Matrix Orbital Corp

Being a software guy, I know little about 232TTL -- but I have used straight TTL for simple digital acquisition in the past, on 16-bit DOS computers in which I simply had to read a port value from a known memory address. (Also to write to port addresses to output to a digital LCD module, which is what I'm trying to replace in a 32-bit world with the GTT.)

Can I interface with the GTT via TTL using a (USB) digital acquisition device that provides 5V TTL? There is no discussion of TTL in the protocol manual ...

Hi Ted,

TTL connections are mentioned very briefly in the hardware manual for the GTT480272A.

In TTL mode the GTT will use the same serial communication protocol as RS232, but at 5V/0V logic levels.

Thanks,
~Troy

Thanks Troy ... not much in the hardware manual that sheds light on the subject ... would MO be able to provide any software example or how-to if I needed to go the TTL route?

I do plan on trying the USB route first, if I can run one GTT side-by-side with my DAQ-USB unit, both connected by an unpowered 2-port USB hub that's connected to a powered 5-port USB hub. (My target system would have 5 DAQ-USB units and 5 GTTs -- ten devices connected to one powered USB hub.)

I'm not sure what exactly you mean, the code will be exactly the same, but instead of USB you will be talking to the display Serial TTL.

Hi all,

I see that the module in rs232 ttl mode works with 0-5V
Does is also work with 3.3V signals?

If not, i will choose for a rs232 with a max2323e (3.3V)
Does the following schematic work with the module? or do i need more pins from the db9 socket.

Luc

Hi Luc,

The LPC2468 datasheet for the controller used specifies a minimum input logic high voltage of 2.0V, I expect the GTT will receive 3.3V signal levels correctly. Please note the unit may output levels up to the voltage powering it, make sure your signalling circuitry can handle at least 5V.

Thanks,
Troy