Altera cyclone V Technical Reference page 2098

cv_5v4
18-8
MAC
2016.10.28
MAC
The MAC module implements the following functionality:
• USB transaction support
• Host protocol support
• Device protocol support
• OTG protocol support
USB Transactions
In device mode, the MAC decodes and checks the integrity of all token packets. For valid OUT or SETUP
tokens, the following DATA packet is also checked. If the data packet is valid, the MAC performs the
following steps:
1. Writes the data to the receive FIFO buffer
2. Sends the appropriate handshake when required to the USB host
If a receive FIFO buffer is not available, the MAC sends a NAK response to the host. The MAC also
supports ping protocol.
For IN tokens, if data is available in the transmit FIFO buffer, the MAC performs the following steps:
1. Reads the data from the FIFO buffer
2. Forms the data packet
3. Transmits the packet to the host
4. Receives the response from the host
5. Sends the updated status to the PFC
In host mode, the MAC receives a token request from the AIU. The MAC performs the following steps:
1. Builds the token packet
2. Sends the packet to the device
For OUT or SETUP transactions, the MAC also performs the following steps:
1. Reads the data from the transmit FIFO buffer
2. Assembles the data packet
3. Sends the packet to the device
4. Waits for a response
The response from the device causes the MAC to send a status update to the AIU.
For IN or PING transactions, the MAC waits for the data or handshake response from the device. For data
responses, the MAC performs the following steps:
1. Validates the data
2. Writes the data to the receive FIFO buffer
3. Sends a status update to the AIU
4. Sends a handshake to the device, if appropriate
USB 2.0 OTG Controller
Altera Corporation
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