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Programming the Ethernet controller (view source)
Revision as of 15:03, 19 July 2007
, 15:03, 19 July 2007no edit summary
=== (010) Idle ===
=== (010) Idle ===
inputs:
* ''Clk'': clock
* ''/Rst'': asynchronous, active-low reset
* ''State'': 3-bit state value
* ''TxRx_A'': 8-bit address from transceiver
* ''TxRx_D'': 8-bit data from transceiver
* ''TxRx_Done'': pulse from transceiver to signal transfer complete
internal signals
* ''S_En'': state enable, ''S_En'' <= not ''St(2)'' and ''St(1)'' and not ''St(0)''
* ''Go'': when ''S_En'' goes high ''Go'' pulses for one cycle
blocks
* '''Fetcher'''
** Reads register 0x76 (INT0RD) by sending a read request to the transceiver
** inputs
*** ''F_Go'': pulse to start request, ''F_Go'' <= ''Go'' or ''Loop''
** outputs
*** ''TxRx_Go'': ''Go'' line on transceiver
*** ''TxRx_R/W'': ''R/W'' line on transceiver, tied high (read)
*** ''TxRx_A'': ''A_in'' bus on transceiver, tied to 0x76 (0111 0110)
**** Note: ''D_in'' on transceiver is not used; assume this line defaults to zero
* '''Looper'''
** Switch to determine if this state should loop on itself or continue to the next state.
** inputs
*** ''S_En'': state enable
*** ''TxRx_Done'': ''Done'' pulse from transceiver
*** ''TxRx_Data'': ''D_out'' bus from transceiver
** outputs
*** ''Loop'': pulse to repeat fetch cycle; ''Loop'' <= ''S_En'' and ''TxRx_Done'' and ''TxRx_Data(6)''
*** ''Done'': pulse to finish state; connects to state counter as an enable in order to increment the state to 011; ''Done'' <= ''S_En'' and ''TxRx_Done'' and not ''TxRx_Data(6)''
=== (011) Read Packet ===
=== (011) Read Packet ===