On this page...

Compact Digital Pulse Processing for Embedded X-Ray Applications

microDXP - Datasheet
(PDF format, 278KB, April 2018)

Get the latest microDXP Prospect release
Prospect releases are now accessible via the XIA Wiki Release page.

Get the latest microDXP Handel driver release
Handel releases are now accessible via the XIA Wiki Release page.

Documentation and Software/Firmware downloads   

The microDXP is a complete, low power digital spectroscopy system on a credit card-sized PC board. It can easily be incorporated into a wide range of embedded and handheld spectroscopy systems, lowering cost and speeding the time-to-market. Its small size allows for very compact assemblies and its low power consumption assures thermal stability and extended battery life.

The hardware design was completely overhauled in 2015. Faster clock speeds, a new 14-bit ADC, improved analog design and more processing power have yielded dramatic improvements in energy resolution, peak stability and throughtput! With these upgrades, the microDXP is now well-suited to work with the latest CUBE-based preamplifiers. The improved energy resolution also led us to introduce a spinoff product: The microDGF, optimized for high-resolution gamma-ray detectors such as HPGe.

As with all Digital X-ray Processor (DXP) Family instruments, the newest member includes digital spectroscopy amplifier and MCA functions. Additionally, the microDXP utilizes a PIC processor to handle communications, boot and dedicated acquisition routines and power management. The firmware for the FPGA and DSP is stored in a non-volatile flash memory that is factory preloaded but which can also be upgraded in the field. To minimize costs, many of the card's features are optional, so that only those that are actually required for an application need be purchased. In addition to serial I/O, the card also has some auxiliary digital I/O, including the capability for I2C, through which the microDXP can control external instrumentation. XIA would be pleased to discuss developing such DSP control code on an NRE basis.

The Development Kit includes the hardware and software necessary to get started with the microDXP. All customers must purchase a development kit with their first microDXP order.

Please contact the microDXP team at to discuss your application today!



Host software and drivers for the microDXP and microDGF


Datasheets, Manuals, Application Notes and Articles, as well as downloadable software and firmware.

Development Kit

microDXP / microDGF
Rapid Development Kit

Compact digital pulse processor for HPGe and other gamma-ray detectors
Single DXP channel with mapping functions, USB 2.0 interface and custom outputs.


  • Credit-card sized unit replaces shaping amplifier, pileup inspector and multi-channel analyzer.
  • Very high throughput: Up to 1 Mcps output count rate with random pulses.
  • User settable gain and pileup inspection criteria.
  • Peaking times from 100 ns - 24 us (with standard 40 MSPS ADC).
  • High level integration of control and acquisition parameters into reconfigurable sets that are stored in non-volatile memory. Stored sets are accessible with a single command to easily switch between corresponding data acquisition modes.
  • Accurate ICR and live-time reporting for precise dead-time corrections.
  • Real multi-channel analysis, allowing for optimal use of data to separate fluorescence signal from backgrounds
  • High-Speed USB 2.0 or serial RS-232 communications
  • Alternate IDMA parallel interface supports a wide range of communications including Universal Serial Bus (USB).
  • Real-time control via 4 general purpose digital I/O lines, two of which can be configured for industry standard I2C interface.


Inputs Analog

10k Ohms input, +/-4.0 V range (no input attenuation*)
Designed to work with common reset or resistor feedback preamps of either polarity.

*Other impedances and voltage ranges with on-board attenuation


Gate (TTL 3.3V) signal used to suppress data acquisition
4 general purpose digital I/O lines for custom applications

Data I/O USB 2.0 On-board USB 2.0 is available

RS-232 RS-232 Serial communications up to 921 kBaud

OEM OEM Option 1: Analog Devices high-speed serial port (SPORT) via the flat-flex interconnect
OEM Option 2: 16-bit IDMA bus; 4 general purpose digital I/O lines, two of which can be configured for industry standard I2C interface; connected via a high-density board-to-board connector. The microComU USB interface employs this connection.

Real-Time I/O 4 general purpose digital I/O lines, two of which can be configured for industry standard I2C interface
Digitizer ADC 14-bits at 40 MSPS standard
high-speed 80 MSPS option
Digital Controls Gain

Two gain options are available, combined with a digital fine gain adjustment ranging +/- 6dB
Gain Option 1 (standard): 25.5 dB range with 16 discrete computer-controlled gain settings
Gain Option 2: Fixed gain for embedded applications, lowest power consumption


DC offset adjustment: -4.4V to +4.4V
(For RC-decay preamplifiers; assumes no input attenuation)


Three triangular/trapezoidall filters are employed to suppress noise, and to detect and acquire baseline and energy data:
Fast Filter: fully adjustable, from 50 ns to 6.4 us*
Intermediate Filter: tracks with Slow filter, from 50 ns to 6 us*
Slow Filter: 24 pre-selected peaking times from 100 ns to 24 us*, with adjustable gap/dwell time

*These numbers assume standard 40 MSPS ADC, and should be scaled for 80 MSPS option.


