Difference between revisions of "Programming the Ethernet controller"

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Line 35: Line 35:
  
 
inputs
 
inputs
 +
* ''Clk'': clock
 +
* ''/Rst'': asynchronous, active-low reset
 
* ''State'': 3-bit state value
 
* ''State'': 3-bit state value
 
* ''D_En'': DAC enable, assume held high/low by previous block
 
* ''D_En'': DAC enable, assume held high/low by previous block

Revision as of 14:36, 19 July 2007

Interface

See also: Ethernet packets
See also: Ethernet state diagram

Emulator

Controller

  • transceiver
    • This block provides a level of abstraction between the precise CP2200/1 interface and a generalized interface seen by the internal blocks of the FPGA. It takes information on the next transfer to carry out and returns information on the last transfer completed. It has a pulse signal to begin a transfer and a pulse signal to notify of a completed transfer. This eliminates a need for the internal workings of the FPGA to be aware of the timing of the interface; it simply begins a transfer and waits for notification of the transfer's completion.
    • inputs
      • CLK: clock
      • /Rst: asynchronous, active-low reset
      • Go: pulse to begin a transmission
      • R/W_in: read/write toggle: active-high read, active-low write
      • A_in: 8-bit bus for address to read to/write from
      • D_in: 8-bit bus for data to write; ignored during a read
    • outputs to internals
      • Done: pulse to signal completion of a transmission
      • R/W_out: read/write flag: active-high read, active-low write
      • A_out: 8-bit bus for address of last read/write
      • D_out: 8-bit bus for data of last read; internal systems should ignore for a write
    • outputs to CP2200/1
      • /CS: active-low chip select
      • MotEn: Motorola/Intel format toggle: active-high Motorola, active-low Intel
      • MuxEn: Multiplexed flag; not used for CP2201
      • ALE: ALE strobe
      • /Wr: Active-low write flag
      • /Rd: Active-low read flag
    • inouts
      • AD: 8-bit address and data bus

(000) Reset Cycle

inputs

  • Clk: clock
  • /Rst: asynchronous, active-low reset
  • State: 3-bit state value
  • D_En: DAC enable, assume held high/low by previous block
  • A_En: ADC enable, assume held high/low by previous block
  • E_En: Ethernet enable, assume held high/low by previous block

internal signals

  • S_En: state enable, S_En <= not (St(2) or St(1) or St(0))
  • Go: when S_En goes high Go pulses for one cycle
  • D_Go: DAC reset go pulse, D_Go <= Go and D_En
  • A_Go: ADC reset go pulse, A_Go <= Go and A_En
  • E_Go: Ethernet reset go pulse, E_Go <= Go and E_En

blocks

  • DAC Reset
    • Resets and initializes the DAC.
    • inputs
      • Clk: clock
      • /Rst: asynchronous, active-low reset
      • D_Go: go pulse to begin reset/initialization process
    • outputs
      • - All DAC reset/initialization control lines -
      • D_Done: goes high when reset/initialization process is complete, falls on D_Go pulse
  • ADC Reset
    • Resets and initializes the ADC.
    • inputs
      • Clk: clock
      • /Rst: asynchronous, active-low reset
      • A_Go: go pulse to begin reset/initialization process
    • outputs
      • - All ADC reset/initialization control lines -
      • A_Done: goes high when reset/initialization process is complete, falls on A_Go pulse
  • Ethernet Reset
    • Resets and initializes the Ethernet controller.
    • inputs
      • Clk: clock
      • /Rst: asynchronous, active-low reset
      • E_Go: go pulse to begin reset/initialization process
    • outputs
      • - All Ethernet reset/initialization control lines -
      • E_Done: goes high when reset/initialization process is complete, falls on E_Go pulse
  • Coordinator
    • Coordinates the completion of each reset cycle and notifies other blocks that the reset process is complete.
    • inputs
      • Clk: clock
      • /Rst: asynchronous, active-low reset
      • D_En: high when DAC is to be reset
      • D_Done: high when DAC is done resetting
      • A_En: high when ADC is to be reset
      • A_Done: high when ADC is done resetting
      • E_En: high when Ethernet controller is to be reset
      • E_Done: high when Ethernet controller is done resetting
    • internal signals
      • Flag <= (D_Done or not D_En) and (A_Done or not A_En) and (E_Done or not E_En)
    • outputs
      • Done: when Flag goes high, Done pulses for one cycle; connects to state counter as an enable (thereby incrementing the State to 001)