Welcome to the training module on Handheld Point of Sale Terminal . This training module will introduce a reference design for handheld POS Terminal and recommend core components suitable for this applications.
A Point-of-Sale terminal is a common part of today’s retail industry that customers often see at checkout. They combine cash register functions with special purpose functions such as credit authorization, sales analysis, inventory update, automatic calculations like sales tax, and local reports on inventory or sales. Traditionally, a typical POS terminal is PC based, including a keyboard for data entry, a display panel for the price, a cash drawer, and a printer for providing receipts and reports. This type is stationary POS termainal. A POS terminal can be networked to other terminals, and to a server in the back room or at another location. For mobile or handheld POS terminal, it can be either wirelessly linked to the main system or process data in batches when physically connected to a back end data center.
With the rapid rise of wireless technology, the handheld POS terminals is a handsets that can be carried around retail departments, entertainment, and dining environments, adding flexibility to transactions. These are small, light-weight, battery powered and have integrate functions such as a display, card reader, keypad and are printer capable of transacting a sales event and performing a secure remote electronic payment. Handheld POS terminals enable merchants to process credit and debit card payments conveniently and securely. The significant success of the hardware platform of handheld POS terminal makes the similar solutions popular in many applications. These solutions eliminate or simplify the financial safety design in handheld POS terminals and enhance the practical management functions such as VIP card management, order placement in restaurants, and warehouse management.
Before designing a handheld POS terminal, you have to know what functions the POS terminal should have. Here we list some typical features you may find in the various commercial POS products. Not every POS terminal have all these features. Some will have features not listed here. The basic functions that a normal POS terminal must have include credit/debit card reading, access to bank systems, receipt printing, display, keypad input, data export and data protection. A POS terminal can help monitor transactions by employee by requiring a check-in and check-out procedure. Most POS terminals feature inventory control, multiple price points for same products, sales tax calculations, invoicing, and suspend and hold an uncompleted transaction. Networking capability makes the POS terminal communicate with the central database system. Moreover, all POS systems should provide some level of security.
To support the basic functions, firstly a handheld POS terminal must have a micro card reader that is compliant with credit/debit card standards. Secondly the GPRS/CDMA modules used for wireless communication should be able to access bank systems reliably and safely. Thirdly, a micro thermal printer can be a best choice for the print device used on a handheld POS terminal because of its small size, low noise and high printing speed. Fourthly, a TFT LCD display indeed is doing best in terms of the color display quality. We need to make our decision based on the requirements of the application. Fifthly, although the mature touch screen technology has made the use of handheld POS terminal much easier, it is recommended to retain the traditional keypads in case of the malfunction of touch screens. Sixthly, we’d better use a small-sized interface such as mini USB or Ethernet for the export of transaction data. Seventhly, a security supervisor IC should be dedicatedly designed to protect the classified financial information stored in the device from being stolen by criminals. Lastly, a powerful MCU with low power consumption is necessary to drive those components to work properly. Nevertheless, all of these are just the basic requirements of a handheld POS terminal
The microcontroller is used for processing the payment transactions and wireless communication, managing the menu system, interpreting keyboard and card reader input, sending receipt print command, handling data storage, and updating the LCD screen. POS terminals also require to comply with highest data security and integrity requirements, and be certified by Payment Card Industry and EMV organizations. As the POS terminal requires fast transaction, high speed CPU clock of the MCU is needed. Meanwhile, the POS terminal is portable type, so the MCU should be low power consumption to extend battery lifetime. Here we select a series of low power 32-bit ARM cortex-M3 microcontrollers.
