Practical Control Embedded Software, Electronics Design, and Product Design

Last month Practical Control delivered more electronics designs for the telematics market. GPS and GPRS based designs seem to be the theme at the moment with more and more clients requiring remote access to data. We have been designing GPS, GRPS, 3G units for the last 6 years and this has meant we are well placed to serve entrepreneurs and SMEs with optimised designs to conserve power and data rates.

Practical Control have been using the DICOM standard is recent work whilst displaying X-RAY information held in other proprietary equipment. DICOM stands for Digital Imaging and Communications in Medicine and defines how images can be shared between applications. It is used for all types of medical images that include cardiology, dentistry, endoscopy, mammography, ophthalmology, orthopedics, pathology,
pediatrics, radiation therapy, radiology, surgery, etc.

DICOM is an upper layer protocol which sits on TCP/IP. It allows query and retrieval of records/objects and defines the quality and consistency of images botn when displaying and printing.

Security is handled in DICOM by transport layer security (TLS). The TLS standard is currently TLS version 1.2.

DICOM is additionally being trialled for GP access to patient care pathways for recall of images from hospitals. This is being trialled in Hertfordshire. Further information can be found on the NHS Expo website.

Practical Control is currently working towards ISO 13485:2003. The primary objective of ISO 13485:2003 is to facilitate harmonized medical device regulatory requirements for quality management systems. As a result, it includes some particular requirements for medical devices and excludes some of the requirements of ISO 9001 that are not appropriate as regulatory requirements.

This will further strengthen Practical Control’s position in the product design and development of devices for Telehealth, assisted living and in vitro diagnostics.

All requirements of ISO 13485:2003 are specific to organisations providing medical devices, regardless of the type or size of the organisation.

The Continua Health Alliance has announced that it has chosen Bluetooth low energy and Zigbee as the two wireless standards for its next generation of interoperate devices.

The Continua current design guidelines include both Bluetooth and USB. The inclusion of Zigbee and Bluetooth low energy will mean lower powered devices can be developed for heart rate monitors, blood pressure monitors, activity monitors, bed sensors, fall detectors etc…

Continua has more than 190 members worldwide and is committed to interoperable devices for personal health.

Practical Control are pleased to announce that we are listed as one of the innovation knowledge base providers on Yorkshire Forwards innovation voucher scheme.


This means that we are able to provide specialist help to companies seeking research and feasibility studies that lead to innovation.


A voucher covers upto £3000 expenditure and can be used to purchase an academic’s expertise to help deliver a knowledge solution to an innovation project. This expertise will come from approved suppliers in the knowledge base institutions within the region, including universities, further education colleges and research and technology organisations.

If you are looking to research or undertake a feasibility on an electronic product design, think that you require specialist knowledge based help then find out more here.

Bluetooth low energy is an emerging technology to enable low power wireless communications between mobiles, PDAs and sensors. Bluetooth low energy (BLE) was previously known as Wibree by Nokia. Chipsets can be either single mode which implement the lighter BLE stack or dual-mode i.e. interoprates with both BLE and conventional bluetooth.


The significant points of BLE are that it:-

A useful factsheet is available that covers the difference between bluetooth and BLE.


BLE is aimed at low power devices, examples being Telehealth, Fitness, and Personal security.

Accessory Protocol

The iPod uses an accessory protocol to facilitate communication between the iPod and attached accessories. The protocol was introduced in third generation iPods and is accessible either from the dock connector or the serial port located next to the headphone jack.

Communication is implemented using an 8 data bit – 1 stop bit serial protocol at a standard rate of 19200 baud.

Command Structure

To communicate with the iPod a message consisting of the following elements is needed:

Sync Byte: 0xFF
Sync Byte: 0×55
Length (1 Byte): Mode + Number of command bytes + parameters.
Mode (1 Byte): Modes available include 0-4 and 9.
Command (2 Bytes):
Parameter (n Bytes): Optional
Checksum (1 Byte): Subtract from 0×00 in the following order: Length, mode, command, parameter.

Available Commands

A variety of commands can be issued to the iPod and each command is grouped into a ‘mode’. The commands available in modes 0 - 2 are as follows:

Mode 0 – Mode switching commands

0×01 0×01 – Switch to Voice Recorder mode (not available on 5th Generation)
0×01 0×02 – Switch to Remote mode.
0×01 0×04 – Switch to Advanced Remote mode.
0×03 – Get mode status.
0×05 – Switch to Advanced Remote mode.
0×06 – Switch to Remote mode.

Mode 1 – Voice Commands

0×01 0×00 – Recording started.
0×01 0×01 – Recording stopped.

Mode 2 – Remote Commands

0×00 0×00 – Button released.
0×00 0×01 – Play.
0×00 0×02 – Vol+
0×00 0×04 – Vol-
0×00 0×08 – Next track
0×00 0×10 – Previous Track
0×00 0×20 – Next Album
0×00 0×40 – Previous Album
0×00 0×80 – Stop
0×00 0×00 0×01 – Play
0×00 0×00 0×02 - Pause
0×00 0×00 0×04 – Toggle mute
0×00 0×00 0×20 – Next Playlist
0×00 0×00 0×40 – Previous Playlist
0×00 0×00 0×80 – Toggle shuffle
0×00 0×00 0×00 0×01 – Toggle repeat
0×00 0×00 0×00 0×04 – Turn off
0×00 0×00 0×00 0×08 – Turn on
0×00 0×00 0×00 0×40– Menu
0×00 0×00 0×00 0×80 – Select
0×00 0×00 0×00 0×00 0×01 – Scroll up
0×00 0×00 0×00 0×00 0×02 – Scroll down

Example command messages

Switch the iPod into remote mode:

0xFF 0×55 0×03 0×00 0×01 0×02 0xFA

Send the ‘Play’ command in Mode 2:

0xFF 0×55 0×04 0×02 0×00 0×00 0×01 0xF9

Send the ‘Button released’ command in Mode 2:

0xFF 0×55 0×03 0×02 0×00 0×00 0xFB

The ‘button released’ command should be sent within 3ms of sending a button command.

The iPod dock connector allows a variety of accessories to be connected with the iPod which can offer enhanced functionality. The connector connector uses 30 pins; the function of each pin is given below.

Note: Your connector may be reversed, so always check before connecting anything! Damage may be caused to your hardware if you connect the iPod incorrectly.

Practical Control have recently delivered a complex design using a mixture of Texas DSP and Xilinx FPGA processors. The product used the in-house team’s expertise to develop the 8 layer PCBs which sample and process signals at 400ns intervals as required by the client.

Developed using BGA and 0402 components, the first off production runs were manufactured and tested on site.

Our client will be incorporating the product into the realisation of a 10 year research programme for the aerospace industry.

Practical Control have recently developed electronic accessories for the iPod and iPhone devices.
The embedded software development team are embarking on various new and exciting projects in this area and we will post more when we have further information!