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RM0090: Reference manual - STMicroelectronics

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Ethernet (ETH): media access control (MAC) with DMA controller <strong>RM0090</strong><br />

Ethernet DMA missed frame and buffer overflow counter register<br />

(ETH_DMAMFBOCR)<br />

Address offset: 0x1020<br />

Reset value: 0x0000 0000<br />

The DMA maintains two counters to track the number of missed frames during reception.<br />

This register reports the current value of the counter. The counter is used for diagnostic<br />

purposes. Bits [15:0] indicate missed frames due to the STM32F4xx buffer being<br />

unavailable (no receive descriptor was available). Bits [27:17] indicate missed frames due to<br />

Rx FIFO overflow conditions and runt frames (good frames of less than 64 bytes).<br />

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<br />

Reserved OFOC<br />

rc_<br />

r<br />

rc_<br />

r<br />

rc_<br />

r<br />

rc_<br />

r<br />

rc_<br />

r<br />

rc_<br />

r<br />

MFA<br />

rc_<br />

r<br />

Bits 31:29 Reserved, must be kept at reset value.<br />

Ethernet DMA receive status watchdog timer register (ETH_DMARSWTR)<br />

Address offset: 0x1024<br />

Reset value: 0x0000 0000<br />

This register, when written with a non-zero value, enables the watchdog timer for the receive<br />

status (RS, ETH_DMASR[6]).<br />

1011/1416 Doc ID 018909 Rev 3<br />

rc_<br />

r<br />

rc_<br />

r<br />

Bit 28 OFOC: Overflow bit for FIFO overflow counter<br />

rc_<br />

r<br />

Bits 27:17 MFA: Missed frames by the application<br />

Indicates the number of frames missed by the application<br />

Bit 16 OMFC: Overflow bit for missed frame counter<br />

rc_<br />

r<br />

rc_<br />

r<br />

OMFC<br />

rc_<br />

r<br />

rc_<br />

r<br />

rc_<br />

r<br />

Bits 15:0 MFC: Missed frames by the controller<br />

Indicates the number of frames missed by the Controller due to the host receive buffer being<br />

unavailable. This counter is incremented each time the DMA discards an incoming frame.<br />

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<br />

Reserved<br />

Bits 31:8 Reserved, must be kept at reset value.<br />

rc_<br />

r<br />

rc_<br />

r<br />

rc_<br />

r<br />

rc_<br />

r<br />

rc_<br />

r<br />

MFC<br />

rc_<br />

r<br />

rc_<br />

r<br />

rc_<br />

r<br />

rc_<br />

r<br />

rc_<br />

r<br />

rc_<br />

r<br />

RSWTC<br />

rc_<br />

r<br />

rc_<br />

r<br />

rc_<br />

r<br />

rw rw rw rw rw rw rw rw<br />

Bits 7:0 RSWTC: Receive status (RS) watchdog timer count<br />

Indicates the number of HCLK clock cycles multiplied by 256 for which the watchdog timer<br />

is set. The watchdog timer gets triggered with the programmed value after the RxDMA<br />

completes the transfer of a frame for which the RS status bit is not set due to the setting of<br />

RDES1[31] in the corresponding descriptor. When the watchdog timer runs out, the RS bit<br />

is set and the timer is stopped. The watchdog timer is reset when the RS bit is set high due<br />

to automatic setting of RS as per RDES1[31] of any received frame.

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