Embedded Linux Handheld


Foodservice Order Entry Made Easy
Linux-based Handheld Makes It Possible

Orderite provides an automated order entry system used primarily in the food service industry. Their Touchblock® hand-held order entry device allows the user to select items for order and then automatically relays the orders via modem to the distributor for those items. This reduces entry errors and saves time and money for the operator and food distributor.

Orderite recognized that while they were experts in the foodservice distribution business, they needed help with the design and development of their custom handheld device. Like many other up-and-coming companies, they had an idea of where they wanted to go but not quite sure how to get there.

When Orderite came to the PTR Group for help, they already had a generic Linux kernel up-and-running on their custom MIPS processor hardware. They also had a prototype of their application that was used for demonstrations to potential clients. Their immediate problem was that the application was missing some key functionality that required low-level software support for the custom devices and peripherals on their handheld unit. The Orderite team did not have the expertise to implement these features so they contacted The PTR Group.

One thing that we have learned over the many years of developing embedded systems is that to be successful you need to understand the “big picture”. This includes identifying the major components as well as the interfaces between the components, both physical and logical. Without this understanding, the development process turns into a fire fighting exercise where design and development is based on the daily need. This is costly in time and effort and results in a product that comes to the market late and of lesser quality.

So the first thing that PTR did for Orderite was to analyze the handheld device from both the technical side and the project management side. Our analysis took the form of a Discovery Report and proved to be extremely valuable. In our invesigation, the PTR Group uncovered several issues and potential problems that were overlooked in the current design. Based on our previous experience, we were able to recommended several solutions to each of the problems. We also generated a development plan and schedule estimate for all of the low-level software functionality that Orderite originally required. Because we invested the time up-front studying the system, our resource estimates were extremely accurate. 



The PTR Group wrote a full-feature device driver for the custom cradle interface between the handheld unit and the docking station. We also added control features for the touch screen panel, the backlight, and the LCD. During the development of these features, we also fixed numerous bugs in the platform-specific Linux software. Things such as interrupt handling and MIPS-specific I/O pin configuration. Furthermore, The PTR Group assisted the Orderite engineering team in solving problems in their software.

Our role quickly expanded from low-level software drivers to the application and then to the system as a whole. On the application level, The PTR Group rapidly developed a special version of the application that was tailored to one of the future customers. The functionality and implementation were so well received that many of them were rolled into the baseline of their official product offering.

Two of the issues we identified in our Discovery Report were the lack of field update capability and the shortcomings of Orderite’s custom communications protocol. The Orderite staff agreed with our assessment. They then tasked us with solving both problems for them in the shortest possible time with the least impact on the current software base. The PTR Group met both these goals by leveraging the well known YMODEM protocol into a single application that could function as both the client and the server, in both a graphical mode and a text based mode. The software alllowed Orderite to automatically update the handhelds in the field with a simple call to their control center.

When time came to develop the next revision of the hardware, Orderite came straight to us and said that they wanted us to take over all responsiblity for all of the software assocaited with the device. One of the major components that was added was a new touch screen controller, the ADS7846. To support this new chip we wrote a new device driver as well as adding support to the graphics library for this new chipset. Another major component on the new revision of the hardware that we supported was the SiS2433 modem chipset. Like the other new components, support for this device involved modifying several pieces of software ranging from the low-level serial device drivers all the way up to the application itself.

Key Project Highlights

  • Developing device drivers for custom hardware, including modem chipsets, touch screen controllers, and cradle interface.
  • Fixing bugs and configuring the Linux kernel
  • Rapid prototyping new applications for marketing demonstrations and future deployment.
  • Systems engineering and architecture.

    The PTR Group is given full responsibility for the design and development of all software on the Orderite Touchblock handheld device. We want The PTR Group to be our Touchblock guys. – Doug Dillard, President, Orderite, Inc.