PIC16F870/871
TABLE 9-8:
REGISTERS ASSOCIATED WITH SYNCHRONOUS MASTER TRANSMISSION
Value on:
POR,
BOR
Value on all
other Resets
Address Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
(1)
0Ch
18h
19h
8Ch
98h
99h
PIR1
PSPIF
ADIF
RCIF
TXIF
—
—
CCP1IF TMR2IF TMR1IF 0000 -000
0000 -000
0000 -00x
0000 0000
0000 -000
0000 -010
0000 0000
RCSTA
SPEN
RX9
SREN CREN
FERR
OERR
RX9D
0000 -00x
0000 0000
TXREG USART Transmit Register
(1)
PIE1
PSPIE
CSRC
ADIE
TX9
RCIE
TXIE
—
—
CCP1IE TMR2IE TMR1IE 0000 -000
TXSTA
TXEN SYNC
BRGH
TRMT
TX9D
0000 -010
0000 0000
SPBRG Baud Rate Generator Register
Legend: x= unknown, -= unimplemented, read as '0'. Shaded cells are not used for synchronous master transmission.
Note 1: Bits PSPIE and PSPIF are reserved on the PIC16F870; always maintain these bits clear.
FIGURE 9-9: SYNCHRONOUS TRANSMISSION
Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4
Q3Q4 Q1Q2 Q3Q4 Q1Q2Q3Q4 Q1Q2Q3Q4Q1Q2Q3 Q4Q1Q2Q3Q4Q1 Q2Q3 Q4
RC7/RX/DT pin
RC6/TX/CK pin
bit 0
bit 1
bit 2
bit 7
bit 0
bit 1
WORD 2
bit 7
WORD 1
Write to
TXREG reg
Write word1
Write word2
TXIF bit
(Interrupt flag)
TRMT
TRMT bit
’1’
’1’
TXEN bit
Note: Sync master mode; SPBRG = '0'. Continuous transmission of two 8-bit words
FIGURE 9-10: SYNCHRONOUS TRANSMISSION (THROUGH TXEN)
RC7/RX/DT pin
RC6/TX/CK pin
bit0
bit2
bit1
bit6
bit7
Write to
TXREG reg
TXIF bit
TRMT bit
TXEN bit
DS30569A-page 74
Preliminary
1999 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
