The MCP2122 is a stand-alone IrDA standard encoder/ decoder device that is pinout-compatible with the Agilent HSDL-7000 encoder/decoder.
The MCP2122 has two interfaces: the host UART interface and the IR interface. The host UART interfaces to the UART of the Host Controller. The Host Controller is the device in the embedded system that transmits and receives the data. The IR interface connects to an infrared (IR) optical transceiver circuit that converts electrical pulses into IR light (encode) and converts IR light into electrical pulses (decode). This IR optical transceiver circuit could be either a standard infrared optical transceiver or it could be implemented with discrete components.
When the Host Controller transmits the UART format data, the MCP2122 receives this UART data and encodes (modulates) it bit by bit. This encoded data is then output as electrical pulses to the IR transceiver. The IR transceiver will then convert these electrical pulses to IR light pulses.
The IR transceiver also receives IR light pulses (data), which are outputted as electrical pulses. The MCP2122 decodes (demodulates) these electrical pulses, with the data then being transmitted by the MCP2122 UART. This modulation/demodulation method is performed in accordance with the IrDA standard.
The MCP2122 is a low-cost infrared encoder/decoder. The baud rate is the same for the host UART and IR interfaces and is determined by the frequency of the 16XCLK signal, with a maximum baud rate of 115.2 Kbaud.
The MCP2122 is made up of these functional modules:
- Clock Driver (16XCLK)
- Reset
- IR Encoder/Decoder - IrDA Standard Encoder - IrDA Standard Decoder
The 16XCLK circuit allows a clock input to provide the device clock.
The Reset circuit supports an external reset signal.
The IR Encoder logic takes a data bit and converts it to the IrDA standard signal according to the IrDA standard Physical Layer specification, while the IR Decoder logic takes the IrDA standard signal and converts it to 8-bit data bytes.
MICROCHIP MCP2122T-E/SN