DS80C320 Datasheet, PDF (14/38 Pages) Dallas Semiconductor – High-Speed/Low-Power Micro

DS80C320/DS80C323 High-Speed/Low-Power Microcontrollers
64-Byte Block Move with Dual Data Pointer
; SH and SL are high and low byte source address.
; DH and DL are high and low byte of destination address.
; DPS is the data pointer select. Reset condition is DPS=0, DPTR0 is selected.
# CYCLES
EQU
DPS, #86h
; TELL ASSEMBLER ABOUT DPS
MOV
R5, #64
; NUMBER OF BYTES TO MOVE
2
MOV
DPTR, #DHDL
; LOAD DESTINATION ADDRESS
3
INC
DPS
; CHANGE ACTIVE DPTR
2
MOV
DPTR, #SHSL
; LOAD SOURCE ADDRESS
2
MOVE:
; THIS LOOP IS PERFORMED THE NUMBER OF TIMES LOADED INTO R5, IN THIS EXAMPLE 64
MOVX
A, @DPTR
; READ SOURCE DATA BYTE
2
INC
DPS
; CHANGE DPTR TO DESTINATION
2
MOVX
@DPTR, A
; WRITE DATA TO DESTINATION
2
INC
DPTR
; NEXT DESTINATION ADDRESS
3
INC
DPS
; CHANGE DATA POINTER TO SOURCE
2
INC
DPTR
; NEXT SOURCE ADDRESS
3
DJNZ
R5, MOVE
; FINISHED WITH TABLE?
3
PERIPHERAL OVERVIEW
Peripherals in the DS80C320/DS80C323 are accessed using the SFRs. The devices provide several of the
most commonly needed peripheral functions in microcomputer-based systems. These functions are new
to the 80C32 family and include a second serial port, power-fail reset, power-fail interrupt, and a
programmable watchdog timer. These are briefly described in the following paragraphs. More details are
available in the High-Speed Microcontroller User’s Guide.
SERIAL PORTS
The DS80C320/DS80C323 provide a serial port (UART) that is identical to the 80C32. Many
applications require serial communication with multiple devices. Therefore, a second hardware serial port
is provided that is a full duplicate of the standard one. It optionally uses pins P1.2 (RXD1) and P1.3
(TXD1). This port has duplicate control functions included in new SFR locations. The second serial port
operates in a comparable manner with the first. Both can operate simultaneously but can be at different
baud rates.
The second serial port has similar control registers (SCON1 at C0h, SBUF1 at C1h) to the original. One
difference is that for timer-based baud rates, the original serial port can use Timer 1 or Timer 2 to
generate baud rates. This is selected via SFR bits. The new serial port can only use Timer 1.
TIMER-RATE CONTROL
One important difference exists between the DS80C320/DS80C323 and 80C32 regarding timers. The
original 80C32 used a 12 clock-per-cycle scheme for timers and consequently for some serial baud rates
(depending on the mode). The DS80C320/DS80C323 architecture normally runs using 4 clocks per cycle.
However, in the area of timers, it will default to a 12 clock-per-cycle scheme on a reset. This allows
existing code with real-time dependencies such as baud rates to operate properly. If an application needs
higher speed timers or serial baud rates, the timers can be set to run at the 4-clock rate.
The Clock Control register (CKCON - 8Eh) determines these timer speeds. When the relevant CKCON
bit is a logic 1, the device uses 4 clocks per cycle to generate timer speeds. When the control bit is set to a
0, the device uses 12 clocks for timer speeds. The reset condition is a 0. CKCON.5 selects the speed of
Timer 2. CKCON.4 selects Timer 1 and CKCON.3 selects Timer 0. Note that unless a user desires very
fast timing, it is unnecessary to alter these bits. Note that the timer controls are independent.
14 of 38