VK202-25: Direct TTL communication

Mathieu_R · Post by **Mathieu_R** » Sun Aug 29, 2004 11:25 am

Dear All,
I'm using a micro-controller (TTL levels) to write on my VFD display.
Is there a way to directly wire the TTL signal to the display without performing a TTL->RS232 conversion before ?

I can see that the DB9 plug on the display is connected to a SP232 chip that performs the RS232->TTL conversion but I can't find where the TTL signal is available to solder a wire.

Thanks

Mathieu_R · Post by **Mathieu_R** » Sun Aug 29, 2004 12:05 pm

When looking at the PCB board, above the SP232AEN chip, I can see 2x4 solder pads. See picture.
Can I solder the column 2 and 4 and unsolder columns 1 and 3 to bypass the RS232->TTL converter with no danger ?

Tom · Post by **Tom** » Mon Aug 30, 2004 8:51 am

If you solder 2 and 4, and desolder 1 and 3, you will get what you desire. It will bypass the RS-232 with safety.

Mathieu_R · Post by **Mathieu_R** » Mon Aug 30, 2004 1:17 pm

Thank you. I did it and it works correctly.
I also soldered an other pad to supply 5V through the DB9 plug. The user manual indicates we can do this but it was not working.

Tom · Post by **Tom** » Mon Aug 30, 2004 2:03 pm

Do you have a 5V or a 12V display? If you have a 12V module, you need to power up the display at the DB9 connector with 12V. It will have a 3 terminal 78M05 regulator, if it was a 12V module.

Mathieu_R · Post by **Mathieu_R** » Mon Aug 30, 2004 2:33 pm

I have a 5V display.
The pad I soldered is located in the bottom left corner of the DB9 when looking at it.

Miles · Post by **Miles** » Mon Aug 30, 2004 4:56 pm

What type of power source are you using when your trying to power up the module via the DB9...?

How is it connected?