Maxim Integrated MAXQ Family Users Guide: MAXQ2000 Supplement - Manual (Page 51)

ADDENDUM TO SECTION 10: SERIAL I/O (UART) MODULE
The MAXQ2000 provides up to two serial UART modules (Serial 0 and 1 in the 68-pin package, Serial 0 in the 56-pin package), which
operate as described in the MAXQ Family User’s Guide. Table 15 shows the associated pins and Table 16 shows the associated reg-
isters for these UARTs.
Serial UART Example: Asynchronous 10-Bit Output at 115,200 Baud
move SCON0.6, #1 ; Set to mode 1 (10-bit asynchronous)
move SCON0.4, #1 ; Enable receiver
move SMD0.1, #1 ; Baud rate = 16 x baud clock
move PR0, #45E8h ; PR0 = 2^21 * 115200 / 13.5MHz (crystal)
move SCON0.0, #0 ; Clear received character flag
move SCON0.1, #0 ; Clear transmit character flag
Loop1:
move Acc, #'0' ; Start with '0' character
move LC[0], #10 ; Transmit from '0'-'9'
Loop2:
move SBUF0, Acc ; Send character
Transmit:
move C, SCON0.1 ; Check transmit flag
jump NC, Transmit ; Wait for transmit to complete
move SCON0.1, #0 ; Clear transmit flag
add #1 ; Increment character by 1
djnz LC[0], Loop2
jump Loop1
MAXQ Family User’s Guide:
MAXQ2000 Supplement
PIN NUMBER
SERIAL UART FUNCTION
68-PIN 56-PIN
MULTIPLEXED WITH PORT PIN
Serial Port 0 Receive—RXD0 53 44 P7.1
Serial Port 0 Transmit—TXD0 52 43 P7.0
Serial Port 1 Receive—RXD1 36 — P5.2
Serial Port 1 Transmit—TXD1 37 — P5.3
Table 15. Serial UART Input and Output Pins
REGISTER ADDRESS FUNCTION
SCON0 M2[06h] Serial Port 0 Control Register. Serial port mode, receive enable, 9th bit control, and interrupt flags.
SBUF0 M2[07h] Serial Port 0 Data Buffer. Input and output data buffer.
SMD0 M2[08h] Serial Port 0 Mode Register. Controls baud rate, interrupt enable, and framing error detection.
PR0 M2[09h] Serial Port 0 Phase Register. Contains counter reload value for baud rate generation.
SCON1 M3[06h] Serial Port 1 Control Register. Serial port mode, receive enable, 9th bit control, and interrupt flags.
SBUF1 M3[07h] Serial Port 1 Data Buffer. Input and output data buffer.
SMD1 M3[08h] Serial Port 1 Mode Register. Controls baud rate, interrupt enable, and framing error detection.
PR1 M3[09h] Serial Port 1 Phase Register. Contains counter reload value for baud rate generation.
Table 16. Serial UART Control Registers
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