Smc Function Code Registers (Rfcr/Tfcr) - Freescale Semiconductor MPC850 User Manual

Table 30-2. SMC UART and Transparent Parameter RAM Memory Map (Continued)
1
Offset Name Width
0x14 — Word
0x18 TSTATE Word
0x1C — Word
0x20 TBPTR Hword TxBD pointer. Points to the next BD for each SMC channel the transmitter transfers data
0x22 — Hword Tx internal byte count.
0x24 — Word
0x28 — Hword First half-word of protocol-specific area.
0x32 — Hword Last half-word of protocol-specific area.
1
From SMC base address. SMC base = IMMR + 3E80 (SMC1), 3F80 (SMC2).
2
Not accessed for normal operation. May hold helpful information for experienced users and for debugging.
To extract data from a partially full Rx buffer, issue a
Certain parameter RAM values must be initialized before the SMC is enabled. Other values
are initialized or written by the CP. Once values are initialized, software typically does not
need to update them because activity centers mostly around Tx and Rx BDs rather than
parameter RAM. However, note the following:
• Parameter RAM can be read at any time.
• Values that pertain to the SMC transmitter can be written only if SMCMR[TEN] is
zero or between the
• Values for the SMC receiver can be written only when SMCMR[REN] is zero, or, if
the receiver is previously enabled, after an
but before the

30.2.3.1 SMC Function Code Registers (RFCR/TFCR)

Each SMC channel has two function code registers—one for receiving (RFCRn) and one
for transmitting (TFCRn). The function code entry contains the value to appear on the
function code pins AT[1–3] when the associated SDMA channel accesses memory. The
FCRs also control byte-ordering. See Figure 30-4.
2
Rx temp. Can be used only by the CP.
Tx internal state. Can be used only by the CP.
2
Tx internal data pointer.
the buffer to be accessed.
from when it is in idle state or to the current BD during frame transmission. After reset or
when the end of the table is reached, the CP initializes TBPTR to the TBASE value.
Most applications never need to write TBPTR, but it can be written when the transmitter
is disabled or when no transmit buffer is in use. For instance, after a
GRACEFUL STOP TRANSMIT
2
A down-count value initialized with the TxBD data length and
decremented with every byte the SDMA channels read.
2
Tx temp. Can be used only by the CP.
STOP TRANSMIT
command is issued and REN is set.
CLOSE RXBD
Chapter 30. Serial Management Controllers (SMCs)
Common SMC Settings and Configurations
Description
Updated by the SDMA channels to show the next address in
command is issued and the frame completes its transmission.
CLOSE RXBD
and
RESTART TRANSMIT
ENTER HUNT MODE
or
STOP TRANSMIT
command.
commands.
command is issued