Problems with Serial Graphic LCD 160x128

Archive SparkFun Site Questions/Comments
1

Yes, I’ve a question. I’m using Parallax’s Propeller chip to talk to Sparkfun’s Serial Backpack attached to Sparkfun’s Graphic LCD 160x128. I can get everything to work except for two of the most important (to me) functions on a large LCD: CR & LF. When I send a 0x0D or 0x0A to the LCD, it prints two garbage characters. What gives? I know it’s not my code because I’m running parallel streams to a terminal debug and a Parallax 4x20 LCD. Both the terminal and Parallax LCD handle the CR & LF correctly, but Sparkfun’s Big Bertha…not so good.

Strangely, however, BS (backspace 0x08) does work. Was the omission of CR & LF done for a reason? How are you at Sparkfun central handling carriage returns/linefeeds on this big girl?

2

The serial backpack supplied on the HUGH LCD graphic display has 2 critical omissions in its code. You can’t get get Carriage Return ($0D) or Linefeed ($0A) to work. If you attempt to use them in your serial outputs, you get garbage characters on the screen instead of returning to column 0 at row + 1 (CR) or moving down a row (LF).

I’ve looked at the code supplied and it appears CR was handled properly in an earlier version–quite possibly the version with the foul language added as a bonus for curious customers (tsk, tsk, Nate), but had been removed for the published version.

I thought I might attempt to fix the code myself, and even bought a programmer for the chip, but since the 6 ICP pins were not included with the board, all I’ve got is six holes, and it’s durn near impossible to unsolder the backpack from the LCD to be able to solder the 6 pins where they belong.

If you’re at all considering buying this thing, I’d advise you wait until SparkFun gets around to fixing this. A serial backpack that doesn’t do CR/LF is embarassing, and if they’re not going to include the ICP programming pins, then they shouldn’t permanently solder the backpack to the LCD–put Male/Female connections on the LCD & backpack.

3

Are you still wanting CR/LF processing in the Graphic Serial Backpack? At the moment, I’m set up to make changes (having fixed some serial buffer management problems, added flow control, and fixed a line-drawing bug). I could add CR/LF also.

– Carl

4

In case this is helpful,

I just recently desoldered the backpack on my display using just a soldering iron.

First off the backpack had slight corrosion on some of the pads probably from whatever flux SF uses to attach the board. That kinda bothered me. Also the backpack was mounted slightly crooked.

I decided to put connectors on the two devices.

I use a 800 degree F tip to do all of my soldering, so that would make a big difference when attempting this.

I used masking tape to protect the display from flying flux.

I use isopropyl alcohol to clean my boards afterward, but I couldn’t dunk the display like I normally do, so the tape helped.

I held the display elevated above the bench so gravity would pull the backpack away from the board when it was ready.

(I thought it would just fall but the connector holes on the backpack aren’t a complete match to the display holes)

(The connector is 11 x 2. The 11’s axis pitch was correct but the 2’s axis is off.)

I gobbed on the solder and went back and forth a couple times till the backpack tilted and then I slowly pulled it away from the display. Taking the pins out of the packpack was pretty easy. Almost the same method except I used pliers on individual pins.

Then I used a solder sucker to open the holes. (The spring activated type)

Solder the new connectors using the boards as guides (remember, the holes are wrong, so there are small angles to consider.)

I cleaned the display by soaking the connector side in alcohol for 10-15 mins and slowly brushing the area with a toothbrush. Display was only as deep as the connector!!! (No alcohol on the display area!!)

Also, if you need to program the board without removing it, you can use those ‘pogo’ pins…

Dave