Rainbow Electronics AT89C5131 - Manual (Page 112)

112
AT89C5131
4136A–USB–03/03
Reset Value = 00X0 XXXXb
Not Bit addressable
Serial Peripheral Data Register
(SPDAT) The Serial Peripheral Data Register (Table 80) is a read/write buffer for the receive data
register. A write to SPDAT places data directly into the shift register. No transmit buffer is
available in this model.
A Read of the SPDAT returns the value located in the receive buffer and not the content
of the shift register.
Table 80. SPDAT Register
SPDAT - Serial Peripheral Data Register (0C5H)
Reset Value = Indeterminate
R7:R0: Receive data bits
SPCON, SPSTA and SPDAT registers may be read and written at any time while there
is no on-going exchange. However, special care should be taken when writing to them
while a transmission is on-going:
• Do not change SPR2, SPR1 and SPR0
• Do not change CPHA and CPOL
• Do not change MSTR
• Clearing SPEN would immediately disable the peripheral
• Writing to the SPDAT will cause an overflow
2 -
Reserved
The value read from this bit is indeterminate. Do not set this bit
1 -
Reserved
The value read from this bit is indeterminate. Do not set this bit.
0 -
Reserved
The value read from this bit is indeterminate. Do not set this bit.
Bit
Number
Bit
Mnemonic Description
7 6 5 4 3 2 1 0
R7 R6 R5 R4 R3 R2 R1 R0