Research On Data Collection System For Pos Equipment Based On Ferroelectric Memory

As one kind of electronic equipment, POS equipment has been wildly applied to retailing, and it plays an important role in daily life consumes. Although it conveniences to peoples’lives, it makes related department monitor retailing more difficult. Because of the FRAM has many advantages, such as higher speed writing, higher endurance, lower power consumption, it is widely used in various fields, and can direct hardware replacement for EEPROM or SRAM. According to the above characteristics, this thesis put forward a designing proposal of data collector for POS equipment, which takes FRAM as storage unit to get information about receipts. The main contents are as following:(1) This thesis makes a systematic study of wording principle between POS equipment and receipt printer. By a comparative analysis of operation timing among SPP mode, EPP mode and ECP mode, taking versatile acknowledge single/ACK as trigger signal.(2) By analyzing the characteristic of print data transfers through parallel bus, data was buffered and latched to improve accuracy of data sampling. Optoelectronic isolation and power supply isolation were used to increase anti-interference ability. Through the use of ferroelectric memory to avoid the pitfalls of traditional non-volatile memory, such as finite number of write endurance, low-speed writing, etc. Adopting interrupt nest to start data dump between staging area and ferroelectric memory module, and use an idea of FSM to perform dump.(3) Having finished schematic design, PCB LAYOUT through Altium Designer 8.0. The hardware design includes minimal system, power supply unit, power supply isolation unit, signal conditioning module, FRAM module, SRAM module, RS-485 communication unit and programming download interface.(4) System program was written in the IDE which based on AVR Studio+ WinAVR. Application program design includes the function of external interrupt triggers interception of data, the function of Self-Starting process data, the data bumps function which based on the idea of state machine, TWI BUS controller, USART controller, the command system of RS-485 communication, the correction mechanism function, the function of regularly feed WDT.(5) A final experiment platform was set up. By sending a set of inductions to experiment platform, this system was verified. The experiment data and the results of contrast are given.The finding indicates that data collector for POS equipment which based on ferroelectric memory can be able to precisely collect receipts’information, and it has strong practical significance to monitor retailing.