FPGA Reset

(000) Reset Cycle

Block 000 will have four functional blocks: one each for the DAC, ADC, and Ethernet controller, and one to coordinate their completion. The temperature sensor lacks an external reset function; it self-initializes on startup. The "R" packet will supply flags as to whether or not to enable the various blocks. A power-on reset will default to resetting all components. Using the enable flags like a mask on the done lines, the fourth functional block will update the state register. For information on the reset procedures, see Reset and Initialization.

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 register as an enable
    • New_St: new state to be written to the state register; goes to 001 while Done is high