with the
IIR_FCR.FIFOE
bit, automatic flow control is also disabled regardless of any other settings.
When auto CTS is not implemented or disabled, the transmitter is unaffected by
cts_n
.†
Figure 21-3: Automatic CTS Timing
sout
cts_n
start
data bits
stop
start
Disabled
data bits
stop
start
data bits
stop
Clocks
The UART controller is connected to the
l4_sp_clk
clock. The clock input is driven by the clock manager.
Related Information
on page 2-1
For more information, refer to the
Clock Manager
chapter.
Resets
The UART controller is connected to the
uart_rst_n
reset signal. The reset manager drives the signal
on a cold or warm reset.
Related Information
on page 3-1
For more information, refer to the
Reset Manager
chapter.
Interrupts
The assertion of the UART interrupt output signal occurs when one of the following interrupt types are
enabled and active: †
Table 21-2: Interrupt Types and Priority †
Priority
Interrupt Type
Highest
Receiver line status
Second
Received data available
Second
Character timeout indication
Third
Transmit holding register empty
You can enable the interrupt types with the interrupt enable register (
IER_DLH
).
Programmable THRE Interrupt
The UART has a programmable THRE interrupt mode to increase system performance. You enable the
programmable THRE interrupt mode with the interrupt enable register (
IER_DLH.PTIME
). When the
THRE mode is enabled, THRE interrupts and the
dma_tx_req
signal are active at and below a programmed
transmit FIFO buffer empty threshold level, as shown in the flowchart. †
Altera Corporation
UART Controller
21-5
Clocks
cv_54021
2013.12.30