What does RMII mean?
Reduced media-independent interface (RMII) is a standard which was developed to reduce the number of signals required to connect a PHY to a MAC.
What is Ethernet RMII?
MII vs RMII for Ethernet Therefore, RMII (reduced MII) was developed as a variant of MII to cut the number of unshareable signals per PHY interface in half (down to 8 per PHY). The RMII specification is also capable of supporting 10 Mbps and 100 Mbps data rates, and there are gigabit-capable variants.
What is a Ethernet MAC?
What is an Ethernet MAC? The MAC is the media access controller. The Ethernet MAC is defined by the IEEE-802.3 Ethernet standard. It implements a data-link layer. The latest MACs support operation at both 10 Mbits/s and 100 Mbits/s.
Why is PHY used?
A PHY connects a link layer device (often called MAC as an acronym for medium access control) to a physical medium such as an optical fiber or copper cable. A PHY device typically includes both physical coding sublayer (PCS) and physical medium dependent (PMD) layer functionality.
What is difference between PHY and MAC?
This page compares PHY vs MAC layers and mention difference between PHY and MAC layer….Difference between PHY and MAC layer.
| Parameters | PHY Layer | MAC Layer |
|---|---|---|
| Position in OSI stack | Layer-1 | Layer-2 |
| Other name | Baseband or modem | Data link layer or Medium Access Control layer |
| Unit of data exchanged | Bits | Frames |
How fast is RGMII?
RGMII operates at 125 MHz in Gigabit mode, 25 Mhz in 100 Mbps mode and 2.5 MHz in 10Mbps mode.
What is PHY device?
What is the difference between RMII and PHY?
The RMII specification is also capable of supporting 10 Mbps and 100 Mbps data rates, and there are gigabit-capable variants. In RMII, the clock frequency used in the PHY runs continuously at 50 MHz for both 10 Mbps and 100 Mbps data rates.
What is the impedance of a RMII signal?
The RMII signals are treated as lumped signals rather than transmission lines. However, the IEEE version of the related MII standard specifies 68 Ω trace impedance. National recommends running 50 Ω traces with 33 Ω series termination resistors for either MII or RMII mode to reduce reflections.
What is the difference between RMII and Mii?
In MII, each PHY requires 18 signals to communicate with the MAC, and only 2 of these signals can be shared among multiple PHY devices. Therefore, RMII (reduced MII) was developed as a variant of MII to cut the number of unshareable signals per PHY interface in half (down to 8 per PHY).
What is the difference between RMII and REF_CLK?
RMII requires a 50 MHz clock where MII requires a 25 MHz clock and data is clocked out two bits at a time vs 4 bits at a time for MII or 1 bit at a time for SNI (10 Mbit/s only). Data is sampled on the rising edge only (i.e. it is not double-pumped ). The REF_CLK operates at 50 MHz in both 100 Mbit/s mode and 10 Mbit/s mode.