CHAPTER 8 UART
Preliminary User’s Manual S15543EJ1V0UM 417
8.3.6 UARTDLM (UART Divisor Latch MSB Register)This register is used to set the divisor (division rate) for the baud rate generator. The data in this register and thelower 8-bit data in UARTDLL register are together handled as 16-bit data.
Bits Field R/W Default Description
31:8 Reserved R/W 0 Hardwired to 0.
7:0 DIVLSB R/W - UART divisor latch (see Table 8-1):
Only accessed when DLAB = 1 in UARTLCR
Table 8-1. Correspondence between Baud Rates and Divisors
Baud Rate UART Source Clock Frequency
[bps] 18.432 MHz
(Use External Clock)
33.000 MHz
(CPU Clock = 66 MHz)
50.000 MHz
(CPU Clock = 100 MHz)
Divisor Error Divisor Error Divisor Error
50 23040 (5A00H) 0 41250 (A122H) >1 % 62500 (F424H) 0
75 15360 (3C00H) 0 27500 (6B6CH) >1 % 41667 (A2C3H) >1 %
110 10473 (28E9H) 0 18750 (493EH) >1 % 28409 (6EF9H) >1 %
134.5 8565 (2175H) 0 15335 (3BE7H) >1 % 23234 (5AC2H) >1 %
150 7680 (1E00H) 0 13750 (35B6H) >1 % 20833 (5161H) >1 %
300 3840 (F00H) 0 6875 (1ADBH) >1 % 10417 (28B1H) >1 %
600 1920 (780H) 0 3438 (D6EH) >1 % 5208 (1458H) >1 %
1200 920 (398H) 0 1719 (6B7H) >1 % 2604 (A2CH) >1 %
1800 640 (280H) 0 1146 (47AH) >1 % 1736 (6C8H) >1 %
2000 573 (23DH) 0 1031 (407H) >1 % 1562 (61AH) >1 %
2400 480 (1E0H) 0 859 (35BH) >1 % 1302 (516H) >1 %
3600 320 (140H) 0 573 (23DH) >1 % 868 (364H) >1 %
4800 240 (F0H) 0 430 (1AEH) >1 % 651 (28BH) >1 %
7200 160 (A0H) 0 286 (11EH) >1 % 434 (1B2H) >1 %
9600 120 (78H) 0 215 (D7H) >1 % 326 (146H) >1 %
19200 60 (3CH) 0 107 (6BH) >1 % 163 (A 3H) >1 %
38400 30 (1EH) 0 54 (36H) >1 % 81 (51H) >1 %
56000 21 (15H) 2.04 % 37 (25H) >1 % 56 (38H) >1 %
128000 9 (9H) 0 16 (10H) >1 % 24 (18H) 1.69 %
144000 8 (8H) 0 14 (EH) 2.25 % 22 (16H) 1.38 %
192000 6 (6H) 0 11 (BH) 2.41 % 16 (10H) 1.69 %
230400 5 (5H) 0 9 (9H) >1 % 14 (EH) 3.22 %
288000 4 (4H) 0 7 (7H) 2.25 % 11 (BH) 1.38 %
384000 3 (3H) 0 5 (5H) 6.90 % 8 (8H) 1.69 %
576000 2 (2H) 0 4 (4H) 11.7 % 5 (5H) 7.83 %
1152000 1 (1H) 0 2 (2H) 11.7 % 3 (3H) 10.6 %
Remark If UCSEL bit in the S_GMR Register is set, The external UART clock “URCLK” is used as UART sourceclock.If UCSEL bit is reset, 1/2 of CPU clock is used as UART source clock.