USB2.0-based infrared data transfer system (1)

1 Introduction

As testing technology and wireless communications technology development and application of the test apparatus to miniaturization, low-power development, infrared data transfer cost is cheap, easy to use, in many small equipment has been widely used.

To avoid causing damage to the instrument interface plug, implement the test instrument and PC-wireless data transmission, reducing unnecessary cables, design a USB2.0 infrared data transfer system that has a low power, control, simple, easy to implement, transport high characteristic of dependability.

2 system hardware design

2.1 main device selection

Cypress company CY7C68013 devices include integrated microcontroller USB2.0.

It internal integration has 1 Enhanced 8051, 1 Smart USB serial interface engine, 1 x USB data transceiver, 2 UART, 3 8-bit I/O port, 16-bit address line, 8.5KBRAM and 4KBFIFO, etc. Enhanced 8051 kernel is fully compatible with standard 8051, but performance can reach standard 8051 of more than 3 times. Each instruction covers four clock cycles, working under the 48MHz crystal oscillator, single instruction cycle execution speed for 83.3ns, far faster than the standard 8051 microcontroller. EZ-USBFX2 support 3 types of interface mode, i.e. GPIF controller mode, the secondary FIFO mode and port mode. GPIF controller mode and subordinate FIFO mode and peripherals is 8-bit or 16-bit data parallel transmission needs under this system, select the serial communication port mode. Since the USB transfer of data is the baseband binary signal, and the IR transceiver for transmission of data is 3/16 NRZ, so choose the codec HSDL-7001 realization CY7C68013 device with an infrared transceiver data conversion between. In order to achieve the system's small size, choose the TFBS4652 type infrared transceiver, the transceiver is the smallest one infrared transceivers (6.8mmX2.8mmX1.6mm), quality of only 0.05g. Maximum transfer rate of up to 115.2Kbit/s (SIR), light emitting diode voltage range is 2.4 ~ 3 .6V, temperature:-25 ~ 85 ¡æ. In addition, this transceiver also has send receive enabling control end, when the system is not working, you can set this port reset low so that the transceiver will be off to reduce the system cost.

2.2 system design composition

The transmission system is mainly composed of USB2.0 interface circuits (including interface devices CY7C68013, power conversion, serial E2PROM), infrared encoding solution for the circuit and the IR transceiver 3 parts.

When the peripheral device reads the data stored in the PC machine, PC machine to send USB2.0 interface devices CY7C68013 read data request command, CY7C68013 receives a request, to communicate with a peripheral device check code through serial communication interfaces to the infrared codec HSDL-7001, then the interface devices sends out serial binary data encoded to 3/16 NRZ pulse, 3/16 NRZ data through the serial data cable transfer to an infrared transceiver, interface device turn on infrared transceiver appliances transceivers enable the infrared transceiver to infrared signal form launch 3/16 NRZ pulse data, complete the command send; when the peripherals connected to receive infrared transceiver to send 3/16 NRZ data command, sent to peripheral devices, peripheral devices receive command response send data, which is completed once from the PC to the peripheral equipment of data communication. Its specific implementation principle is shown in Figure 1.

2.3 infrared decoding circuit

Figure 2-infrared codec circuit, used mainly to infrared codec HSDL-7001, the device follows the IrDA1.0 communication protocol physical layer specifications, interface and SIR transceivers are compatible to connect with standard 16550UART, with internal or external 2 clock mode, the voltage range is 2.7 ~ 5.5V, can send/receive 1.63 μ s or 3/16 pulse data forms.

Which is 16 times the baud rate 16XCLK clock input, only used when an external crystal.

OSCOUT, OSCIN for crystal oscillator interface, low level select internal clock.

TXD pin receive CY7C68013 SCM serial port to send data via coded modulation after pulse way transmitted to IR_TXD port. Infrared-pulse data transition level pulse signal, after entering HSDL-7001 IR_RX port, internal demodulation, through the RX PIN to send data to the serial port CY7C68013 microcontroller. PIN A0, A1, A2 is used to change the baud rate selection HSDL-7001 to match the exterior with the device and PC data transfer between.

[1] [2]