STM32F101xx, STM32F102xx, STM32F103xx, STM32F105xx and ...

Ethernet (ETH): media access control (MAC) with DMA controller
RM0008
Note:
When an Ethernet wakeup event mapped on EXTI Line19 occurs and the MAC PMT
interrupt is enabled and the EXTI Line19 interrupt, with detection on rising edge, is also
enabled, both interrupts are generated.
A watchdog timer (see ETH_DMARSWTR register) is given for flexible control of the RS bit
(ETH_DMASR register). When this watchdog timer is programmed with a non-zero value, it
gets activated as soon as the RxDMA completes a transfer of a received frame to system
memory without asserting the Receive Status because it is not enabled in the corresponding
Receive descriptor (RDES1[31]). When this timer runs out as per the programmed value,
the RS bit is set and the interrupt is asserted if the corresponding RIE is enabled in the
ETH_DMAIER register. This timer is disabled before it runs out, when a frame is transferred
to memory and the RS is set because it is enabled for that descriptor.
Reading the PMT control and status register automatically clears the Wakeup Frame
Received and Magic Packet Received PMT interrupt flags. However, since the registers for
these flags are in the CLK_RX domain, there may be a significant delay before this update is
visible by the firmware. The delay is especially long when the RX clock is slow (in 10 Mbit
mode) and when the AHB bus is high-frequency.
Since interrupt requests from the PMT to the CPU are based on the same registers in the
CLK_RX domain, the CPU may spuriously call the interrupt routine a second time even after
reading PMT_CSR. Thus, it may be necessary that the firmware polls the Wakeup Frame
Received and Magic Packet Received bits and exits the interrupt service routine only when
they are found to be at ‘0’.
27.8 Ethernet register descriptions
27.8.1 MAC register description
Ethernet MAC configuration register (ETH_MACCR)
Address offset: 0x0000
Reset value: 0x0000 8000
The MAC configuration register is the operation mode register of the MAC. It establishes
receive and transmit operating modes.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Reserved
WD
JD
Reserved
IFG
CSD
Reserved
FES
ROD
LM
DM
IPCO
RD
Reserved
APCS
BL
DC
TE
RE
rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw
Reserved
Bits 31:24 Reserved
Bit 23 WD: Watchdog disable
When this bit is set, the MAC disables the watchdog timer on the receiver, and can receive
frames of up to 16 384 bytes.
When this bit is reset, the MAC allows no more than 2 048 bytes of the frame being received
and cuts off any bytes received after that.
906/995 Doc ID 13902 Rev 9