The STM32F105xx and STM32F107xx connectivity line family incorporates the high performance ARM® Cortex™-M3 32-bit RISC core operating at a 72 MHz frequency, high speed embedded memories (Flash memory up to 256 Kbytes and SRAM up to 64 Kbytes), and an extensive range of enhanced I/Os and peripherals connected to two APB buses. All devices offer two 12-bit ADCs, four general-purpose 16-bit timers plus a PWM timer, as well as standard and advanced communication interfaces
Security requirements for POS terminal are defined by a number of national, international, and industry-specific standards: FIPS-140 (Federal Information Processing Standards) is used by US Federal organizations when specifying cryptography-based security systems for the protection of sensitive data, and is widely used for other applications; EMV Co (Europay, MasterCard, and Visa), PCI (Payment Card Industry); and the German ZKA (Zentraler Kreditausschuss) define standards for payment and banking applications. The security supervisor devices add additional features including watchdog and early power-fail Warning (power-fail In/power-fail out – PFI/PFO, push-button reset and battery monitoring). Microprocessor supervisors with a switchover function preserve SRAM data in the absence of system power by automatically switching to battery backup when system power fails. A Chip-Enable Gate automatically write-protects the SRAM when Vcc begins to fall. The security supervisor also features intrusion detection to enable the POS terminal to meet physical and environmental intrusion monitoring requirements as mandated by various standards.
The STM140x series of pin- and plug-in compatible ultra-low-current security supervisors integrate all functions for detecting physical and environmental intrusion required by the major security standards. The supervisor satisfies the performance and board-space requirements of POS terminal applications, while enabling them to achieve formal security certification for physical and environmental tamper detection. The chip continuously monitors physical tamper units and switches, primary and battery-backup supply voltages, and ambient temperature, raising an alarm if it detects any attempt at intrusion.
Nowadays, more and more POS terminals use GPRS / CDMA wireless technologies to make online transactions. GPRS / CDMA provides rapid speed. For example, the authorization process takes only a few seconds. It also allows information to be sent while the operator is mobile, making the terminal ideal for dispatching applications. We select a series of GPRS / CDMA modules for your considerations.
Like other applications, you need other components to complete the design. The FLASH memory is used to store program, and SRAM for storing transaction data temporarily. The boost DC/DC converter and buck DC/DC converter are used for charging li-ion battery. The embedded printer is used for receipt printer.
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Handheld Point of Sale Terminal
Handheld Point of Sale Terminal
Introduction <ul><li>Purpose </li></ul><ul><ul><li>To introduce a reference design for handheld POS Terminal and recommend core components suitable for this applications. </li></ul></ul><ul><li>Outline </li></ul><ul><ul><li>Point of Sale system overview </li></ul></ul><ul><ul><li>Handheld POS terminal features </li></ul></ul><ul><ul><li>Block diagram </li></ul></ul><ul><ul><li>Core component selection guide </li></ul></ul><ul><li>Content </li></ul><ul><ul><li>13 pages </li></ul></ul>
Point-of-Sale System <ul><li>A Point of Sale (POS) terminal is a device that allows the transfer of funds electronically. </li></ul><ul><li>POS system enables for credit authorization, sales analysis, inventory update, etc. </li></ul><ul><li>A POS terminal can be networked to other terminals and to a server. </li></ul><ul><ul><li>The connection can be wireless. </li></ul></ul><ul><li>There are two main categories of POS terminals. </li></ul><ul><ul><li>Stationary POS terminals </li></ul></ul><ul><ul><li>Mobile or Handheld POS terminals </li></ul></ul>Stationary POS Terminals Handheld POS Terminals
