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TS-2200 User's Manual
Int 15h / Function B010h - LED Control
This function is used to turn the board LED on and off. You can also invert the LED, i.e. if the LED is
off, it will be turned on, and if it is on it will be turned off.
ENTRY:
AX = B010h
BH =
00
01
81
EXIT:
CY = 0 (carry flag)
AH = 0
Int 15h / Function B042h – Alphanumeric LCD Support
This routine enables and disables the console on the LCD interface. It supports all LCD displays sized
2 x 40 or smaller using a Hitachi HD44780 controller.
ENTRY:
AX = B042h
BH = 00
01
02
EXIT:
CY = Set if error, else clear if success. (carry flag)
AH = 00
BH = 00
01
Appendix F - Using A 12.5 MHz Baud Clock
Each serial port baud rate generator clock can be independently switched between either the
standard 1.85 MHz clock or a 12.5 MHz clock (the internal processor clock divided by 2).
Changing the clock to 12.5 MHz allows baud rates higher than 115 kbaud (up to 781 kbaud), as well
as low error, non-standard lower baud rates (such as 24 kbaud).
The baud rate clock is controlled by I/O location 0F836h:
Bit 0 controls COM1.
Bit 1 controls COM2.
Setting a bit to 0 uses the standard 1.85 MHz clock, and setting a bit to 1 uses the 12.5 MHz
processor clock. 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 example in assembly illustrates this:
MOV
DX, 0F836
IN
AL, DX
OR
AL, 00000001b
OUT
DX, AL
Note: If using automatic RS-485, see section 5.4 above.
- LED off.
- LED on.
- LED invert.
- Disable LCD
- Enable LCD
- Return current LCD status
- No Error / LCD initialized OK
- LCD currently disabled / Not present
- LCD currently enabled and running.
; load the I/O address
; read the configuration register
; switch COM1 to the 12.5 MHz clock
; write the register
19
Technologic Systems
11/06/2000
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