About Active Bits Limited

Active Bits was formed in Cheltenham in 2012 and has since been designing electronics and software to help customers bring advanced products to market faster.

Steve Stone has more than 30 years experience designing electronics and software for embedded systems and worked with products from the likes of Microchip and Altera since their earliest devices were available in the mid 1980's.

Since then he has worked for defence, security, high-tech printing and research companies specialising in embedded design and real-time systems.
Active Bits can do the same for you.

A brief explanation of the services offered follows:




Appearing in almost every situation where low-cost, real-time control is required, microcontrollers vary from the simplest devices with a few bytes of RAM and simple programs to those with huge resources and capable of running real-time operating systems.

Microcontrollers are microprocessors with the built-in peripherals, RAM, clocking, timers and program memory. Most microcontrollers have some analogue interface capability having at least one ADC but they may also have PWM, DACs, op-amps and comparators too.

Steve has been working with dsPIC and PIC Microchip  microcontrollers since the 16F84 was introduced in 1995. Development & debugging is usually carried out in MPLAB X.

As the devices are generally programmed in C or C++ this means that  the function of the board can often be changed without having to redesign the PCB.

Microcontrollers can generally be optimised for low power or high speed and usually have good support for external peripherals.

Having so many features internally helps to reduces both the size and cost of the board as well as the PCB design time.



DSPs are targeted at signal processing. Consequently they generally run faster than microcontrollers and often have fewer built-in peripherals although most have sophisticated serial protocol hardware (UART, SPI, I2C etc). What DSPs apart is that their architecture allows for faster computation using logic optimised for arithmetic, particularly data in vector format.

Enhancements include SIMD (instructions that can work on multiple sets of data at the same time), fast DMA transfers, high-speed cache memory, dedicated hardware computations blocks etc). This makes them particularly suitable for Fourier transforms, digital filters, image processing etc.

There are some microcontrollers with some built-in enhancements, particularly hardware multipliers and sometimes dividers, which help them cross the performance gap towards the lower spec DSPs. Microchip's dsPICs are an example.

Steve has particular experience with Analog Devices Blackfin, SHARC (including 3-core devices with built in FFT hardware) and dsPICs.

As DSPs tend to have more internal memory, external memory busses and faster clocks, it can be easier to use them with real-time operating systems.

Steve has been writing software for these since 2005 in C and C++.

Embedded Software

Steve has been writing software for microprocessors, microcontrollers and DSPs since 1985. Mostly in C and C++ but also in assembler where necessary in order to extract maximum performance.

Many of the applications have been 'baremetal' i.e. just the code for the application, but sometimes development can be speeded up for more complex applications by using a Real-Time Operating System. This is particularly true when there are other software modules available for USB, LAN communications.

Many RTOS offerings have to be paid for either by purchasing a license for a specific processor or family or by paying a royalty fee for units shipped.

Systems I have designed / coded have used Express Logic's ThreadX RTOS and Analog Devices' VDK.


LabVIEW is a software language that is written graphically - i.e by 'wiring' almost as though entering a schematic for a PCB. It is excellent for rapid prototyping, proof of concept demonstrators, algorithm development, research and data acquisition and control.

The code is highly reusable and gives easy access to filing systems and high-level computer functions as well as low-level number crunching.

Steve often produces stand-alone executable code for clients using the Windows platform and there is no need for the client to have their own license.

Steve has many years' experience with using LabVIEW and obtained the CLAD qualification in 2013. Active Bits maintains LabVIEW professional suite to the latest version.