ADSP-BF537 Blackfin Processor Hardware Reference
13-11
UART Port Controllers
transmit and receive requests cannot be forwarded. Refer to the descrip-
tion of the peripheral map registers
chapter.
Transmit interrupts are enabled by the
ETBEI
bit in the
UARTx_IER
register.
If set, the transmit request is asserted when the
THRE
bit in the
UART_LSR
register transitions from 0 to 1, indicating that the TX buffer is ready for
new data.
Note that the
THRE
bit resets to 1. When the
ETBEI
bit is set in the
UARTx_IER
register, the UART module immediately issues an interrupt or
DMA request. This way, no special handling of the first character is
required when transmission of a string is initiated. Simply set the
ETBEI
bit and let the interrupt service routine load the first character from mem-
ory and write it to the
UARTx_THR
register in the normal manner.
Accordingly, the
ETBEI
bit can be cleared if the string transmission has
completed. For more information, see
.
The
THRE
bit is cleared by hardware when new data is written to the
UARTx_THR
register. These writes also clear the TX interrupt request. How-
ever, they also initiate further transmission. If software doesn’t want to
continue transmission, the TX request can alternatively be cleared by
either clearing the
ETBEI
bit or by reading the
UARTx_IIR
register.
Receive interrupts are enabled by the
ERBFI
bit in the
UARTx_IER
register.
If set, the receive request is asserted when the
DR
bit in the
UART_LSR
regis-
ter transitions from 0 to 1, indicating that new data is available in the
UARTx_RBR
register. When software reads the
UARTx_RBR
, hardware clears
the
DR
bit again. Reading
UARTx_RBR
also clears the RX interrupt request.
Status interrupts are enabled by the
ERBFI
bit in the
UARTx_IER
register. If
set, the status interrupt request is asserted when any error bit in the
UART_LSR
register transitions from 0 to 1. Refer to
for details. Reading the
UARTx_LSR
register clears the
error bits destructively. These reads also clear the status interrupt request.
Summary of Contents for Blackfin ADSP-BF537
Page 42: ...Contents xlii ADSP BF537 Blackfin Processor Hardware Reference ...
Page 90: ...Development Tools 1 32 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 138: ...Programming Examples 4 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 340: ...SDC Programming Examples 6 84 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 606: ...Programming Examples 9 94 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 660: ...Programming Examples 10 54 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 720: ...Electrical Specifications 11 60 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 840: ...Programming Examples 13 42 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 876: ...Programming Examples 14 36 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 938: ...Programming Examples 15 62 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 958: ...Programming Examples 17 12 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 986: ...Programming Examples 18 28 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1162: ...G 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1218: ...Index I 56 ADSP BF537 Blackfin Processor Hardware Reference ...