
ADSP-BF59x Blackfin Processor Hardware Reference
11-25
UART Port Controllers
cleared when the
UART_LSR
register is read. Invalid parity bits can be simu-
lated by setting the
FPE
bit in the
UART_GCTL
register.
The
FE
bit indicates that the first stop bit has been sampled low. It is
cleared by hardware when the
UART_RBR
register is read. Invalid stop bits
can be simulated by setting the
FFE
bit in the
UART_GCTL
register.
The
BI
bit indicates that the first stop bit has been sampled low and the
entire data word, including parity bit, consists of low bits only. It is
cleared by hardware when the
UART_RBR
register is read.
Because of the destructive nature of these read operations, special
care should be taken. For more information, see the
Memory
chap-
ter of the
ADSP-BF59x Blackfin Processor Hardware Reference
.
The
THRE
bit indicates that the UART transmit channel is ready for new
data and software can write to
UART_THR
. Writes to
UART_THR
clear the
THRE
bit. It is set again when data is passed from
UART_THR
to the internal
TSR
register.
The
TEMT
bit indicates that both the
UART_THR
register and the internal
TSR
register are empty. In this case the program is permitted to write to the
UART_THR
register twice without losing data. The
TEMT
bit can also be used
as an indicator that pending UART transmission has been completed. At
that time it is safe to disable the
UCEN
bit or to three-state the off-chip line
driver.
UART Transmit Holding (UART_THR) Register
The write-only
UART_THR
register, shown in
Figure 11-10
, is mapped to
the same address as the read-only
UART_RBR
and
UART_DLL
registers. To
access
UART_THR
, the
DLAB
bit in
UART_LCR
must be cleared. When the
DLAB
bit is cleared, writes to this address target the
UART_THR
register, and reads
from this address return the
UART_RBR
register.
Summary of Contents for ADSP-BF59x Blackfin
Page 64: ...Development Tools 1 22 ADSP BF59x Blackfin Processor Hardware Reference...
Page 74: ...Processor Specific MMRs 2 10 ADSP BF59x Blackfin Processor Hardware Reference...
Page 244: ...Programming Examples 6 40 ADSP BF59x Blackfin Processor Hardware Reference...
Page 700: ...Programming Examples 16 78 ADSP BF59x Blackfin Processor Hardware Reference...
Page 738: ...Boundary Scan Architecture B 8 ADSP BF59x Blackfin Processor Hardware Reference...