EMAC MicroPac 535, Справочник по аппаратуре

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MEMORY MAPPED I/O
Memory mapped I/O (MMIO) is implemented in the external data memory addresses 0000-7FFF when P5.1=0. For example:
CLR P5.1 ; this enables MMIO
MOV DPH,#<port addr> ; DPH selects the port (DPL has no effect)
MOVX A,@DPTR ; read the current port
MOVX @DPTR,A ; write to the current port
Note that since the I/O decoding logic uses only the A8-A15 lines, only DPH (data pointer high byte register) is significant; the value of DPL
has no effect. Therefore, if DPL changes but neither P5.1 nor DPH are changed, the same port will be selected.
I/O PORTS
The I/O ports should not be confused with the special function registers. Though they may have similar purposes, the method of access is
different as just shown. The I/O port values that should be loaded into DPH are as follows:
Physical MMIO
Value for DPH Address range Description
70H-7FH 7000H-7FFFH EXTERNAL I/O (Chip select for devices connected to expansion connector)
30H 3000H-3FFFH KEYPAD INTERFACE (read only)
20H-21H 2000H-2FFFH LCD INTERFACE (20H=LCD command, 21H=data)
10H-13H 1000H-1FFFH D/A OUTPUT (channels A,B,C and D correspond to DPH values 10H to 13H respectively)
00H-0FH 0000H-0FFFH SC26C92 (COM1, COM2, timer/counter and digital I/O ports,)
Below is a detailed list of the SC26C92's ports (wr indicates a write register and rd a read register).
Value for DPH LABEL DESCRIPTION
00H MR1A: Mode register a (MR1A, MR2A) (rd/wr)
01H SRA: Status register A (rd)
01H CSRA: Clock select register A (wr)
02H BRGTST: Baud rate generator test (rd)
02H CRA: Command register A (wr)
03H RHRA: RX holding register A (rd)
03H THRA: TX holding register A (wr)
04H IPCR: Input port change register (rd)
04H ACR: Auxiliary control register (wr)
05H ISR: Interrupt status register (rd)
05H IMR: Interrupt mask register (wr)
06H CTU: Counter timer upper (wr)
06H CTUR: Counter timer upper read (rd)
07H CTL: Counter timer lower (wr)
07H CTLR: Counter timer lower read (rd)
08H MR1B: Mode register B (rd/wr)
09H SRB: Status register B (rd)
09H CSRB: Clock select register B (wr)
0AH TST1X16: 1X/16X test (rd)
0AH CRB: Command register B (wr)
0BH RHRB: RX holding register B (rd)
0BH THRB: TX holding register B (wr)
0DH UARTIN: Input port (rd)
0DH OPCR: Output port configuration register (wr)
0EH STRTCNT: Start counter command
0EH OUTSET: Set output port bits command
0FH STOPCNT: Stop counter command
0FH OUTRES: Reset output port bits command (wr)