Dangerous Prototypes

Other projects => Past projects => USB serial LCD backpack => Topic started by: Sleepwalker3 on January 16, 2012, 10:18:25 am

Title: LCD Backpack for 16 x 2 LCD?
Post by: Sleepwalker3 on January 16, 2012, 10:18:25 am
It appears that the LCD Backpack is only for 20 x 4 LCD's, can it also do 16 x 2 or even 8 x 2?
Title: Re: LCD Backpack for 16 x 2 LCD?
Post by: ian on January 16, 2012, 10:38:54 am
It should initialize any multi-line LCD correctly. It should work with many standard memory maps, but there is a huge variety out there. The Matrix Orbital protocol doesn't have commands to setup the memory map, I'm not sure what other designs do when there is a different memory map.

I think the best solution is to have a simple serial terminal interface where you can enter the lines (1 or multi) and line locations. That can be stored in EEPROM and be reloaded on startup.

Do you know the memory map locations of your displays? I can make you a hard-coded firmware for now.
Title: Re: LCD Backpack for 16 x 2 LCD?
Post by: Sleepwalker3 on January 17, 2012, 01:09:21 am
Thanks Ian,
I haven't actually tried it, but I couldn't see any info that suggested it would run 16 x 2 and everything just showed 20 x 4. I have both 2 and 4 line LCD's and was looking to have a serial backup for them. I'd been looking at making / buying the Sparkfun unit, but they have some issues with updating their circuits/firmware/PCB's to all match, then I stumbled upon your unit.
I couldn't see anywhere where it said it would do 16 x 2, so figured I'd ask. SF have two different versions of firmware, 1 for 20x4 and another for 16x2, so that's how they do it.

The 16 x 2 display I have is an RT162-7 and I'm told it uses the same commands as the HD44780U, so should be pretty universal by the sounds of it. I'll look at getting one of your boards and seeing how I go with it.

Thanks for your help!  :)
Title: Re: LCD Backpack for 16 x 2 LCD?
Post by: sqkybeaver on January 17, 2012, 03:48:18 am
mine is working with a 16x2, soon to be tested with a 2x40
Title: Re: LCD Backpack for 16 x 2 LCD?
Post by: ian on January 17, 2012, 07:51:43 am
I also tested with a 16x2 LCD display and it worked fine using the standard firmware. I think most newer displays have a consistent memory map, but definitely not all of them.
Title: Re: LCD Backpack for 16 x 2 LCD?
Post by: Sleepwalker3 on January 18, 2012, 07:31:39 am
Thanks guys, that's great.

I wonder has anybody tried this on an 8x2?
Title: Re: LCD Backpack for 16 x 2 LCD?
Post by: ian on January 18, 2012, 07:49:47 am
Many 8x2s will probably work. The only kind known not to work "out of the box" at displays that need to be initialized as a single line (1x8), and that can be fixed with one tiny change in the firmware.
Title: Re: LCD Backpack for 16 x 2 LCD?
Post by: Sleepwalker3 on January 20, 2012, 12:58:35 pm
Thanks Ian, sounds good to me :)

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