Programmable FIFO threshold
Receive FIFO level
Zero byte
Time
Interrupt request
Time
Interrupt request active low
Programmable flow control threshold
LH acknowledged interrupt request
and transferred enough bytes to
recover FIFO level below
threshold
uart-024
Number
of
spaces
Programmable FIFO threshold
Transmit FIFO level
Zero byte
Time
Interrupt request
Time
Interrupt request
active low
Full level
uart-025
Preliminary
www.ti.com
Architecture
19.2.6.1 FIFO Interrupt Mode
In the FIFO interrupt mode (FIFO_EN bit in the FIFO control register (FCR[0]) is set to 1 and relevant
interrupts are enabled via the interrupt enable register (IER)), an interrupt signal informs the processor
of the status of the receiver and transmitter. These interrupts are raised when the receive/transmit FIFO
threshold (TLR[7:4] and TLR[3:0] fields or the FCR[7:6] and FCR[5:4] fields, respectively) are reached;
the interrupt signals instruct the Local Host to transfer data to the destination (from the UART module in
receive mode and/or from any source to the UART FIFO in transmit mode). Note also that in the case
of the UART flow control being enabled along with the interrupt capabilities, the user must ensure that
the UART flow control FIFO threshold (TCR[3:0]) is greater than or equal to the receive FIFO threshold.
shows the generation of the receive FIFO interrupt request.
Figure 19-19. Receive FIFO Interrupt Request Generation
In receive mode, no interrupt is generated until the receive FIFO reaches its threshold. Once low, the
interrupt can be deasserted only when the Local Host has handled enough bytes to make the FIFO
level below threshold. The flow control threshold is set at a higher value than the FIFO threshold.
shows the generation of the transmit FIFO interrupt request.
Figure 19-20. Transmit FIFO Interrupt Request Generation
In transmit mode, an interrupt request is automatically asserted when the TX FIFO is empty. This
request is deasserted when the TX FIFO crosses the threshold level. The interrupt line is deasserted
until a sufficient number of elements is transmitted to go below the TX FIFO threshold.
1701
SPRUGX9 – 15 April 2011
UART/IrDA/CIR Module
© 2011, Texas Instruments Incorporated
Содержание TMS320C6A816 Series
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