The development of the off-grid electric system is based on the Intel® Atom™ Processor Z5xx Series and Intel® System Controller Hub US15W Development Kit. Although the Development Kit offers a large number of peripherals, the kit does not include wireless radio links for experimentation.





To add WiFi capabilities to the Development Kit requires the addition of both hardware (the WiFi transceiver) and software (a TCP/IP protocol stack). Green Hills Software, Inc {1} high-performance stack is one of the alternative stacks that can satisfy a socket connection for WiFi connectivity. The foundation for all networking protocols for the Green Hills family of operating systems is the GHNet TCP/IP stack. It's a full featured and high performance dual mode IPv4/IPv6 stack for embedded systems. There are options for advanced routing and security protocols. GHNet is a compact IPv4/IPv6 stack designed for minimum footprint and maximum performance. The stack is integrated and validated with INTEGRITY®, INTEGRITY-178B, velOSity™, and µ-velOSity™.

GHNet is suited for use in products including small foot print consumer devices and advanced core network equipment. It has broad Internet engineering support and has been through extensive protocol conformance and interoperability testing. Like other vendor-supported protocol stacks, it is also integrated with a broad range of networking applications, management, and security protocols.

GHNet is a true dual mode IPv4/IPv6 stack and can be configured for IPv4 only, IPv6 only, or to support both protocols simultaneously. This is an important feature since the transition from IPv4 to IPv6 is expected to take several years, perhaps more. Furthermore, the IPv6 functionality has been approved by the industry standard IPv6 READY Program, which guarantees IPv6 interoperability.

The GHNet protocol suite has a modular design and is highly configurable providing maximum size and feature scalability. When a module is not utilized, it is not just deactivated, it is removed entirely to save storage memory space in the sometimes – perhaps often - limited capacity commonly the case in embedded devices. While not the smallest stack, the completeness and existing validation for the protocol stack can make up for its size. The GHNet stack results in footprint sizes as small as 25 kilobytes for a UDP only configured stack and 41 kilobytes for a TCP enabled stack. GHNet can be configured to run in either the kernel’s address space, or in a separate partition for maximum security. It is also possible to run multiple instances of the stack in separate partitions enabling stacks to execute at multiple independent levels of security.


Like Green Hills, Wind River Systens (2) offers an integrated proprietary RTOS and a protocol stack. The tradeoff using Wind River’s TCP/IP package is the requirement to use their Real Time Operating System (RTOS). The upside is that the TCP/IP package is fully integrated and tested with VxWorks eliminating that task as part of the software development process. Wind River partners also offer a variety of TCP/IP packages including:


ACCESS Systems America Inc 


EmbVUE Inc.


Express Logic


Team F1




As often happens during development, we gained more information on data bandwidths. We are able to obtain all of the textual information from the electrical components at relatively low data rates. Information from the Outback inverter/charger is transmitted at 19.6 kbaud – a significantly lower rate than originally planned. Other sources of data (and control to the subsystem) includes a remote generator controller with a similar bandwidth requirement, water tank sensor with a bits per day data rate, and weather monitoring also at a very low data rate. With the significant reduction in the real data rate we can consider other alternatives. Recently a friend at TechBites  wrote a review of RadioCraft’s  transceiver modules. At 100kbps the RC232 series offers more than the required bandwidth. The big win for this design is a reduction in radio power requirements.

Although this system can meet its performance requirements using only a 100kbps radio communications channel, there remains the potential of using a WiFi connection. WiFi moves 100 to 1,000 times the data throughput as the lower speed radio. The Intel® System Controller Hub US15W employs a USB peripheral interface. Thus, should new peripherals or WiFi data rates become a system requirement, there remains enough processing capability to service this requirement. Of course this only deals with the data movement processing requirements and not any additional processing requirements.


What opportunities do you have in your designs to reduce cost, power, size, or cost by reducing an assumed performance requirement?



  1. Green Hills Software, Inc is an Affiliate Member of the  Intel® Embedded Alliance
  2. Wind River Systens is an Associate Member of the Intel® Embedded Alliance

Henry Davis
Roving Reporter (Intel Contractor)
Intel(r) Embedded Alliance