thomas.didomenico at wrote:
The STV5730A is being obsoleted. Contact Laura Kuosmanen(laura.kuosmanen at for details.
Best Regards, STMicroelectronics

Hi Laura, can you please give me more details on the STV5730A It is appearing on the shelves of many stockists in plentiful supply again, and as a manufacturer, I have been unable to verify what is going on, as are many of my fellow associates.
we need a definitive answer. thank in advance, Cheers Don...
laura.kuosmanen at wrote:
Hello, The PTN was released on this part and then reversed.  It is not available for new design and will be going obsolete soon. Best regards, Laura

Thanks for the feedback Laura, it there to be a replacement part from ST? Cheers Don...

Hello, I am sorry.   No replacement. Best regards, Laura
Don, On your webpage you have some comments I made last year regarding the STV5730A. You need to update this as we now understand the STV5730A is not about to be obsolete.  Although we have had no official confirmation from ST, it seems freely available from distributors in Europe and the US.
Simon Blake
The BlackBoxCamera Company Ltd.

27-Jul-2001 The STV5730A OSD chip is about to become obsolete:
Information kindly supplied by Simon Blake of The BlackBoxCamera Company Ltd.
We became aware of the situation recently.  We have been advised that November is last orders meaning that delivery can be scheduled into next year for account customers.  We have not decided on a replacement, but there will definitely be no replacement from ST.  See the notice at
As such, when current stocks of the Dontronics DT108 board are sold, there will be no immediate replacement.
Some useful tips on soldering hese surface mount devices.

"Now, video output is as simple as a PRINT statement!"


Construction is fairly straight forward. However, those with limited soldering experience are advised to seek assistance, particularly when it comes to soldering the video chip, which is a surface-mount device. Anti-static precautions should be observed. Once construction is complete, check the PCB for solder bridges before applying power.

Start construction by mounting the video chip. This can be held in place with a drop of glue underneath. Check, double-check, and triple-check that the chip is correctly oriented and lined up with the solder pads before soldering. Once the chip is soldered it will be next to impossible to remove without damaging the PCB or the chip. Use a fine-tip soldering iron, and fine (0.2mm) solder to prevent solder-bridges. If these occur they can be removed with wick or a solder-sucker. The rest of the construction should be done with normal thickness (>1mm) solder.

Next, mount the rest of the components for the main video circuit, shown in RED on the colour-coded overlay. The component values are also shown on the PCB overlay for ease of construction. The resistor marked Rx is not currently used and should not be fitted. Leave the RCA video sockets for last. Note: Although several types of RCA socket will fit on the PCB footprint, the pinouts vary and some will not work. The sockets used in the prototype were obtained from St. Lucia Electronics in Brisbane, Australia. Farnell also appears to have a suitable type (cat# 152-396).

The onboard 5V regulator is only necessary if using the Simmstick video without a powered motherboard. If required, mount the components shown in PURPLE.

Mount the microcontroller components, shown in GREEN, if the serial interface is required. The micro can be an AT89Cx051 or AVR type. It is recommended that the micro is mounted in a socket so it can be removed and reprogrammed, if necessary. Currently the software has only been implemented using BASCOM-8051, although with a little modification it should work with the AVR. Fit the components shown in BLUE if using RS232. Software is currently configured for 9600 baud.


Download Bascom-8051 version of the "simmvid.bas" file in zip format.
Download Bascom-AVR version of the "vidavr.bas" file in zip format. This is the AVR version of the DT108 software for serial to video (9600 baud). The 24MHz crystal needs to be replaced with a 10Mhz one for the AVR, and a AT90S2313-10 is used for the micro.
Download the data sheet for the STV5730A video chip in PDF format.
Download the circuit diagram in PDF format. 


JP1     :   Close if using onboard regulator

*** If fitting links for RX and TX, leave SI and SO open ***

RX, TX  :   Fit links vertically for RX and TX on standard simmbus pins

            Fit links horizontally to reverse RX and TX

*** If fitting links for SI and SO, leave RX and TX open ***

SI, SO  :   Fit links vertically for SI and SO on standard simmbus pins

            Fit links horizontally to reverse SI and SO

*** Leave CLK, CSN and DAT open if using with onboard micro ***

CLK     :   Serial clock signal for OSD chip. Can be connected to D0-D15 as required

CSN     :   Chip select signal for OSD chip.  Can be connected to D0-D15 as required

