Paralell 2 line LCD

hmlittle59

Hello All,

I have my new PCB's (48 pin) but they are for the Parallax Serial 2 line LCD. Reading over the Command set, I'm trying to figure out if this chip can drive a standard Parallel LCD without an additional daughter board attached to it? I see that Parallax sells a Parallel LCD but it's for the same price as the serial, I thought they are suppose to be cheaper? I see Commands in the manual but are they for a Parallax.com version of and Parallel LCD? Reason: I was able to purchase some Displays for future designs ($10.00 per) and was hoping this chip (BS2 48 pin) would work. The cost savings from $30.00 down to $10.00.

Thanks for any help

Howard
www.GarageDoorValet.com

RDL2004

I assume when you say 48 pin you mean that you are using a OEM interpreter chip. I think all the 48 pin OEM chips support the PBASIC LCD commands which allow you to control HD44780 compatible displays in 4-bit parallel mode. However, a parallel LCD will require 6 or 7 lines to control. If your boards are already made with the intention of using a one line serial connection, using parallel displays will probably be a problem. Your future board designs could incorporate the extra control lines though.

There are newer LCD controller chips being used which offer serial modes (SPI, I2C) in addition to the older HD44780 compatible parallel mode. You might check to see if your new displays can do this.

One company I know of that makes serial LCD displays is Newhaven (they apparently use a PIC 16F690). If your new displays can only operate in parallel mode, there is always the option of using an add-on "backpack" or daughter-board to use them with a one line serial connection. These generally run $15 or less, so there may still be some cost savings.

hmlittle59

Hello RDL2004
Pins will not be a problem, the next version of this PCB needs 2 more I/O pins and with that there will be 8 pins + the current (3) from serial comm. still unused. So I will be OK in that area. I'm also trying to figure out were the character set is coming from. Are they all contained in the OEM interpreter chip. I'll be displaying (text,numbers,symbols). I do not want to add a $15.00 daughter-board as that would take my cost back up. I bought these current LCD's a couple of years ago, so they may not have the (SPI, I2C) that your referring to. Just did a quick look at the Newhaven link and they look good, thanks. I check them out also. I'll be studying the manual some more to make sure the 48 Pin will do all that I want.

thanks again

Howard
www.GarageDoorValet.com

RDL2004

Generally, with HD44780 compatible controllers, the character set is in the controller (CGROM). There is also some CGRAM you can program with up to 8 custom characters. Since it's RAM, your program has to reload the custom characters every time power is cycled. My Basic Stamp manual says the LCD commands are only for the BS2P, so you'll have to check to see if they work on whatever version you have. Also, those built-in commands only work with HD44780 compatible controllers (most are compatible).