Rugged Handheld Portable Military Computer
Hardware circuit board and embedded software, including OS, drivers and applications for a MIL-STD certified rugged handheld device.
A leading manufacturer of ruggedized computer, server, portable and network peripheral equipment solutions for military, industrial and commercial aviation applications.
The client had detailed requirements for a handheld Ruggedized Personal Digital Assistant (RPDA) for military applications in harsh conditions. Among the product’s features were a touch-screen LCD display, dual batteries, a TacLink® radio interface, a USB port, WiFi, Bluetooth, a compass, an accelerometer, a speaker and a microphone.
To be mission ready, the RPDA faced some rigorous size, weight and power requirements—known as SWaP in the military. The unit needed to provide powerful performance and a multitude of features in a small, lightweight, ruggedized package. It had to have long battery life (20 hours) and perform within strict power consumption limits. The charging circuitry had to charge two batteries—an external battery pack and an internal battery that powered the unit while a soldier hot-swapped the external battery pack—and the external battery pack had to power high-current expansion modules, such as the military’s TacLink® modem. The RPDA also had to support the Windows Mobile™, Windows CE™, and Linux with Android operating systems and pass difficult-to-achieve Department of Defense MIL-STD certification testing.
The client engaged RightHand Technologies to write the software and to design the electronics for the device. Other third-party companies handled additional aspects of the product development, such as mechanical enclosure design and battery design.
Among the challenges RightHand Technologies engineers faced with this project were:
- Extensively modifying the Windows Mobile board support package (BSP) to meet the customer’s specific performance requirements.
- Designing complex electronics with an extensive feature list for an extremely small product with a predetermined size constraint.
- Developing a very complex power section with specific power management, battery charging and power sourcing requirements.
- Ensuring MIL-STD certification for the circuit board, which included ruggedness (vibration, shock, etc.), temperature extremes, humidity and EMI.
RightHand engineers also had to assimilate and integrate the enclosure, internal cabling and batteries that the other contract organizations developed for the project, and in only four months, deliver working prototypes that could be demonstrated at a trade show.
Finally, at the end of product development, RightHand Technologies had to help ensure that the entire assembled system passed certification testing.
Departments in RightHand Technologies that contributed to this project were:
- Hardware: Designing, developing and debugging the circuit board, and integrating it with other elements of the entire system; and hand-assembling all the prototype units for field trials and MIL-STD certification testing.
- Software: Designing the system to support both Windows Mobile and Linux; writing numerous application program interfaces (APIs) on top of the Windows Mobile BSP to enable customers to create custom software applications that tied closely to the hardware; developing custom board-support software, including a bootloader with a diagnostic component and a custom splash screen; conducting device verification testing; and testing to certify that the software would meet Windows Mobile logo testing.
- Quality: Ensuring the board would meet Department of Defense MIL-Standard requirements; after MIL testing, working with the client to resolve system level issues related to the integration of components from other third parties.
RightHand Technologies’ engineers used their extensive experience in developing complex embedded electronics to produce creative solutions and conquer the challenges they faced with this product:
- Windows Mobile BSP modification: One of the major elements of the project was modifying the Windows Mobile BSP. RightHand’s software engineers worked very closely with their hardware counterparts to understand the performance requirements of the hardware and peripherals, and then modified numerous aspects of the BSP code to obtain those objectives. Some of the more complex code customization was for power management to enable specific sleep, suspend and wake-up states, board peripheral functionality and external device connectivity—the team had to customize 31 drivers, including the function driver to ensure the military’s TacLink modem would connect and perform properly.
- Small, fixed mechanical layout, packed with features: Without much board real estate available, RightHand hardware engineers resorted to some creative design work to maximize the circuit board space, yet achieve all the functionality requirements. First, they designed the circuit board with 12 layers and 832 components to maximize package density and minimize routing paths. They also added internal ground planes with additional layers available for optimized signal routing. This had the added benefit of improving signal integrity and reducing emissions. In addition, the engineers identified and sourced extremely small components, and stacked the primary processor and memory via package on package (PoP) layering.
- Complex power section: Crucial to the RPDA was its power section. To meet all the customer’s requirements for power management, battery charging and power sourcing, RightHand Technologies’ hardware engineers designed a complex power tree with a comprehensive power management system supervised by a dedicated microcontroller that managed the power sequencing, suspend and sleep states.
Adding a second processor to the system was a key design decision to support the 20 hour battery life requirement. While the main, high-performance OMAP applications processor exceeded all the computational and interfacing requirements, RightHand engineers decided to dedicate a microcontroller to real-time control of the power management system. Isolating these functions increased system reliability and performance. Additionally, the microcontroller monitored the health of the main processor and provided fail-safe operation by automatically resetting the system if a fault was detected.
- MIL-STD-810 certification: Throughout the design process, RightHand engineers kept MIL-STD certification in mind, and with every step, starting with component selection, sought to ensure the board would pass MIL certification requirements for vibration, shock, temperature, humidity as well as EMI emissions and susceptibility.
RightHand Technologies delivered the software and custom-designed board and met all aspects of the client’s requirements. The RPDA also obtained the MIL-STD certifications for the required sections of 810G, 461E and 464A specifications. In addition, the customer is pleased with RightHand Technologies’ work and has invited the company to bid on additional projects.