Motorola MPC860 PowerQUICC User Manual page 793

30.2 Common SMC Settings and ConÞgurations
The following sections describe settings and conÞgurations that are common to the serial
management controllers.
30.2.1 SMC Mode Registers (SMCMRn)
The two SMC mode registers (SMCMR), shown in Figure 30-2, select the SMC mode as
well as mode-speciÞc parameters. The functions of SMCMR[8Ð15] are the same for each
protocol. SMCMR[0Ð7] vary according to the protocol selected by SMCMR[SM].
Bit 0 1
Field: UART Ñ
Transparent
GCI
Reset
R/W
Address
Table 30-1 describes SMCMR Þelds.
Bits Name
0 Ñ Reserved, should be cleared
1Ð4 CLEN Character length (UART). Number of bits in the character minus one. The total is the sum of 1 (start
bit always present) + number of data bits (5Ð14) + number of parity bits (0 or 1) + number of stop bits
(1 or 2). For example, for 8 data bits, no parity, and 1 stop bit, the total number of bits in the character
is 1 + 8 + 0 + 1 = 10. So, CLEN should be programmed to 9.
Characters range from 5Ð14 bits. If the data bit length is less than 8, the msbs of each byte in
memory are not used on transmit and are written with zeros on receive. If the length is more than 8,
the msbs of each 16-bit word are not used on transmit and are written with zeros on receive.
The character must not exceed 16 bits. For a 14-bit data length, set SL to one stop bit and disable
parity. For a 13-bit data length with parity enabled, set SL to one stop bit. Writing values 0 to 3 to
CLEN causes erratic behavior.
Character length (transparent). The values 3Ð15 specify 4Ð16 bits per character. If a character is less
than 8 bits, the msbs of the byte in buffer memory are not used on transmit and are written with zeros
on receive. If character length is more than 8 bits but less than 16, the msbs of the half-word in buffer
memory are not used on transmit and are written with zeros on receive.
Note: Using values 0Ð2 causes erratic behavior. Larger character lengths increase an SMC channelÕs
potential performance and lowers the performance impact of other channels. For instance, using 16-
rather than 8-bit characters is encouraged if 16-bit characters are acceptable in the end application.
Character length (GCI). Number of bits in the C/I and monitor channels of the SCIT channels 0 or 1.
Values 0Ð15 correspond to 1Ð16 bits. CLEN should be 13 for SCIT channel 0 or GCI (8 data bits, plus
A and E bits, plus 4 C/I bits = 14 bits). It should be 15 for the SCIT channel 1 (8 data, bits, plus A and
E bits, plus 6 C/I bits = 16 bits).
MOTOROLA
2 3 4 5
CLEN SL PEN
Ñ BS
ME Ñ
0xA82 (SMCMR1), 0xA92 (SMCMR2)
Figure 30-2. SMC Mode Registers (SMCMRn)
Table 30-1. SMCMR Field Descriptions
Chapter 30. Serial Management Controllers
Part V. The Communications Processor Module
6 7 8 9
PM Ñ
REVD
C#
0
R/W
Description
10 11 12 13 14
SM DM TEN REN
15
30-3