Memory Map/Register Definition
MCF548x Reference Manual, Rev. 3
Freescale Semiconductor 26-27

26.3.3.21 Rx and Tx FIFO Counter Register (PSCRFCNTn, PSCTFCNTn)

This register applies to all modes.

26.3.3.22 Rx and Tx FIFO Data Register (PSCRFDRn, PSCTFDRn)

These registers provide access to the internal Rx and Tx FIFOs.

Table 26-27. PSCIRFDRn Field Descriptions

Bits Name Description
7–4 Reserved, should be cleared.
3–0 F_FDIV Applies only in FIR mode; in all other modes, this field is reserved.
In FIR mode, this field signifies clock divide ratio.
The bit frequency is derived by the following equation.

Eqn. 26-2

This bit frequency should be 8 MHz. In order to receive the minimum pulse width described in the
IrDA spec, (F_FDIV + 1) should be larger than or equal to 4. shows several frequency selection.
See Table 26-28., “Frequency Selection in FIR Mode

Table 26-28. Frequency Selection in FIR Mode

F_FDIV[3:0] Frequency of bit_clk [MHz]
332.0
440.0
548.0
656.0
... ...
1514131211109876543210
R0000000 CNT
W
Reset0000000000000000
Reg
Addr
MBAR + 0x8658 (PSCRFCNT0); 0x8758 (PSCRFCNT1); 0x8858 (PSCRFCNT2); 0x8958 (PSCRFCNT3)
and MBAR + 0x865C (PSCTFCNT0); 0x875C (PSCTFCNT1); 0x885C (PSCTFCNT2); 0x895C (PSCTFCNT3)

Figure 26-18. RxFIFO (PSCRFCNTn) and TxFIFO (PSCTFCNTn) Counter Register

Table 26-29. PSCRFCNTn and PSCTFCNTn Field Descriptions

Bits Name Description
15-9 Reserved, should be cleared.
8–0 CNT Number of bytes in the FIFO
fbit
fbit_clk
F_FDIV 1+
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