Summary of Message Pump using PIC16F687 microcontroller
The Message Pump, also known as the USB to LCD Backpack, connects an LCD display directly to a computer using a PIC microcontroller and an FTDI USB-to-serial chip. It features cross-platform driver support for Mac, Windows, and Linux via a virtual COM port. Users can send ASCII data or specific three-byte instructions to control display formatting, baud rates, and Hitachi commands. The device is easily tested with terminal software or the provided Processing example.
Parts used in the Message Pump:
- LCD display
- PIC micro-controller (PIC16F687)
- FTDI USB to serial chip
- Computer
- Hyper-terminal or terminal software
- Processing library
Brief:
The Message Pump A.K.A. the USB to LCD Backpack is a device that allows you to connect a LCD display directly to your computer. It uses a PIC micro-controller, to drive the LCD and a FTDI USB to serial chip to connect to your computer.
The great thing about the FTDI chip is that it’s drivers are available for Macintosh, Windows, and Linux! The FTDI chip works by creating a VCP (virtual com port) and you may already have these drivers on your computer if you use an Ardunio Diecimila. If not, no worries they are free and and easy install.
What does it do?
Once a VCP is opened to the Message Pump any ASCII serial data sent to it is displayed on the LCD display.
This means that if you have software on your computer that can access a serial port you can display messages on the Message Pump!
The possibilities are endless, imagine using AppleScript, Processing, Basic or whatever your preferred programming / scripting language is, you could display messages like;
How many e-mails you have- The current date and time
- CPU temperature
- RSS feeds
- Hits on your web page
- ….
How many e-mails you haveHow to use it-Basics:
The easiest way to use the Message Pump is to open Hyper-terminal or an other terminal software, select and open the COM port for the Message Pump, then just start typing. What you type is displayed directly onto the LCD display. If you are using other software you will have to check how to open a serial port in that software.
To get you started I’ve made a simple Processing example. It is called MessagePumpDemo.pde and uses the Serial Library included with Processing.
The way MessagePumpDemo works; first it lets you select a serial port, then it opens that port at the default baud rate of 9600 bps and prints pumps out a message. It also lets you send keystrokes to the display. It’s a building block for you to examine and make better.
How to use it-Advanced:
The Message Pump also accepts instructions to control settings and formatting. These are used to change things such as the size of display, for example 1×16 to a 4×20 character display, baud rate etc. You can also jump to a specific space on the display. The instructions also include the ability to pass though, Hitachi commands right into the display. For example; clear display, shift left etc.
An instruction is always three bytes long and it always starts with the hex value of 0x80. The next value is the instruction and the third is the value of the instruction.
For more detail: Message Pump using PIC16F687 microcontroller
- What hardware components drive the Message Pump?
The device uses a PIC micro-controller to drive the LCD and an FTDI USB to serial chip to connect to the computer. - Does the Message Pump work on all major operating systems?
Yes, the FTDI chip drivers are available for Macintosh, Windows, and Linux. - How does the FTDI chip connect to the computer?
The FTDI chip works by creating a VCP (virtual com port) which allows the system to recognize the device as a serial port. - What happens when ASCII serial data is sent to the Message Pump?
Any ASCII serial data sent to the open VCP is displayed directly on the LCD display. - Can I use programming languages like Processing to control the display?
Yes, you can use AppleScript, Processing, Basic, or any language that can access a serial port to display messages. - What is the easiest way to test the Message Pump?
The easiest method is to open Hyper-terminal or other terminal software, select the COM port, and start typing. - What information does the provided Processing example demonstrate?
The example lets you select a serial port, opens it at 9600 bps, prints a message, and allows sending keystrokes to the display. - How many bytes long is an instruction sent to the Message Pump?
An instruction is always three bytes long. - What value starts every instruction sent to the device?
Every instruction always starts with the hex value of 0x80. - Can the Message Pump execute Hitachi commands directly?
Yes, the instructions include the ability to pass through Hitachi commands like clearing the display or shifting left.
