BV4103	Serial LCD Display 16 x 2	Datasheet	£22.90
	Cool Blue LCD display having a true serial interface. This comes complete with the unique IASI (Intelligent Asynchronous Serial Interface). The interface is fitted to the back of the display and can be connected to a PC COM port or a microcontroller UART. The display is then controlled with simple single letter commands.		Qty:
	Size: 80mm long x 35mm wide x 25mm deep from front face to end of pins

BV4103-20	Serial LCD Display 20 x 2 - this item out of stock	Datasheet	£23.90
	Cool Blue LCD display having a true serial interface. This comes complete with the unique IASI (Intelligent Asynchronous Serial Interface). The interface is fitted to the back of the display and can be connected to a PC COM port or a microcontroller UART. The display is then controlled with simple single letter commands.		Qty:
	Size: 116 mm long x 35mm wide x 25mm deep from front face to end of pins

The following description shows a 16 x 2 character display, the 20 x 2 works in exactly the same what but is just a bit larger.

Specification

• Interface: RS232 or TTL 5V, 3V3 compatible
• Blue background with white lettering. White back light must be illuminated
• Voltage: 4.5 to 6V
• Current: 12.5mA with back light illuminated, 2.8mA with it off ***
• Size: 85mm long x 30mm wide x 25mm deep from front face to end of pins

*** This display requires the back light to be illuminated in order to see the characters.

A true Serial LCD Display. This is not only is this a serial display but a cool blue type. Will work directly from a PC COM port, a USB to serial converter or a microcontroller.

The display has a dark blue background and illuminated white lettering. It is a transmissive, negative type which looks extremely good but it does need the back light powered all of the time. It looks much better than the normal yellow / green types.

This shows the serial controller attached to the back of the display. There is a trimmer potentiometer that provides contrast setting and the serial connector is to the left.

The Serial Interface

The serial interface consists of 5 connections, of which, only four will be used at any one time. The connection details are as follows:

There are two interface options, RS232 via a standard PC COM port (Pins 4 and 2) or from a microcontroller UART (pins 1 and 2). As an example to interface to a standard 9 pin D type connector the following connections would be made.

RS232 9 Pin  LCD Pin 2 Pin 2 Pin 3 Pin 4 Pin 5 Pin 5 Short pins 1,6,4   Short pins 7 and 8

Only three wires are required from the COM port to the BV4102. There is no hardware handshaking so the pins in the above table should be connected together as indicated (1,6,4: 9 and 8). Connection to a non-inverted source would be similar except that pin 1 would be used instead of pin 4.

A non-inverted source would be the output form a microcontroller or the output form a USB/RS232 to TTL converter such as the BV101 or BV201. This device will plug directly into the BV101.

RS232 to TTL Convertor	USB to TTL Convertor
BV201	BV101

Software Interface - IASI2

As an example the device has been attached to a blue LCD display and connected directly to a BV101 and using the PC USB interface as shown in the picture:

When first connected the LCD displays the text that is stored in the EEPROM at location 0x10, this can be changed by the user to any required text.

To initialise the device the following takes place, this is done for this example on the terminal but could equally be done using software.

1. CR is pressed twice, this establishes the Baud rate, in this case it will match the terminal setting at 38400.
2. The first yellow square is CTRL-D (non-printable), this command tells the device to output in non-inverted mode, because we are connected to a USB to TTL convertor and not directly to a COM port.
3. The second yellow square is CTRL-A (non-printable), this tells the device to send its address which is the factory default to 'a', the device responds by sending a>. When a successful command is received the device outputs '>'
4. "ac1" has been typed in by the user, this will send a command to the LCD controller that will home the cursor and clear the display, the BV4108 responds with '>' -- which is on the next line
5. "at'Hello'" is input by the user, 'a' is the device address, 't' is the text command and 'Hello' is the text, the device responds with '>'
6. 'acc0' Is another command 'c' that send a command to the LCD display for the next line.

The result of the complete session is:

Full details of all of the commands are given in the data sheet, the IASI2 command set is shared between a few devices and so they can be 'mixes and matched' on the same serial bus. Up to 26 devices can be used on the same bus.