H19 Fibre Optic Microprocessor Shield

The OMC H19 Fibre Optic Shield, compatible with Arduino Uno, has been developed to allow an optical fibre datalink to easily be incorporated into a microprocessor-based design.

Why use an optical fibre link?

Many turn to wireless transmission to link short distance systems together. Although this can be convenient, there are applications where total confidence is needed in the integrity of the data transmission, both in terms of reliability of the data and in the security that the data cannot be easily intercepted.

Features of the the OMC H19 Fibre Optic Shield

▪ The transmitter used to send data is the OMC H19E2000BHR, a high power visible red transmitter optimised for PMMA (polymer) optical fibre. Being an LED and not a laser, it is much safer for use in an environment where people may unplug the fibre end. The visible wavelength is also useful for simple fault diagnosis.

▪ The receiver module used is the OMC H19R5000D, which has all the necessary drive circuitry built into the device and offers a digital output, ideal for interfacing with microprocessors. This all in one design simplifies the receiver circuit and avoids having to design and include the traditional pin diode amplifier and Schmitt trigger circuits needed to give a digital output.

▪ The shield is designed for use with the Arduino Uno and is stackable. It has jumpers for both the Transmitter and Receiver devices. With the jumpers fitted in position 1 (nearest to the board edge) the fibre optic transmitter is connected to the serial port (UART) digital pin 1 of the microprocessor. The fibre optic receiver is connected to the serial port (UART) digital pin 0. If the jumpers are moved to position 2 the shield PCB allows a link to be soldered between any of the I/O pins and the fibre optic Tx / Rx devices allowing complete flexibility of design.

▪ An example program is provided which shows a simple datalink, using the UART ports to transmit data over the optical fibre link. The data can be monitored either by using the serial monitor of the Arduino software, or the code is written to interface with a standard 16x2 LCD shield which can be stacked on top of the fibre shield.

▪ The shield can be used with any of the available microprocessor baud rates: 300, 600, 1200, 2400, 4800, 9600, 14400, 19200, 28800, 38400, 57600, or 115200. The actual fibre optic emitter and receiver pair can operate up to 5Mbd - the shield is simply a way of demonstrating the potential of incorporating an optical fibre link into a design.

▪ The shield can be used with PMMA cables up to 25 metres long in the standard configuration. For extended range OMC can offer a high power emitter option and also devices suitable for use with glass fibre if PMMA is not suitable in the application.

Relevant Part Numbers

Part Number	Description
OMFS11H19660D	OMC H19 Fibre Shield v1.1, 660nm Red Emitter with Digital output receiver
A09A91000A0	1mm core / 2.2mm jacket simplex PMMA cable assembly, 1 metre long with H19 connector each end
A09A95000A0	As above but 5 metres long
A09A910000A0	As above but 10 metres long
A09A925000A0	As above but 25 metres long
A08A91000A0	1mm core / 2.2mm jacket duplex PMMA cable assembly, 1 metre long with H19 connector each end
A08A95000A0	As above but 5 metres long
A08A910000A0	As above but 10 metres long
A08A925000A0	As above but 25 metres long

The H19E2000BHR emitter and H19R5000D receiver parts used in the shield can also be ordered separately to build into your own designs. Other cable lengths and alternative fibre/jacket types are also available on request. OMC can also offer the emitter and receiver parts in this shield mounted in alternative housings to connect with different fibre types.