High Speed Coin Counter

 

Objective: The client manufactures a high speed coin counting machine that utilizes microprocessor controls that were originally designed in the 1990's and updated in the 2000's. The design used an Intel 80C198 Processor with some discreet logic to control several solenoids, relays and motors. In addition to the real time control of the various electro-mechanical components, it had an operator control panel and limited remote control functionality. Parts for the old design had become obsolete, and a new design was required.

 

The client initially tasked a different engineering design company to redesign the controller board using the Texas Instruments MSP430F5324 controller. Unfortunately the new design had multiple reliability, operational, and real time control issues that the designers were unable to fix. These issues prevented the new controller from being placed into production.

 

Result: Original Technology was tasked to review the MSP430 design and fix the issues. In reviewing the outstanding problems with the client, it was determined that the issues involved were quite extensive: inconsistent count signals, insufficient backup battery life, reliability issues with solenoid driver circuit, compatibility issues with the operation of remote control circuits, and various other software issues.

 

A thorough project review suggested that the problems involved both the hardware and the software. The prior software development effort had been done using TI's Code Composer Studio (CCS). Since CCS natively supports software development for the MSP430 processor, the same development environment was used for testing and debug. The schematic for the previous design was not done using standard tools so Cadence's Orcad software was used for schematic capture and analysis. After all hardware changes were determined, Orcad provided an easy path for Gerber file generation using an Allegro PCB layout package.

 

The coin counting issues were resolved by modifications to the analog front end of the inductive slot sensor used to detect the coins. The insufficient backup battery life was the result of some hardware issues in powering the MSP430 and the software routines used to enter low power sleep mode. Reliability issues with the solenoid driver circuit were addressed by component changes, hardware redesign, and the addition of a driver integrity circuit. Remote control was enhanced by the addition of a RS-232 serial communication protocol that provided complete operational control and monitoring. Finally the software for the controller was redesigned to provide a full featured interrupt based event driven system that would meet the demanding timing requirements.

 

With all of the design problems fixed, the focus could now be on providing an engineering package that could be used for manufacturing. Since the changes and improvements were implemented using CCS and Orcad, it was a straight forward process to produce an engineering package that was DFM (Designed For Manufacturing).

 

Original Technology’s expertise in both hardware and software proved crucial in being able to resolve all of the design problems quickly and provide the client with a fully operational controller on time and within budget.