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ADSP-BF537 Blackfin Processor Hardware Reference
13-29
UART Port Controllers
UARTx_IIR Registers
When cleared, the
NINT
bit signals that an interrupt is pending. The
STA-
TUS
field indicates the highest priority pending interrupt. The receive line
status has the highest priority; the
UARTx_THR
empty interrupt has the low-
est priority. In the case where both interrupts are signalling, the
UARTx_IIR
reads 0x06.
When a UART interrupt is pending, the interrupt service routine (ISR)
needs to clear the interrupt latch explicitly.
clear any of the three latches.
The TX interrupt request is cleared by writing new data to the
UARTx_THR
register or by reading the
UARTx_IIR
register. Please note the special role of
the
UARTx_IIR
register read in the case where the service routine does not
want to transmit further data.
If software stops transmission, it must read the
UARTx_IIR
register to reset
the interrupt request. As long as the
UARTx_IIR
register reads 0x04 or 0x06
(indicating that another interrupt of higher priority is pending), the
UARTx_THR
empty latch cannot be cleared by reading
UARTx_IIR
.
Figure 13-13. UART Interrupt Identification Registers
NINT (Pending interrupt)
UART Interrupt Identification Registers (UARTx_IIR)
RO
STATUS[1:0]
0 - Interrupt pending
1 - No interrupt pending
00 - Reserved
01 - UARTx_THR empty. Write UARTx_THR or read UARTx_IIR to clear
interrupt request.
10 - Receive data ready. Read UART RBR to clear interrupt request.
11 - Receive line status. Read UARTx_LSR to clear interrupt request.
15 14
13 12
11 10
9
8
7
6
5
4
3
2
1
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Reset = 0x0001
UART0:
0xFFC0 0408
UART1:
0xFFC0 2008
Содержание Blackfin ADSP-BF537
Страница 42: ...Contents xlii ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 90: ...Development Tools 1 32 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 138: ...Programming Examples 4 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 340: ...SDC Programming Examples 6 84 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 606: ...Programming Examples 9 94 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 660: ...Programming Examples 10 54 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 720: ...Electrical Specifications 11 60 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 840: ...Programming Examples 13 42 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 876: ...Programming Examples 14 36 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 938: ...Programming Examples 15 62 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 958: ...Programming Examples 17 12 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 986: ...Programming Examples 18 28 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 1162: ...G 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 1218: ...Index I 56 ADSP BF537 Blackfin Processor Hardware Reference ...