Freescale Semiconductor PowerQUICC MPC885 Reference Manual page 736

SCC Asynchronous HDLC Mode and IrDA
7. Program RFCR and TFCR.
8. Write MRBLR with the maximum Rx buffer size.
9. Write C_MASK and C_PRES with the standard values.
10. Clear the Zero register.
11. Program RFTHR to the number of frames to be received before generating an interrupt.
12. Program the control character tables, TXCTL_TBL and RXCTL_TBL.
13. Initialize all RxBDs.
14. Initialize all TxBDs.
15. Clear SCCE by writing 0xFFFF to it.
16. Program SCCM to enable all preferred interrupts.
17. Program GSMR_H.
18. Program GSMR_L to asynchronous HDLC mode, but do not turn on the transmitter or receiver.
19. Set the PSMR appropriately. See
(PSMR)."
20. Enable the transmitter and receiver in GSMR_L.
25.18 IrDA Encoder/Decoder (SCC2 Only)
The IrDA (Infrared Data Association) data link protocol can be run on any SCC. However, SCC2 includes
additional hardware to support the encoding/decoding required by the IrDA physical layer.
IrDA defines a family of specifications for interconnecting computers and peripherals using a directed
half-duplex serial infrared communications medium. The IrDA data link layer protocol is based on a
preexisting standard asynchronous HDLC protocol. Figure 25-9. shows a serial infrared (SIR) link.
MPC885
UART
(SCC2)
The signal between the UART and the encoder/decoder module is a bit stream of pulses in a frame
comprised of a start bit, 8 data bits, no parity bit, and ending with a stop bit, as shown in Figure 25-10.(a).
The signal between the encoder/decoder module and infrared (IR) transducer module is shown in
Figure 25-10.(b). The electrical pulses between the IR transmit encoder and the output driver and LED are
3
/ of a bit period in duration (or for the slower bit rates, as short as
16
25-14
Section 25.13.3, "Asynchronous HDLC Mode Register
Encoder/Decoder
Module
TXD IR Transmit
Encoder
RXD IR Receive
Decoder
Figure 25-9. Serial Infrared (SIR) Link
MPC885 PowerQUICC Family Reference Manual, Rev. 2
IR Transducer
Module
Output Driver &
IR Out
LED
Detector &
IR In
Receiver
3
/ of the bit period for 115.2 Kbps).
16
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