diff --git a/cpld/RAM.v b/cpld/RAM.v index 46b7e36..ca72224 100644 --- a/cpld/RAM.v +++ b/cpld/RAM.v @@ -7,7 +7,7 @@ module RAM( /* Select and ready signals */ input RAMCS, input RAMCS0X, input ROMCS, input ROMCS4X, /* RAM ready output */ - output RAMReady, + output reg RAMReady, /* Refresh Counter Interface */ input RefReqIn, input RefUrgIn, /* DRAM and NOR flash interface */ @@ -21,19 +21,18 @@ module RAM( reg RASrf; reg RefCAS; reg CASEndEN; - assign RAMReady = RASEN; /* Refresh command generation */ reg RefDone; // Refresh done "remember" always @(posedge CLK) begin - if (!RefReqIn) RefDone <= 0; + if (!RefReqIn && !RefUrgIn) RefDone <= 0; else if (RS[2]) RefDone <= 1; end wire RefReq = RefReqIn && !RefDone; wire RefUrg = RefUrgIn && !RefDone; /* RAM control signals */ - assign nRAS = !((!nAS && RAMCS0X && RASEN) || RASrf); + assign nRAS = !((!nAS && RAMCS && RASEN) || RASrf); assign nOE = 0;//!( !nAS && RAMCS && BACTr); assign nLWE = !(!nLDS && RASEL && !nWE); assign nUWE = !(!nUDS && RASEL && !nWE); @@ -65,7 +64,7 @@ module RAM( (RefUrg && !BACT) || // Urgent refresh during non-RAM access (RefUrg && BACT && !RAMCS0X); - wire RS0toRAM = BACT && RAMCS0X && RASEN; + wire RS0toRAM = BACT && RAMCS && RASEN; always @(posedge CLK) begin case (RS[2:0]) @@ -76,26 +75,31 @@ module RAM( RASEL <= BACT && RAMCS; RefCAS <= RS0toRef; RASEN <= !RS0toRef; + RAMReady <= !RS0toRef; end 1: begin // RAM access if (!nDTACK || !BACT) RS <= 2; // Cycle ending else RS <= 1; // Cycle not ending yet RASEL <= 1; RefCAS <= 0; RASEN <= nDTACK; + RAMReady <= 1; end 2: begin // finish RAM access RS <= 3; RASEL <= 0; RefCAS <= 0; RASEN <= 0; + RAMReady <= 1; end 3: begin //AS cycle complete if (RefUrg) begin // Refresh RAS RS <= 4; RefCAS <= 1; RASEN <= 0; + RAMReady <= 0; end else begin // Cycle ended so go back to idle/ready RS <= 0; RefCAS <= 0; RASEN <= 1; + RAMReady <= 1; end RASEL <= 0; end 4: begin // Refresh RAS I @@ -103,21 +107,25 @@ module RAM( RASEL <= 0; RefCAS <= 0; RASEN <= 0; + RAMReady <= 0; end 5: begin // Refresh RAS II RS <= 6; RASEL <= 0; RefCAS <= 0; RASEN <= 0; + RAMReady <= 0; end 6: begin // Refresh precharge I RS <= 7; RASEL <= 0; RefCAS <= 0; RASEN <= 0; + RAMReady <= 0; end 7: begin // Reenable RAM and go to idle/ready RS <= 0; RASEL <= 0; RefCAS <= 0; RASEN <= 1; + RAMReady <= 1; end endcase end