at89c5131 ATMEL Corporation, at89c5131 Datasheet - Page 98

• Manufacturer Part Number: at89c5131
• Description: 8-bit Flash Microcontroller With Full Speed Usb Device At89c5131
• Manufacturer: ATMEL Corporation

Serial Peripheral Data Register
(SPDAT)
4136C–USB–04/05
Reset Value = 00X0 XXXXb
Not Bit addressable
The Serial Peripheral Data Register (Table 77) 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 77. 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:
•
•
•
•
•
Number
Bit
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
R7
7
2
1
0
Mnemonic Description
Bit
R6
6
-
-
-
Reserved
The value read from this bit is indeterminate. Do not set this bit
Reserved
The value read from this bit is indeterminate. Do not set this bit.
Reserved
The value read from this bit is indeterminate. Do not set this bit.
R5
5
R4
4
R3
3
R2
2
AT89C5131
R1
1
R0
0
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