IF150 USB-Serial Interface (Suggested Design and Self Build Project)
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.
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.
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:
8 data bits
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.
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.
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.
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
Bottom side view
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
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
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.
And here they are assembled into the case.
Final Suggested Design Overall View
If you implement this suggested design then you should end up with something looking like this.
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.
The Firmware I am releasing as Careware/Charity
Ware. To obtain the Firmware then all that is required is a