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11-138 SA-1100
Developer’s Manual
Peripheral Control Module
The following table shows the bit locations corresponding to the data field, parity, framing, and
receiver overrun error bits within the UART data register. Note that both FIFOs are cleared when
the SA-1100 is reset, the transmit FIFO is cleared when writing TXE=0, and the receive FIFO is
cleared when writing RXE=0.
Address: 0h 8005 0014 UTDR Read/Write
Bit 109876543210
ROR FRE PRE Bottom of receive FIFO data
Reset00000000000
Read Access
(Note: ROR, FRE, PRE are not read, but rather are transferred to
corresponding status bits in UTSR1 each time a data value is transferred to UTDR.)
Bit 76543210
Top of transmit FIFO data
Reset 00000000
Write Access
Bit Name Description
7..0 DATA
Top/bottom of transmit/receive FIFO data.
Read – Bottom of receive FIFO data.
Write – Top of transmit FIFO data.
8PRE
Parity error.
0 – No parity errors encountered in the receipt of this data (or parity disabled).
1 – Parity error encountered in the receipt of this data.
Note: Each time an 11-bit value reaches the bottom of the receive FIFO, bit 8 from the
last FIFO entry is transferred to the PRE bit in UTSR1.
9FRE
Framing error.
0 – Stop bit for this frame was a one.
1 – Stop bit for this frame was a zero.
Note: Each time an 11-bit value reaches the bottom of the receive FIFO, bit 9 from the
last FIFO entry is transferred to the FRE bit in UTSR1.
10 ROR
Receiver overrun.
0 – No receiver overrun has been detected.
1 – Receive logic attempted to place data into receive FIFO while it was full; one or more
data values following this entry were lost.
Note: Each time an 11-bit value reaches the bottom of the receive FIFO, bit 10 from the
last FIFO entry is transferred to the ROR bit in UTSR1.