IF150 USB-Serial Interface (Suggested Design and Self Build Project)

LEGAL NOTICE

This IF150 Interface suggested design is exactly this. It is a design solution suggested by Nick Bailey for which he takes no legal liability makes no statements about any safety or RFI emissions conformance and gives no warranty about performance and its suitability for the intended application. This suggested design is offered "AS-IS" and anybody who wishes to implement and use this design does so entirely at their own risk and accepts full responsibility and liability for their actions in implementing and using the suggested design and any consequential events or matters arising from their actions. It is the sole and total responsibility of anybody using this design to fully satisfy themselves that the design is safe to use and the intended application is appropriate. In your use of this design you are also agreeing to "save harmless" ("hold harmless") Nick Bailey, his family, any family business and anyone else personally associated with him.

General

The IF150 Interface is my own design suggestion for USB 2.0 to Lowe HF-150 receiver interface to replace the original and now very rare Lowe IF-150 Serial Interface.

If you have any question or suggestions then please email me.

Unlike the original IF-150 interface the suggested interface design is a native USB 2.0 interface not requiring any additional USB to Serial converter hardware. In addition there is no additional Window's driver software required to be installed on the PC. A simple .INF file will take care of everything. The design should work on both Windows and Linux operating systems. Other devices and operating systems may also work with the suggested design.

The HF-150 receiver does not have a true RS-232 serial interface port. This suggested IF150 Interface design takes care of the required conversion between normal RS-232/serial data flow and the PPM (pulse position modulation) data stream required by the receiver.

The suggested hardware design includes opto-isolation providing total electrical and conductive noise isolation, thus ensuring no noise/interference is injected into your receiver via the interface.

I was originally going to produce and sell the IF150 Interface myself but international approvals (UL & CE) and product liability insurance for "finished end products" (be they final or prototype offerings) were legally required. I was advised that I could not build/manufacture a product, even if I gave it away, without CE approval in Europe and possibly UL approval in America. Interestingly the Raspberry Pi faced the same issues. See here: http://www.raspberrypi.org/archives/878

I am thus publishing the IF150 Interface as a suggested design and self build project.

Compatibility

I can only say that this suggested design works for me and my Lowe HF-150 receiver.

Software and Hardware Requirements

Any computer device fitted with a USB 1.0, 2.0 or 3.0 port should be hardware compatible with the suggested IF150 Interface design. Both Windows and Linux operating systems should work with the interface design.

Other devices/operating systems may work but I am unable to verify or guarantee this.

To drive the suggested IF150 Interface design requires any HF-150 compatible receiver control program, such as my HF150 Control Program, or any other program or a simple terminal program that is capable of sending supported commands to the interface.

Interface Commands and Features

The suggested IF150 Interface design together with the firmware supports all the same commands and protocol as the original Lowe IF-150 interface.

Lowe IF-150 Commands are:

FRQ - FRQ <value in kHz> <CR>
MOD - MOD <mode> <CR>
STO - STO <memory number> <CR>
RCL - RCL <memory number> <CR>

Lowe IF-150 Protocol:

1200 Baud
8 data bits
no parity
1 or 2 stop bits

Additional Commands:
Some additional commands may be supported (depending on final firmware) but they do not affect Lowe commands and these additional commands may eventually be used by my HF150 Control Program.

Additional Feature:
An additional feature of the IF150 Interface design is that USB data flow is bi-directional so the interface can talk back/respond to the sending program. An example of an already implemented command is IDENT. This identify command means that any driving program can identify and differentiate the IF150 Interface from the Lowe IF-150 and any other interface. Note! The IF150 Interface to HF-150 receiver is still and can only ever be a unidirectional send path.

Hardware Design / Implementation

The IF150 Interface suggested design is based on the Arduino Uno R3 module. This provides a top quality, well proven and tested base hardware platform to which my suggested design adds a daughter card with the necessary opto-isolation, level shifting and driver circuits to allow the interface to connect to the HF-150 receiver.

The required Firmware software is written by me using the Arduino Development Environment.

Interface Design Pictures

Here are a collection of images that show the component parts of the design and give an idea of the simplicty of the project to build.

Arduino Uno R3 Module

This is the heart of the suggested design. There is plenty of information about Arduino ( http://arduino.cc/ ) out there on the web. I chose the Arduino Uno as opposed to any of the other great little micro controller project platforms/kits because of the tight self contained USB interface. Also it is one of the smaller units available and the price is very competitive at around 20 UK Pounds, 30 US dollars or 20 Euros.

Arduino Uno R3 module

Opto-Isolation and Level Shifting Board

This board carries my electronic circuit design to allow the Arduino Uno R3 Board to safely connected to the Lowe HF-150 receiver.

The HF-150 receiver key pad circuitry to where this suggested interface design has to connect operates at a 12V level and is current limited to approximately 150mA. The Amtel AVR ATMega328P and family of processors input and output pins are not rated to source or sink more than 40mA or operate at more than 6V. Clearly some level shifting is required. At the same time it makes absolute sense to provide opto-isolation for electrical and noise isolation between the USB connection and the HF-150 receiver.

The electronic components are built onto the Arduino Proto Shield Board R3. As can be seen there are only eight components required plus a connecting cable. This board plugs on top of the Arduino Uno R3 Board completing the electrical design.

Top side View
Opto-Isolation and Level Switching Board

Opto-Isolation and Level Switching Board

Bottom side view
Arduino Proto Shield R3 with components

Circuit Diagram

Mechanical Packaging

Designing or finding good, effective and easy to build packaging is always a problem. Simple plastic cases, potting cases and so on are cheap and readily available but these often leave you with problems to solve like internal hardware mounting and a professional looking finish.

For my proposed design I have sacrificed cost and size for easy internal hardware mounting, minimal drilling (two holes only), no screws and a quality look.

The solution involves the use of the Arduino A000009 Case which is specifically designed to house Arduino modules.

Here is a view of the above boards and the case bottom together.
Arduino boards and case bottom

And here they are assembled into the case.
Arduino Boards assembled in case

Final Suggested Design Overall View

If you implement this suggested design then you should end up with something looking like this.
Final Looks

The smart label is optional but the Arduino case top has a purpose designed recessed label area so it seems silly not to make use of it.

Close up the case top cover looks like this.
Case top cover view

Firmware

The Firmware I am releasing as Careware/Charity Ware.

Full details can be found here.

Interested or Want to Build this Project?

If you are interested or want to build this project then you will need to read the IF150 Project Build information.

If you have any questions then I will be happy to try and answer them for you. My contact informaton is available at the bottom of this page.

Meanwhile, if you have a Lowe HF-150 Receiver, or any other interface compatible Lowe/other make of receiver then you might like to visit my HF150 Control Program page.

Contact Information

If you want to or need to contact me then please Email:

IF-150

nick-bailey

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