Motorola PowerQUICC II MPC8280 Series Reference Manual page 921

Table 28-9. SMCE/SMCM Field Descriptions (continued)
Bits Name
6 TXB Tx buffer. Set when the transmit data of the last character in the buffer is written to the transmit FIFO.
Wait two character times to ensure that data is completely sent over the transmit signal.
7 RXB Rx buffer. Set when a buffer is received and its associated RxBD is closed. Set no sooner than the
middle of the last stop bit of the last character that is written to the receive buffer.
Figure 28-10 shows an example of the timing of various events in the SMCE.
Characters
Received by SMC UART
Time
RXD Line Idle
SMC UART SMCE
Events
NOTES:
1. The first RX event assumes receive buffers are 6 bytes each.
2. The second RX event position is programmable based on the MAX_IDL value.
3. The BRK event occurs after the first break character is received.
Characters
Transmitted by SMC UART
TXD Line Idle
SMC UART SMCE
Events
NOTES:
1. The TX event assumes all seven characters were put into a single buffer, and the TX event occurred when the seventh
character was written to the SMC transmit FIFO.
Figure 28-10. SMC UART Interrupts Example
28.3.12 SMC UART Controller Programming Example
The following initialization sequence assumes 9,600 baud, 8 data bits, no parity, and 1 stop
bit in a 66-MHz system. BRG1 and SMC1 are used. (The SMC transparent programming
example uses an external clock configuration; see Section 28.4.11, "SMC Transparent
NMSI Programming Example.")
1. Configure the port D pins to enable SMTXD1 and SMRXD1. Set PPARD[8,9] and
PDIRD[9]. Clear PDIRD[8] and PSORD[8,9].
2. Configure the BRG1. Write BRGC1 with 0x0001_035A. The DIV16 bit is not used
and the divider is 429 (decimal). The resulting BRG1 clock is 16× the preferred bit
rate.
3. Connect BRG1 to SMC1 using the CPM mux by clearing CMXSMR[SMC1,
SMC1CS].
4. In address 0x87FC, assign a pointer to the SMC1 parameter RAM.
MOTOROLA
Freescale Semiconductor, Inc.
10 Characters
RX
7 Characters
Chapter 28. Serial Management Controllers (SMCs)
For More Information On This Product,
Go to: www.freescale.com
Description
Line Idle
RX BRK
Line Idle
TX
SMC in UART Mode
Break
BRKE
28-21