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Programming the Ethernet controller (view source)
Revision as of 16:39, 14 November 2007
, 16:39, 14 November 2007→Reusable Components
Sends a write request (R/W pin low) to transceiver at the specified address with the specified byte of data. The primary reason of this instruction "packaging" was to obscure the complexity of appropriate delays to ensure proper signal latching. The delayed version is currently commented out under the assumption of falling edge of clock latching of data by the Transceiver.
Sends a write request (R/W pin low) to transceiver at the specified address with the specified byte of data. The primary reason of this instruction "packaging" was to obscure the complexity of appropriate delays to ensure proper signal latching. The delayed version is currently commented out under the assumption of falling edge of clock latching of data by the Transceiver.
=== 2-byte Write Request (<tt>wr2BtoAddr</tt>) ===
Coordinates write operations to two adjacent 1-byte registers in the Ethernet Controller chip. This is an essential abstraction because the controller often requires 16-bit exchanges especially when specifying 16-bit buffer locations in random memory access. Only the address of the first register needs to be passed in.
=== Byte Fetcher (<tt>getByte</tt>) ===
=== Byte Fetcher (<tt>getByte</tt>) ===
Fetches a byte of data from the Ethernet Controller registers via the Transceiver. This unit creates yet another abstraction layer "in series" with the transceiver. The two step process of sending a request with all accompanying parameters and waiting for reply is now a matter of a single "call". Aside from packaging, the component ensures proper timing among the sent signals. The actual request is performed via the <tt>reqFromAddr</tt> unit described below.
Fetches a byte of data from the Ethernet Controller registers via the Transceiver. This unit creates yet another abstraction layer "in series" with the transceiver. The two step process of sending a request with all accompanying parameters and waiting for reply is now a matter of a single "call". The actual request is performed via the <tt>reqFromAddr</tt> unit described above, so the timing characteristics are inherited from that module.
=== Auto-reader (<tt>AutoRd</tt>) ===
=== Auto-reader (<tt>AutoRd</tt>) ===
Performs the same function as the Byte Fetcher (described above) but is hard-wired to address the RXAUTORD (0x01). This is convenient because the Ethernet Controller's AutoRead interface will be used extensively to parse through packets. <tt>AutoRd</tt> is in fact a wrapper around <tt>GetByte</tt> passing through all signals accept the fixed address input.
Performs the same function as the Byte Fetcher (described above) but is hard-wired to address the RXAUTORD (0x01). This is convenient because the Ethernet Controller's AutoRead interface will be used extensively to parse through packets. <tt>AutoRd</tt> is in fact just a wrapper around <tt>GetByte</tt> passing through all signals accept the fixed address input.
=== Miscellaneous Components ===
=== Miscellaneous Components ===