RMII Protocolos suportados

Computadores e servidores

Reduced Media Independent Interface

O que é RMII?

RMII (Reduced Media Independent Interface) is a simplified version of MII that reduces the pin count for 10/100 Mbps Ethernet MAC-to-PHY connections. RMII uses 2-bit-wide transmit and receive data paths (instead of 4-bit), sharing a single 50 MHz reference clock (instead of separate TX and RX clocks). This reduced pin count makes RMII popular in space-constrained designs and microcontrollers with limited pin availability. The trade-off is a higher clock frequency and tighter timing requirements. Engineers debugging embedded Ethernet implementations frequently encounter RMII interface issues related to clock distribution, timing alignment, and reference clock quality.

RMII Referência rápida

type Parallel, reduced pin count
signals TXD[1:0], RXD[1:0], REF_CLK, etc.
max Speed 50 MHz (100 Mbps)
voltage Range 3.3V
standard IEEE 802.3u

Instrumentos Acute compatíveis com RMII

Soluções recomendadas

Recomendado para decodificação

TL4234B

TL4234B

Todos os produtos compatíveis

Decodificação de protocolo
Disparo por hardware
Emulador de protocolo

Série LA4000

Série MSO2000

Série MSO3000

Série TravelLogic

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Como analisar RMII com instrumentos Acute

1

Conecte seu analisador lógico Acute aos sinais RMII: TXD[1:0], RXD[1:0], REF_CLK, TX_EN e CRS_DV.

2

Conecte um fio terra a referência de terra da placa alvo.

3

No software Acute, selecione o RMII protocol decoder e atribua cada sinal ao canal de entrada correspondente.

4

Configure os parametros esperados de Ethernet speed (10 or 100 Mbps).

5

Capture e visualize os Ethernet frames for both transmit and receive directions, verifying frame integrity and timing.

Perguntas frequentes

Qual taxa de amostragem e necessária para a análise RMII ?
RMII uses a 50 MHz reference clock. Sample at a minimum of 200 MHz (4x the clock) for reliable decoding. A sample rate of 500 MHz or higher is recommended for accurate timing analysis of data setup and hold times, which are critical for diagnosing intermittent RMII link issues.
Por que meu link Ethernet RMII cai intermitentemente?
Intermittent RMII link issues are frequently caused by reference clock quality problems — jitter, duty cycle distortion, or routing-induced skew between the clock and data signals. Capture the REF_CLK alongside the data signals and measure timing margins. Also verify that the CRS_DV signal is properly de-multiplexing carrier sense and receive data valid, as incorrect CRS_DV interpretation can cause frame reception failures.
Quantos canais são necessários para a análise de RMII ?
Full bidirectional RMII analysis requires 7 channels: TXD[1:0], TX_EN, RXD[1:0], CRS_DV, and REF_CLK. For monitoring only one direction (transmit or receive), 4 channels are sufficient. If you also need to monitor MDIO management bus traffic alongside RMII, add 2 more channels for MDC and MDIO.

Protocolos relacionados

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