Freescale Semiconductor POWERPC MPC860T - Manual (Page 40)

6-8 MPC860T (Rev. D) Fast Ethernet Controller Supplement MOTOROLA
PRELIMINARYÑSUBJECT TO CHANGE WITHOUT NOTICE
Table 6-9 describes ECNTRL Þelds.
6.2.9 Interrupt Event (I_EVENT)/Interrupt Mask Register (I_MASK)
When an event sets a bit in the interrupt event register (I_EVENT), shown in Figure 6-9, an
interrupt is generated if the corresponding interrupt mask register (I_MASK) bit is set.
I_EVENT bits are cleared by writing ones; writing zeros has no effect.
Table 6-10 describes I_EVENT and I_MASK Þelds. Note that neither the RxBD or TxBD
has an I bit to enable/disable an interrupt on the receive or transmit buffer. As events occur,
they are always reported in I_EVENT, but only those not masked in I_MASK cause an
interrupt. From a system resources and software performance standpoint, it is advisable to
minimize the number of interrupts per frame by masking TXB and RXB in favor of TFINT
Table 6-9. ECNTRL Field Descriptions
Bits Name Description
0Р7 С Reserved. These Þelds may return unpredictable values and should be masked on a read.
Users should always write these Þelds to zero.
8Р28 С These Þelds may return unpredictable values and should be masked on a read. Users should
always write these Þelds to zero.
29 FEC_PINMUX FEC enable. Read/write. The user must set this bit to enable the FEC function in the 860 in
conjunction with 860 pin multiplexing control.
30 ETHER_EN Ethernet enable.
0 A transfer is stopped after a bad CRC is appended to any frame being sent.
1 The FEC is enabled, and reception and transmission are possible.
The BDs for an aborted transmit frame are not updated after ETHER_EN is cleared. When
ETHER_EN is cleared, the DMA, BD, and FIFO control logic are reset including BD and FIFO
pointers. See Section 6.3.2, ÒUser Initialization (before Setting ECNTRL[ETHER_EN]).Ó
31 RESET Ethernet controller reset. When RESET = 1, the equivalent of a hardware or software reset is
performed but it is local to the FEC. ETHER_EN is cleared and all other FEC registers take
their reset values. Also, any transfers are abruptly aborted. Hardware automatically clears
RESET once the hardware reset is complete (approximately 16 clock cycles).
Bits 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Field HBERR BABR BABT GRA TFINT TXB RFINT RXB MII EBERR Ñ
Reset 0000_0000_0000_0000
R/W Read/write
Addr 0xE44 (I_EVENT); 0xE48 (I_MASK)
Bits 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Field Ñ
Reset 0000_0000_0000_0000
R/W Read/write
Addr 0xE46(I_EVENT); 0xE4A (I_MASK)
Figure 6-9. I_EVENT/I_MASK Registers
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