A separate 12-bit (0-4095) threshold can be enabled/disabled and adjusted for each of the three filters


Two pileup rejection settings :
Fast filter time-over-threshold, aka maximum width, constraint
Interval-between-events, aka peak interval, constraint

Data collection MCA limits and number of bins
Dynamic Range
Data Outputs
MCA 256 to 8192 channels (32 bits deep)
Additional memory for sum or 2D spectra

Statistics Livetime, runtime, input counts, output counts, overflows and underflows

Diagnostics Oscilloscope, baseline distribution, access to raw DSP memory
Hardware Power Requirements +/- 5V @ 50 mA clean supply, or +/-5.25V @ 50 mA dirty supply to feed on-board regulators
+3.3V @ 150 mA

Dimensions 2.125" W x 3.375" L

Examples of Systems that Incorporate the microDXP

The microDXP miniaturized circuit-board can easily be incorporated into a variety of benchtop, portable, networked and embedded x-ray and gamma-ray spectroscopy data acquisition systems. In the first example the microDXP runs on the laboratory benchtop as a peripheral device. In the second example a more complex embedded system is considered. The I2C serial bus is used to control a ‘smart’ x-ray tube and detector HV bias supply, and the auxiliary digital I/O drives electromechanical or pneumatic components in real time based upon user defined metrics of acquired data.

Example 1. General-Purpose Spectrometer

In this example the microDXP and hardware included in the Development Kit act as a general-purpose digital pulse-processor, connected as a peripheral device under the control of a host computer. No specialized data acquisition modes are required, thus no firmware development is necessary.

XIA non-recurring engineering (NRE) required: None

User development required: Enclosure design

The microDXP, power supplies and microComU together constitute a digital pulse-processor that can be connected to virtually any controller with USB or RS-232 communications. Note: The microComU interface board included with the development kit falls into this category.

Fig. 1: A general-purpose spectrometer incorporating the microDXP. The microComU interface connects the microDXP to the host computer and power supplies.

Example 2. Dedicated Embedded Spectrometer

This example considers a materials sorting application where objects with certain pre-defined alloy ratios X, Y and Z are to be separated from others. An x-ray source irradiates incoming samples, and incident x-rays are collected by a solid-state detector connected to the microDXP. The microDXP is configured to assert a combination of its auxiliary digital I/O lines whenever the peak ratio X,Y, or Z is detected. The digital I/O lines drive electromechanical or pneumatic components in real-time to execute the appropriate mechanical operation, e.g. put the recognized object in the desired bin. User controls are limited to starting and stopping the system, and selecting one out of a small number of operating modes. Power supplies for the microDXP are also included. Finally, an external data port (e.g. RS-232) is also included so that ratios corresponding to new alloys can be defined, and new firmware uploaded without dismantling the hardware; or, alternatively, the microDXP could periodically be run in full MCA mode under computer control for diagnostic purposes.
This example demonstrates a system that uses a very small data acquisition command set (i.e. ‘start run’ and ‘stop run’) but that, conversely, requires customizations to the microDXP as well as significantly more user-designed hardware.

XIA non-recurring engineering (NRE) required:

  1. Customized PIC microcontroller code is required to implement the I2C peripheral device control.
  2. Customized PIC microcontroller code is required to implement high-level data acquisition routines controlledthrough the user pushbutton interface.
  3. Customized DSP code is required for peak ratio calculations, possibly implemented in lookup tables.
  4. Minimal FiPPI (FPGA) code modification is required to implement the auxiliary digital I/O functionality.

User development required:

  1. A more advanced interface unit is required to break out the microDXP high-density internal connection to standard RS-232, auxiliary and power connections. Still, this interface does not involve many active components, i.e. the I2C and auxiliary digital I/O are simply routed to additional connectors. The pushbutton interface might include an additional microcontroller, but could be implemented simply in logic.
  2. As drawn, the power supply is integrated on the interface board, with the same requirements as in the previous example. As stated there, optional voltage regulators for the analog circuitry are included on the microDXP for systems in which high-quality power supplies are not available.
  3. Again, some additional mechanical design, i.e. enclosure design, may be necessary.

Fig. 2: A system with a fully embedded host and user interface, with real time controls via the Auxiliary digital I/O.

Designing the system described above using conventional spectroscopy components would be a much more complex (and considerably more expensive) task, when compared with the solutions proposed here. Please contact the microDXP team at to discuss your application today!

XIA Home > Products > DXP Products > microDXP

Back to top of this page | Back to XIA home page.

http://www.xia.com/microDXP.html, last updated June 22, 2018
© XIA LLC 2016