Appendix F - Using A Higher Rate (10X) Baud Clock - Technologic Systems TS-5400 User Manual

TS-5400 User's Manual

Appendix F - Using a Higher Rate (10x) Baud Clock

The COM1 and COM2 serial port baud rate generator clock can be independently switched between
either the standard 1.8432 MHz clock or a ten times rate of 18.432 MHz clock.
Changing to the 10x rate allows baud rates higher than 115.2 kbaud (such as 230.4 kbaud or 1152
kbaud), as well as, non-standard lower baud rates (such as 24 kbaud).
The baud rate clock for each COM port is controlled by bit 2 in the UART Control Register (UART1CTL
and UART2CTL):
UART1CTL @ DFCC0h
UART2CTL @ DFCC4h
Clearing bit 2 to a "0" will change the clock to the 10X rate.
NOTE: You must not modify the other bits of this register. You must use a read-modify-write
procedure to change these bits.
The following code written in Turbo C provides an example for changing COM1 to run at a 10X Baud
rate:
int main () {
unsigned char far *comreg;
unsigned char comvalue;
comreg=(unsigned char far *) MK_FP (0xDF00, 0xCC0);
comvalue = *comreg;
comvalue = comvalue & 0xFB
*comreg = comvalue;
return 0;
}
/* Load Register */
/*Modify it*/
/*Write it out*/
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Technologic Systems
10/31/03