Intel 83C196NP Microcontroller Application Brief: Bar Code Scanner

(2307) Intel 83C196NP Microcontroller Application Brief: Bar Code Scanner

Intel 83C196NP Microcontroller
Application Brief: Bar Code Scanner

The grocery business gets tougher all the time. Superstores with everything from bakeries to pharmacies are driving out mom and pop corner groceries. Enormous stores with thousands of products make it impossible for store personnel to be familiar with the location and price of every product, and the escalating overhead makes profit margins slimmer than ever. This was the competitive situation a large West Coast grocery chain faced at the end of its worst year ever. The grocery chain decided it had to automate its stores or go bankrupt.

An MIS task force decided to outfit the chain's 95 stores with handheld bar code scanners. Handheld devices offered more versatility than stationary bar code scanners at the checkstand. They could not only be used for checkout but also in the aisles to stock and price merchandise, and on the loading dock to verify incoming shipments. Hopefully, the new units would give employees and store managers a firmer grasp on how much of each product they were selling each day, make sure that hot products were amply stocked, improve customer service by speeding checkout, and eliminate error.

The engineers designing the scanner set forth a series of requirements. The handheld scanner had to be small and lightweight, so store personnel could wear it in a holster or hold it for an entire workday. It had to be fast, so it could process data as fast as the clerk could swipe it across the bar code. They wanted to incorporate a keyboard, so stocking clerks could enter information about inventory. Sound capability was necessary so the unit could beep to indicate scan status. And it had to have a serial port so the units could be connected to PCs at the end of every day and the data uploaded, stored and later analyzed. Of course, they wanted all this at the lowest possible price.

Designers decided that a microcontroller would be perfect for the job of positioning the laser, receiving the reflection, translating the bar code into a number, and storing it in memory. After a thorough search for the perfect bar scanner "brain," the team selected the Intel 83C196NP embedded controller for the heart of their design because it contained the right features in a smaller package. For starters, there's a new peripheral called the Chip Select Unit, which eliminates glue logic to external interface chips. This allowed designers to reduce the overall chip count on-board. The de-multiplexed bus of the 196 controller also eliminates up to two latches, another parts saving. In addition to eliminating parts, the built-in functionality of the 196 controller simplifies design by reducing the amount of interface logic. It also shortens the development process, since much of the design work is already done, and lowers manufacturing costs. All this in an extremely compact, 100-lead SQFP (or QFP) package.

There were other things they saw in the 196 that they didn't see in other microcontrollers. A feature called the Event Processor Array (EPA) provided extremely high resolution (160 ns) for dealing with faster input and output. This, together, with a clock speed of 16 MHz (at 3.3 volt operation) meant that clerks would never be left waiting for the scanner to catch up. The 196 controller also has a pulse width modulator (PWM) they could use for generating a range of beeping sounds, needed to quickly indicate scan status. The PWM unit ran with no CPU overhead. Finally, the 196 controller has 4 Kbytes of on-chip ROM that could be used to store software routines, again, eliminating the need for external memory chips. Other microcontrollers with this much on-chip functionality were power hungry ; not the 196. It requires a mere 3.3 volts thus can run longer and on batteries.

Thanks to the on-chip peripherals and simplified design process made possible by the Intel 196 controller, the team finished the unit ahead of schedule. They also ended up with more features and less weight than they had anticipated.

The handheld scanners have been in place for only a few months, but already the store is seeing savings. Stockroom clerks "shoot" merchandise as it comes in the door, ascertaining then and there if the amount received matches the amount ordered. Management uses the more accurate stock data to better control in-store theft. In the aisles, the stocking clerks use the devices to change pricing and check inventory, eliminating hours of manual labor spent counting and re-shelving product. These people now use their extra time serving customers rather than handling and managing inventory. At the checkout counter, there's much less error in ringing up prices, not to mention less fatigue and carpal stress, since clerks no longer have to work a cash register keyboard.

From management's perspective, the scanning system has provided a wealth of data on the movement of goods through their stores, giving them a window into which products sell better at which stores, at which prices. Being able to adjust stocking levels to buying patterns and run specials at stores where merchandise is not moving has saved them thousands of dollars in revenue.

Best of all, customers are happier, since shelf prices are always marked and accurate, checkout is faster, and store personnel are friendly and available to help. The end result: more customers, more business, higher revenues. And that's what it's all about.

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