Developing a Manufacturing Test System for Wireless Multimedia Tablet Devices

Darragh McShane, Benetel

"The most significant advantage of PXI for our products lies in the fact that it offers a compact and reliable means of incorporating all of the diverse testing requirements of a typical wireless test system into one neat, rack-mountable package."

- Darragh McShane, Benetel

The Challenge:

Developing a manufacturing test system to test a wireless multimedia tablet device that incorporates a complex touch screen, accelerometer, camera, audio and Wi-Fi requirements.

The Solution:

Using PXI and PCI Express products from National Instruments to develop an innovative automated test solution to verify a broad range of multimedia device functions ranging from LED colour and intensity measurements, touch screen calibration, audio loopback testing, and Wi-Fi and proprietary RF measurements to camera, accelerometer, charging current circuitry and USB port functionality.

 

Benetel engineers are global specialists in wireless design and developing innovative automated test equipment (ATE) solutions across a wide range of industries and products. The ever-increasing use of wireless multimedia devices has spurred a significant increase in our ATE business, which has prompted the development of mass production turnkey test solutions designed to efficiently test diverse consumer products including wireless modules, smartphones and touchscreen multimedia devices.

 

This case study focuses on a touchscreen multimedia tablet application that requires a two-stage test system to measure the RF performance of the device at the printed circuit board (PCB) level and a final functional test stage to verify the full functionality of the device when the PCB and screen are assembled into the external plastics. The PCB-level stage is based on NI PXI technology and the final functional stage is PC-based and uses NI vision and NI-SWITCH hardware and software tools.

 

The RF performance measurement system carries out fundamental tests such as LED colour and intensity measurements, battery voltage, charging current, audio path, accelerometer, Wi-Fi (including error vector magnitude (EVM), bit error rate (BER), TX output power, adjacent-channel power (ACP) and Spectrum Emission Mask) and a number of proprietary RF tests. The final functional test system performs MAC address programming, downloaded customer application code programming, full audio loopback, USB port testing, and camera and screen functionality testing. The screen test checks for dead pixels using a GigE camera and NI Vision software by carrying out a pixel comparison with a golden image stored on the ATE.

 

Both test systems are based on the Benetel Common Test Platform, which is a powerful, flexible software developed in NI TestStand and LabVIEW software with active support for applications requiring multithreading, database connectivity and test fixture control. Using a common software platform helps us radically cut development time on new projects by up to 75 percent and facilitates delivery of a high-quality, proven end product.

 

Each test system makes significant use of National Instruments hardware and software. The first PCB-level test is based around an NI PXI system using the NI PXIe-5663E vector signal analyser and the NI PXIe-5673E vector signal generator modules for Wi-Fi and proprietary RF testing. These modules use the NI WLAN Measurement Suite to carry out a full suite of tests to 802.11a, b, g, or n specifications. Additional modules include an NI PXI-6529 data acquisition module, an NI PXI-2548 general-purpose switch module and an NI digital I/O module. These are used for ancillary functions such as signal measurement, fixture path switching and test fixture control.

 

The final functional stage is PC-based and uses an NI PCI-6520 industrial digital I/O board to control the test fixture. The system uses key functions of the Benetel Common Test Platform in tandem with NI vision and NI-SWITCH software to simplify complex touchscreen calibration along with camera and screen verification operations.

 

We are market leaders in the provision of shielded enclosures for testing wireless devices and we have a range of products to suit a wide scope of customer applications. The PCB-level tester makes use of the Benetel BTS-130 enclosure, which provides more than 80 dB of shielding in a compact, rugged, pneumatically assisted enclosure. Using this shielded enclosure on the PCB-level tester is intended to allow independent parallel testing of the units under test (UUTs) by simultaneously testing two or more UUTs in close proximity without incurring test failures due to cross interference.

 

This parallel test approach, which forms a core part of our production test strategy, greatly increases overall throughput while keeping capital costs to a minimum. In addition, using autoscheduling within NI TestStand increases the efficiency of testing operations by automatically scheduling the order parallel tests execute in, minimising test time and further maximising resource utilisation.

 

The final functional test stage uses our latest BTF-930 vision-based enclosure, which is a rack-mountable fixture designed for use in camera and touchscreen calibration and verification activities.

 

The Benefits of Using NI Equipment

NI PXI technology forms a fundamental part of our test strategy across a broad range of applications and industries. The most significant advantage of PXI for our products lies in the fact that it offers a compact, reliable means of incorporating all of the diverse testing requirements of a typical wireless test system into one neat, rack-mountable package. Also, the relatively low development overhead associated with PXI drivers coupled with the widespread availability of LabVIEW built-in tools and toolkits leads to a highly cost-effective system when compared to any alternative method available. Furthermore, PXI’s modular approach helps future proof the test system design so additional functionality or capacity can be easily added without requiring a costly redesign of the overall system. This is an important factor given the fast-moving pace of development in the wireless industry.

 

Using NI vision and GigE camera technology as part of our ultra-versatile vision system also allows full verification of the latest multimegapixel, high-definition touchscreens and cameras in a compact, cost-effective, rack-mounted package. Other factors in choosing NI products as the basis for both systems centred on the availability of effective after-sales support and the ease of interfacing with the Benetel Common Test Platform.

 

Our wireless multimedia device test systems (RF performance and final functional stages) represent fast, powerful and flexible mass-production, turnkey solutions designed to test complex multimedia tablet devices. Each system is automated and sequenced for maximum test efficiency ensuring that the overall unit cost of production is minimised while enhancing test repeatability and reliability.

 

Author Information:

Darragh McShane
Benetel
Guinness Enterprise Centre, Taylors Lane
Dublin 8
Ireland
Tel: +353 14100668
darraghmcshane@benetel.com

Benetels manufacturing test system incorporates a complex touch screen, accelerometer, camera, audio and Wi-Fi requirements.