Vault 7: Projects
This publication series is about specific projects related to the Vault 7 main publication.
2009-2013 Microchip Technology Inc. DS70000582E-page 37
UART
13.0 INFRARED SUPPORT
The UART module provides two types of infrared UART support: one is the IrDA
®
clock output
to support the external IrDA encoder and decoder devices (legacy module support), and the
other is the full implementation of the IrDA encoder and decoder.
13.1 External IrDA Support – IrDA Clock Output
To support external IrDA encoder and decoder devices, the BCLKx pin can be configured to gen-
erate the 16x baud clock. When UEN<1:0> = 11, the BCLKx pin outputs the 16x baud clock if
the UART module is enabled; this pin can be used to support the IrDA codec chip.
13.2 Built-in IrDA Encoder and Decoder
The UART has full implementation of the IrDA encoder and decoder. The built-in IrDA encoder
and decoder functionality is enabled using the IREN bit (UxMODE<12>). When enabled
(IREN = 1), the receive pin (UxRX) acts as an input from the infrared receiver. The transmit pin
(UxTX) acts as an output to the infrared transmitter.
13.2.1 IrDA ENCODER FUNCTION
The encoder works by taking the serial data from the UART and replacing it. Transmit bit data of
1 becomes encoded as 0 for the entire 16 periods of the 16x baud clock. Transmit bit data of
0 becomes encoded as 0 for the first 7 periods of the 16x baud clock, as 1 for the next
3 periods and as 0 for the remaining 6 periods. See Figure 13-1 and Figure 13-3 for details.
13.2.2 TRANSMIT POLARITY
The transmit polarity is selected using the UTXINV bit (UxSTA<14>). When UTXINV = 0, the Idle
state of the UxTX line is 0 (see Figure 13-1). When UTXINV = 1, the Idle state of the UxTX line
is 1 (see Figure 13-2).
Figure 13-1: IrDA
®
Encode Scheme
Figure 13-2: IrDA
®
Encode Scheme for ‘0’ Bit Data
Note: This feature is available only in Standard Speed mode (BRGH = 0) with a baud rate
above 1200 baud.
Note: Some devices may have a 16x baud clock output (BCLKx) Idle state as a logic high.
UxTX Data
UxTX
UxTX Data
UxTX
Protego_Release_01_05-Related-OEM-Documentation-PIC24FJ64GA004-Universal_Asynchronous_Receiver_Transmitter.pdf