CLK24
Baud Rate =
32 x (65536 - RCAP2H,RCAP2L)
where RCAP2H,RCAP2L is the content of RCAP2H and RCAP2L taken as a 16-bit unsigned
number.
The 32 in the denominator is the result of CLK24 being divided by 2 and the Timer 2 overflow
being divided by 16. Setting TCLK or RCLK to 1 automatically causes CLK24 to be divided
by 2, as shown in Figure C-6., instead of the 4 or 12 determined by the T2M bit in the
CKCON SFR.
To derive the required RCAP2H and RCAP2L values from a known baud rate, use the
equation:
CLK24
RCAP2H,RCAP2L =
65536 -
32 x Baud Rate
When either RCLK or TCLK is set, the TF2 flag will not be set on a Timer 2 roll over, and the
T2EX reload trigger is disabled.
Table C-11. Timer 2 Reload Values for Common Serial port Mode 1 Baud Rates
Nominal
Rate
Diviso
r
Actual
Rate
C/T2
Reload Val
Error
57600
38400
28800
19200
9600
0
0
0
0
0
0
0
13
20
F3
EC
E6
57692.31
37500
0.16%
-2.34%
0.16%
0.16%
0.16%
0.16%
0.16%
26
28846.15
19230.77
9615.385
4807.692
2403.846
39
D9
78
B2
4800
156
312
64
2400
FEC8
Note: using rates that are off by 2.3% or more will not work in all systems.
EZ-USB TRM v1.9
Appendix C: 8051 Hardware Description
C - 21
CYPRESS [ CYPRESS ]