Why Handheld POS Terminals so Popular? <ul><li>Convenient </li></ul><ul><ul><li>Fast </li></ul></ul><ul><ul><li>Seamless integration into merchant networks </li></ul></ul><ul><ul><li>Embedded security and device management </li></ul></ul><ul><ul><li>Cash replacement niches (mobility, vending machines) </li></ul></ul><ul><li>Low cost </li></ul><ul><ul><li>Payment devices </li></ul></ul><ul><ul><li>Communication </li></ul></ul><ul><ul><li>Deployment </li></ul></ul><ul><ul><li>Short application development </li></ul></ul><ul><li>High growth area </li></ul><ul><ul><li>Available for all terminal types </li></ul></ul><ul><ul><li>Permits use in non fixed locations </li></ul></ul>
Standard POS Features <ul><li>Credit/Debit reading </li></ul><ul><li>Networking/Multiple stations </li></ul><ul><ul><li>Access to back system </li></ul></ul><ul><li>Keypad input </li></ul><ul><li>Receipt printing </li></ul><ul><ul><li>Invoicing </li></ul></ul><ul><li>Display </li></ul><ul><li>Data export and protection </li></ul><ul><ul><li>Inventory control </li></ul></ul><ul><ul><li>Suspend/Resume transactions </li></ul></ul><ul><ul><li>Sales tax calculations </li></ul></ul><ul><ul><li>Ordering and receiving </li></ul></ul><ul><ul><li>Multiple price levels for same product </li></ul></ul><ul><li>Security </li></ul><ul><ul><li>Check-in/Check-out </li></ul></ul>Keypad Display Receipt Printer Card Reader Wireless connection
Microcontroller Selection Guide 32-bit ARM Cortex-M3 MCUs with USB-OTG Manufacturer Part Number Frequency (Max) GPIO (Max) RAM (KB) Flash (KB) Power (Active Mode) Power (Standby Mode) NXP LPC175x 100 52 Up to 64 Up to 512 42mA 40nA NXP LPC176x 100 70 Up to 64 Up to 512 42mA 134nA TI Stellaris® 5000 80 Up to 72 Up to 64 Up to 256 0.56 180 TI Stellaris® 9000 80 Up to 65 Up to 96 Up to 256 0.56 N/A ST STM32F105R8 72 51 20 64 48mA 3uA ST STM32F105RB 72 51 32 128 48mA 3uA ST STM32F105RC 72 51 64 256 48mA 3uA ST STM32F105V8 72 80 20 64 48mA 3uA ST STM32F105VB 72 80 32 128 48mA 3uA ST STM32F105VC 72 80 64 256 48mA 3uA ST STM32F107RB 72 51 48 128 48mA 3uA ST STM32F107RC 72 51 64 256 48mA 3uA ST STM32F107VB 72 80 48 128 48mA 3uA ST STM32F107VC 72 80 64 256 48mA 3uA
STM32F105/107 32-bit ARM Cortex MUCs <ul><li>72MHz maximum CPU Clock </li></ul><ul><li>Up to 256 KB Flash & Up to 64 KB SRAM </li></ul><ul><li>Clock, reset and supply management </li></ul><ul><li>Low power consumption </li></ul><ul><li>2 x 12-bit, 1 µ s ADCs (16 channels) </li></ul><ul><li>2 x 12-bit DACs </li></ul><ul><li>12-channel DMA controller </li></ul><ul><li>Up to 14 communication interfaces </li></ul><ul><ul><li>2xI2C, 5 USARTs, 3 SPIs, 2 CANs, USB/host/OTG, 10/100 Ethernet </li></ul></ul>
Security Supervisor Selection Guide Manufacturer Part Number FIPS-140 Tamper Detect Inputs RST Threshold (VPFD) Manual Reset Temperature Alarm ST STM1403ASMQ6F level 3+ 4 2.925V Yes No ST STM1403ATNQ6F level 3+ 4 3.075V Yes No ST STM1403ATOQ6F level 3+ 4 3.075V Yes No ST STM1403CSMQ6F level 3+ 4 2.925V Yes No ST STM1403CSNQ6F level 3+ 4 2.925V Yes No ST STM1403CTNQ6F level 3+ 4 3.075V Yes No ST STM1404CSMJQ6F level 3+ 4 2.925V Yes Yes ST STM1404CSNIQ6F level 3+ 4 2.925V Yes Yes ST STM1404CSNJQ6F level 3+ 4 2.925V Yes Yes ST STM1404CTMJQ6F level 3+ 4 3.075V Yes Yes ST STM1404CTNJQ6F level 3+ 4 3.075V Yes Yes ST STM1404CTOCQ6F level 3+ 4 3.075V Yes Yes
STM140x FIPS-140 Security Supervisor Family <ul><li>Support FIPS-140 security level 3+ </li></ul><ul><ul><li>4 high-impedance physical tamper inputs </li></ul></ul><ul><ul><li>Over/under operating voltage detector </li></ul></ul><ul><ul><li>Security alarm on tamper detection </li></ul></ul><ul><ul><li>Over/under operating temperature detector </li></ul></ul><ul><li>Supervisory functions </li></ul><ul><ul><li>Automatic battery switchover </li></ul></ul><ul><ul><li>RST output </li></ul></ul><ul><ul><li>Manual reset input </li></ul></ul><ul><ul><li>Power-fail comparator </li></ul></ul><ul><li>Battery low voltage detector </li></ul><ul><li>Low battery supply current </li></ul>
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