DAT     :   Serial data signal for OSD chip.  Can be connected to D0-D15 as required

JP6     :   Fit in right-hand position for 89Cx051

        :   Fit in left-hand position for AVR

JP7     :   Leave open (not yet implemented)

JP8     :   Leave open (not yet implemented)

JP9     :   Leave open for PAL, close for NTSC

Part Type   Designator  Footprint   Description 

68nF        C7          RAD-0.2     Capacitor   

220pF       C8          RAD-0.2     Capacitor   

.1uF        C9          RAD-0.1     Capacitor   

33pF        C10         RAD-0.1     Capacitor   

33pF        C11         RAD-0.1     Capacitor

.22uF       C12         RAD-0.2     Capacitor   

.22uF       C13         RAD-0.2     Capacitor   

2.2uF       C14                     Tantalum Capacitor  

75          R5          AXIAL0.4    Resistor    

5k6         R6          AXIAL0.4    Resistor    

2k2         R7          AXIAL0.4    Resistor    

75          R9          AXIAL0.4    Resistor

180         R10         AXIAL0.4    Resistor    

10uH        L1          AXIAL0.4    RF choke

17.734MHz   Y2          XTAL-1      Crystal     (14.31818MHz for NTSC)

PN2222      Q2                      NPN transistor

STV5730A    U2          SOL-28      STV5730A OSD chip   

RCA socket  J1                      RCA PCB mount       

RCA socket  J2                      RCA PCB mount       


.1uF        C4          RAD-0.1     Capacitor   

.1uF        C5          RAD-0.1     Capacitor   

78L05       U3                      78L05 regulator     


33pF        C1          RAD-0.1     Capacitor   

33pF        C2          RAD-0.1     Capacitor   

4.7uF       C3                      Tantalum Capacitor  

.1uF        C6          RAD-0.1     Capacitor   

10k         R1          AXIAL0.4    Resistor    

10k         R2          AXIAL0.4    Resistor    

10k         R3          AXIAL0.4    Resistor    

10k         R4          AXIAL0.4    Resistor    

10k         R11         AXIAL0.4    Resistor    

10k         R12         AXIAL0.4    Resistor    

24MHz       Y1          XTAL-1      Crystal     

BC558       Q1                      PNP transistor      

ATMEL MICRO U1          DIP-20      AT89Cx051 or AVR


1uF         C17                     Tantalum Capacitor  

1uF         C18                     Tantalum Capacitor  

1uF         C15                     Tantalum Capacitor  

1uF         C16                     Tantalum Capacitor  

MAX232      U4          DIP-16      RS-232 transceiver chip

A few additional notes from Lionel 18-Oct-2000
There are a few places where they can be bought: Mouser and Nu Horizons in the USA sell them fairly cheaply but only sell in quantity. Future/Active apparently sell singles, but are much dearer. In Australia you can get the chips in singles from RCS Radio. Dick Smith also sells a kit which contains the chip, so you can probably get it through them as a spare part. I've heard that you can also get them through Braemac, but I haven't comfirmed this.

The other tricky parts are the RCA sockets. Unfortunately there are types which will fit in the footprint, but are the wrong pinout (Don't use the ones Dick Smith sells). The ones I used were from St Lucia Electronics in Brisbane, but looking through the Farnell catalog it looks like they sell a suitable type (cat# 152-396). The middle pin (NOT the outer pins) must be connected to the shield.

It would probably be a good idea to sell a short form kit with the PCB, video chip, and the RCA sockets, as well as a length of .2mm solder for soldering the video chip.

Subject:       Re: Smpte module
       Date:    Tue, 18 Nov 2003 07:26:28 +1100
      From:    Ingmar Meins ingmar_meins at

I thought you might like to share it as yet another working simmstick project. I could not get Lionel's original SSAU2000 project to work no matter what I tried. The decoder was flaky and the software would not even decode a perfectly clean stream of stmpte data from a generator so I rebuilt the decoder and rewrote the software. Works like a charm now. Almost drove me nuts till I put a logic analyser and cro on it to prove it wasn't me !

As for the DT108(s) I increased the timing delays slightly, and they all now start reliably which again they would not do with his software. I have also updated it to automatically reset the video mode if the video mute changes state, i.e. no signal, go to stand alone, signal comes back switch to overlay.

I love this stuff. Thanks again for the point of contact. Maybe there will be more somewhere out there.


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