Philips Semiconductors Product data sheet
SC28L91
3.3 V or 5.0 V Universal Asynchronous
Receiver/Transmitter (UART)
2004 Oct 21 26
CSR CLOCK SELECT REGISTER
Addr CSR (7:4) CSR (3:0)
CSR RECEIVER CLOCK SELECT TRANSMITTER CLOCK SELECT
0x01 See Text and table 5 See Text and table 5
Table 5. Baud rate (base on a 3.6864MHz crystal clock)
MR0[0] = 0 (Normal Mode) MR0[0] = 1 (Extended Mode I) MR0[2] = 1 (Extended Mode II)
CSRA[7:4] ACR[7] = 0 ACR[7] = 1 ACR[7] = 0 ACR[7] = 1 ACR[7] = 0 ACR[7] = 1
0000 50 75 300 450 4,800 7,200
0001 110 110 110 110 880 880
0010 134.5 134.5 134.5 134.5 1,076 1,076
0011 200 150 1200 900 19.2K 14.4K
0100 300 300 1800 1800 28.8K 28.8K
0101 600 600 3600 3600 57.6K 57.6K
0110 1,200 1,200 7200 7,200 115.2K 115.2K
0111 1,050 2,000 1,050 2,000 1,050 2,000
1000 2,400 2,400 14.4K 14.4K 57.6K 57.6K
1001 4,800 4,800 28.8K 28.8K 4,800 4,800
1010 7,200 1,800 7,200 1,800 57.6K 14.4K
1011 9,600 9,600 57.6K 57.6K 9,600 9,600
1100 38.4K 19.2K 230.4K 115.2K 38.4K 19.2K
1101 Timer Timer Timer Timer Timer Timer
1110 IP4–16X IP4–16X IP4–16X IP4–16X IP4–16X IP4–16X
1111 IP4–1X IP4–1X IP4–1X IP4–1X IP4–1X IP4–1X
NOTE:
1. The receiver clock is always a 16X clock except for CSR[7:4] = 1111. CSR[3:0]— Transmitter Clock Select. This field selects the baud rate
clock for the transmitter.
The field definition is as shown in Table 5, except as follows:
CSR[3:0]
1110 IP3 –16X
1111 IP3 –1X
The transmitter clock is always a 16X clock except for CSR[3:0] = 1111.
Table 6. Bit rate generator characteristics for Crystal or Clock = 3.6864MHz
NORMAL RATE (BAUD) ACTUAL 16X CLOCK (KHz) ERROR (%)
50 0.8 0
75 1.2 0
110 1.759 –0.069
134.5 2.153 0.059
150 2.4 0
200 3.2 0
300 4.8 0
600 9.6 0
1050 16.756 –0.260
1200 19.2 0
1800 28.8 0
2000 32.056 0.175
2400 38.4 0
4800 76.8 0
7200 115.2 0
9600 153.6 0
19.2K 307.2 0
38.4K 614.4 0
NOTE:
Duty cycle of 16X clock is 50% 1%