■ Normal Interrupts:
– Transmit Interrupt (
TI
, bit 0): Indicates that frame transmission is complete.
– Transmit Buffer Unavailable (
TU
, bit 2): Indicates the CPU owns the next descriptor in the
transmit list and the DMA cannot acquire it.
– Receive Interrupt (
RI
, bit 6): Indicates the frame reception is complete.
– Early Receive Interrupt (
ERI
, bit 14): Indicates the DMA has filled the first half of the data
buffer of the packet
■ Abnormal Interrupts:
– Transmit Process Stopped (
TPS
, bit 1): Indicates transmission is stopped.,
– Transmit Jabber Timeout (
TJT
, bit 3): Indicates the Transmit Jabber Timer expired.
– Receive FIFO Overflow (
OVF
, bit 4): Indicates the receive buffer had an overflow during frame
reception.
– Transmit Underflow (
UNF
, bit 5): Indicates the transmit buffer had an underflow during frame
transmission.
– Receive Buffer Unavailable (
RU
, bit): Indicates the CPU owns the next descriptor in the receive
list and the DMA cannot acquire it.
– Receive Process Stopped (
RPS
, bit 8): Indicates the receive process entered the STOP state.
– Receive Watchdog Timeout (
RWT
, bit 9): Indicates a frame length greater than 2 KB is received
(10,240 when Jumbo Frame is enabled)
– Early Transmit Interrupt (
ETI
, bit 10): Indicates a frame to be transmitted is fully transferred
to the TX FIFO.
– Fatal Bus Error (
FBI
, bit 13): Indicates a bus error occurred.
Any of the interrupts in the Normal Interrupt group that are enabled in the
EMACDMAIM
register
are ORed together to create the Normal Interrupt Summary (
NIS
) bit in the
EMACDMARIS
register.
Any of the interrupts in the Abnormal Interrupt group that are enabled in the
EMACDMAIM
register
are ORed together to create the Abnormal Interrupt Summary (
AIS
) bit in the
EMACDMARIS
register. Interrupts are cleared by writing a 1 to the corresponding bit position in the
EMACDMARIS
register. When all enabled interrupts within a group are cleared, the corresponding summary bit is
cleared.
Interrupts are not queued and if the interrupt event occurs again before the driver has responded
to it, no additional interrupts are generated. An interrupt is only generated once for simultaneous,
multiple events. The driver must read the
EMACDMARIS
register for the cause of the interrupt.
The
Ethernet MAC Receive Interrupt Watchdog Timer (EMACRXINTWDT)
register, offset 0xC24
can be used to control the Receive Interrupt (
RI
) assertion. If the RDES1[31] bit (Receive Interrupt)
bit has not been set in the receive descriptor and the
EMACRXINTWDT
register is programmed
with a non-zero value, it gets activated as soon as the RX DMA completes a transfer of a received
frame to system memory without asserting the receive interrupt. When this counter runs out as per
the programmed value, the
RI
bit is set in the
EMACDMARIS
register and the interrupt is asserted
1433
June 18, 2014
Texas Instruments-Production Data
Tiva
™
TM4C1294NCPDT Microcontroller