Interfacing with LCD to debug
 

OK, I'm still very interested in this. I would like to know:

1. HOW to interface an LCD to the robot. (TTL port?) I really need to know how to wire it to the robot.

2. how to talk to the LCD in programming.

*note that I'm not a programmer, but I can relay the information to our team programmer. So, an idea or some sample code would be helpful.

Re: Interfacing with LCD to debug
 

Here's a demo example we used on a Vex robot a couple of year's ago: http://team358.org/files/programming/Vex_LCD_Demo.zip

The particular LCD we used was wired to digital input 16 and didn't use either serial port. It was a lesson on the basics of serial communication.

The README.txt file talks about the communication.

We used a Scott Edwards Electronics, Inc.

Re: Interfacing with LCD to debug
 

Thank you. That may come in very handy.

Re: Interfacing with LCD to debug
 

Sorry, I had to add a P.S. to my post.

The example was used as a lesson on the basics of serial communication and didn't use either serial port. It used a single digital output pin to transmit serial data to the LCD module.

If you use the TTL port instead then you can take advantage of the built-in serial support.

Re: Interfacing with LCD to debug
 

Yes, since there is no camera this year. (or at least no camera is really needed to track a green light) Then, I am thinking about "stealing" the port and use it for a cool LCD. Hopefully we can come up with a neat way to display errors, for real time debugging. But, it could at least display our team number. :D

Re: Interfacing with LCD to debug
 

I'm not too familiar with the processor in the RC but I use USART for my hobby projects. I just send a string to a for loop and it transmits at a specific baud rate.

Re: Interfacing with LCD to debug
 

Spark Fun Electronics has a bunch of LCDs available. If you look for the ones labeled "serial enabled", then it is trivial to connect them to the FRC controller, or a Vex controller. Then you just use the "print()" function (making sure it goes to the right serial port) and whatever you print out shows up on the controller. There are a few escape sequences you can print to do things like clear the screen or move the cursor around.

Re: Interfacing with LCD to debug
 

Have you successfully changed the splash screen on one of SparkFun's serial LCDs?

Re: Interfacing with LCD to debug
 

Ok, I think I am going to either get this one

http://www.allelectronics.com/cgi-bi...W-GREEN)_.html

or this one

http://www.allelectronics.com/cgi-bi...ACKLIGHT_.html

Does anyone know how to wire it up? I have no idea which pins go where. This is my first time working with LCD's. Now that I have chosen a specific model I'm hoping someone can help me out.

Re: Interfacing with LCD to debug
 

i have a more general question...how can i write and send a text command to the built in TTL port on the rc? without going into detail, a GPS reciever using the standard NMEA protocol accepts TTL ASCII text strings as commands, and sends the serial amswers back...how would i go about reading and writing from the TTL port like this, or at least use a digital pin to do this?

Re: Interfacing with LCD to debug
 

This depends on your code. If you are using Kevin's serial_port.c/h library, then the instructions are in the file. Basically make sure you have ENABLE_SERIAL_PORT_TWO_TX defined for writing and ENABLE_SERIAL_PORT_TWO_RX defined for reading, and have the appropriate baud rate set. Then you set the global variable "stdout_serial_port" to the value of "SERIAL_PORT_TWO". After that, any printf() will go to the TTL line instead of the debug line. Please note, however, that it's possible I'm getting ports ONE and TWO mixed up.

Re: Interfacing with LCD to debug
 

thanks! that really helps a lot!


also, does that send to the TTL port that the CMU cam uses? or does it send to the porgram port (rs232)?

Re: Interfacing with LCD to debug
 

Where do I wire up the TX and RX lines of the TTL port to the LCD?

Re: Interfacing with LCD to debug
 

Based on the diagram, that LCD is not compatible with the TTL port. The diagram shows it wired to a "printer port", which is a parallel interface. The TTL port is a serial port. (It may be possible that the LCD also has a serial interface, not shown in this diagram.)

A byte consists of 8 bits. A parallel interface uses 8 pins and sends all bits at the same time (plus some control pins). A serial interface uses 1 pin and sends each bit in sequence.

You could still use the RC to control this LCD, but you would have to use the digital I/O pins, not the TTL port.

Re: Interfacing with LCD to debug
 

I'm pretty sure it has serial capabilities too. I will try and find the serial diagram when I can. But, I would like to know how to use the digital I/O pins too. how would i wire that up?

Re: Interfacing with LCD to debug
 

Precision Guessworks (1646) has a touchscreen LCD on the way along with our co-processor. The goal is to use it for diagnostics and debugging. We went with a Gumstix (LCD, interface, and co-processor) solution similar to what AdamBots (245) did in 2007.