Espressif ESP32 Technical Reference Manual page 265

10 Ethernet Media Access Controller (MAC)
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EMACINTERFRAMEGAP These bits control the minimum IFG between frames during transmission.
(R/W)
• 3'b000: 96 bit times.
• 3'b001: 88 bit times.
• 3'b010: 80 bit times.
• 3'b111: 40 bit times. In the half-duplex mode, the minimum IFG can be configured only for
64 bit times (IFG = 100). Lower values are not considered.
EMACDISABLECRS When set high, this bit makes the MAC transmitter ignore the MII CRS signal
during frame transmission in the half-duplex mode. This request results in no errors generated
because of Loss of Carrier or No Carrier during such transmission. When this bit is low, the MAC
transmitter generates such errors because of Carrier Sense and can even abort the transmis-
sions. (R/W)
EMACMII This bit selects the Ethernet line speed. It should be set to 1 for 10 or 100 Mbps operations.
In 10 or 100 Mbps operations, this bit, along with FES(EMACFESPEED) bit, it selects the exact
linespeed. In the 10/100 Mbps-only operations, the bit is always 1. (R/W)
EMACFESPEED This bit selects the speed in the MII, RMII interface. 0: 10 Mbps; 1: 100 Mbps.
(R/W)
EMACRXOWN When this bit is set, the MAC disables the reception of frames when the TX_EN is
asserted in the half-duplex mode. When this bit is reset, the MAC receives all packets that are
given by the PHY while transmitting. This bit is not applicable if the MAC is operating in the
full-duplex mode. (R/W)
EMACLOOPBACK When this bit is set, the MAC operates in the loopback mode MII. The MII Receive
clock input (CLK_RX) is required for the loopback to work properly, because the transmit clock
is not looped-back internally. (R/W)
EMACDUPLEX When this bit is set, the MAC operates in the full-duplex mode where it can transmit
and receive simultaneously. This bit is read only with default value of 1'b1 in the full-duplex-mode.
(R/W)
EMACRXIPCOFFLOAD When this bit is set, the MAC calculates the 16-bit one's complement of the
one's complement sum of all received Ethernet frame payloads. It also checks whether the IPv4
Header checksum (assumed to be bytes 25/26 or 29/30 (VLAN-tagged) of the received Ethernet
frame) is correct for the received frame and gives the status in the receive status word. The MAC
also appends the 16-bit checksum calculated for the IP header datagram payload (bytes after
the IPv4 header) and appends it to the Ethernet frame transferred to the application (when Type
2 COE is deselected). When this bit is reset, this function is disabled. (R/W)
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Espressif Systems
Register 10.15. EMACCONFIG_REG (0x1000)
265
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ESP32 TRM (Version 5.2)