PB03 Resources - IrDA Interface

The PB03 provides a fast infrared transceiver, courtesy of a TFDU6102 device (from Vishay Semiconductors). This device is compliant with the IrDA® (Infrared Data Association) standard for fast infrared data communications (FIR), and can also be used for remote control. The former allows you to place a device possessing an IrDA port next to the NB2DSK01 and effect wireless communications between the two.

Figure 1. IrDA interface.

• IrDA communications – offering slow infrared (SIR; 2.4kbit/s to 115.2kbit/s) medium infrared (MIR; 576kbit/s to 1152kbit/s) and fast infrared (FIR; 4Mbit/s) modes, with a link distance greater than 1m (provided clear line-of-sight is kept between the two IrDA ports).

• Remote Control – supporting transmission/reception of RC codes (encoded using protocols such as NEC, or Philips RC5) that have been modulated using a carrier wave up to a frequency of 2MHz. The interface supports a range of more than 8m (typically 22m).

 
The TFDU6102 consists of a PIN photodiode for reception, an Infrared Emitting Diode (IRED) for transmission, and control logic. Primary power for the device comes from the PB03's 3.3V supply, with the anode of the IRED connected to the board's 5V supply through a 2Ω resistance.

After power-on the device is set, by default, to operate in low-speed (SIR) mode. The mode of the device can be explicitly or dynamically controlled:

• Explicit mode control – control is performed using the IRDA_MODE signal from the FPGA design, which is wired to the device's Mode pin. Take this signal High to place the device in high-speed (MIR and FIR) mode. Keep this signal Low to remain in low-speed (SIR) mode.

• Dynamic mode control – control is performed using the IRDA_SD and IRDA_TXD signals from the FPGA design, which are wired to the device's SD and TXD pins respectively. Taking the IRDA_SD signal High places the device in shutdown mode. On the falling edge of this signal the TXD input is sampled. If IRDA_TXD is Low, the device remains in low-speed (SIR) mode. If High, the device is placed in high-speed (MIR and FIR) mode.

Serial data from a processor in the FPGA design is sent to the device on the IRDA_TXD line. Transmission is only possible provided IRDA_SD is Low. The data is ultimately converted into infrared waves, via the IRED, and sent out to an IrDA transceiver in an external, neighboring device. The additional signal IRDA_TXD_LED (active High) is used to light an associated Red LED to indicate transmission.

Transmitted infrared data from a neighboring device is detected by the PIN photodiode and converted into a voltage signal. The subsequently conditioned data is sent serially to the processor in the FPGA design via the IRDA_RXD line. The additional signal IRDA_RXD_LED (active High) is used to light an associated Green LED to indicate reception.
 

Location on Board

The infrared transceiver (designated U1_IR) is located on the component side of the board, in-between the Ethernet and USB ports.

The 'RxD' and 'TxD' LEDs (designated LED5 and LED6) are also located on the component side of the board, to the right and left of the infrared transceiver respectively.

Schematic Reference

The IrDA interface circuitry can be found on sheet IrDA_TFDU6102.SchDoc (entitled IrDA (Infra-red) LED) of the peripheral board schematics.

Design Interface Component

Table 1 summarizes the available design interface component that can be placed from the FPGA PB03 Port-Plugin.IntLib to access the IrDA interface.

Further Device Information

For more information on the TFDU6102 device, refer to the datasheet (tfdu6102.pdf) available at www.vishay.com.