Sychronous Serial Interface on Newhaven M0220MD

pipperoni · Post by **pipperoni** » March 11th, 2008, 5:07 am

Hi LCD Smarties,

I just bought the Newhaven M0220MD-202MDAR1-3 VFD because it is dirt cheap, especially for 9mm characters.

Unfortunately I don't have a parallel port so I was hoping that I could use the "Sychronous Serial Interface" on the VFD if that means I can use it with a serial port (check the product link for the spec). The trouble is, I don't know if they are the same thing. So two questions:

(1) Is "Sychronous Serial Interface" compatible with a standard 9 pin serial port?
(2) If so, what are the corresponding pins on the serial port to the "SI/SO", "STB" and "SCK" on the VFD?

The more I look at it the more I'm afraid I'm building a USB to Parallel port adapter...

Thanks!

grantb3 · Post by **grantb3** » March 11th, 2008, 4:42 pm

Code: Select all

SI/SO - Serial in/out
STB   - Strobe (enable)
SCK   - Serial clock

The protocol looks almost like I2C, but in any event it's not going to work with an RS-232 port without some kind of bridge chip/board. Same with USB.

Does nobody make a USB to parallel LCD chip (supported with a DLL for LCD Smartie)? I know there are lots of RS232 ones (E.g. ede702).

http://forums.bit-tech.net/showthread.php?t=115461
http://www.harbaum.org/till/lcd2usb/index.shtml
http://idyllicinc.com/xcart/product.php ... t=1&page=1

pipperoni · Post by **pipperoni** » March 13th, 2008, 1:11 am

Thanks for the info, I've been looking at the FTDI chip to do USB->Parallel, but the EDE702 might also be a good way to go.

By way of CPU cycles, does it cost more to go USB or serial? Or is CPU usage so low in general that its not worth thinking about?

grantb3 · Post by **grantb3** » March 13th, 2008, 5:00 am

Serial (RS232 or virtual over USB) will be more stable in my opinion.

Post by **caesar** » March 15th, 2008, 10:44 am

In terms of CPU cycles serial and USB consume much less than direct parallel port, because the burden and timings to drive the lcd are taken away from the host computer to the small microcontroller on the display board.

If you use the winamp plugin and set refresh rate to 11ms then you'll see the cpu usage arond 10-15% depending on your cpu, but using serial or better USB (not the case with FTDI chip in bit-bang mode because it still uses the host CPU to compute timings) it will stay under 1%.

By going serial or USB way you don't have to take care of parallel cable quality and length.