Vault 7: Projects
This publication series is about specific projects related to the Vault 7 main publication.
dsPIC33/PIC24 Family Reference Manual
DS70000582E-page 38 2009-2013 Microchip Technology Inc.
Figure 13-3: IrDA
®
Encode Scheme for ‘0’ Bit Data with Respect to 16x Baud Clock
13.2.3 IrDA DECODER FUNCTION
The decoder works by taking the serial data from the UxRX pin and replacing it with the decoded
data stream. The stream is decoded based on falling edge detection of the UxRX input.
Each falling edge of UxRX causes the decoded data to be driven low for 16 periods of the
16x baud clock. If, by the time the 16 periods expire, another falling edge is detected, the
decoded data remains low for another 16 periods. If no falling edge was detected, the decoded
data is driven high.
Note that the data stream into the device is shifted anywhere from 7 to 8 periods of the 16x baud
clock from the actual message source. The one clock uncertainty is due to the clock edge
resolution (see Figure 13-4 for details).
Figure 13-4: IrDA
®
Decoding Scheme
13.2.4 IrDA RECEIVE POLARITY
The input of the IrDA signal can have an inverted polarity. The same logic is able to decode the
signal train, but in this case, the decoded data stream is shifted from 10 to 11 periods of the
16x baud clock from the original message source. Again, the one clock uncertainty is due to the
clock edge resolution (see Figure 13-5 for details).
Figure 13-5: Inverted Polarity Decoding Results
Start ofStart of
0 Transmit bit
16x Baud Clock
UxTX Data
UxTX
8th Period 11th Period
16 Periods 16 Periods 16 Periods 16 Periods 16 Periods
Start BRG
T
IRDEL
Before IrDA
®
Encoder
UxRX
Decoded Data
(Transmitting Device)
16 Periods 16 Periods 16 Periods 16 Periods 16 Periods
Start BRG TIRDELI
Before IrDA
®
Encoder
UxRX
Decoded Data
(Transmitting Device)
Protego_Release_01_05-Related-OEM-Documentation-PIC24FJ64GA004-Universal_Asynchronous_Receiver_Transmitter.pdf