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Fixed rxfifotimeout restarting for every new character, even when already high.

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This commit is contained in:
Jacob Pease 2022-09-19 18:00:30 -05:00
parent 85b3e9bfe6
commit c797aee62c
1 changed files with 15 additions and 15 deletions
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30
pipelined/src/uncore/uartPC16550D.sv
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@ -82,7 +82,7 @@ module uartPC16550D(
logic DLAB; // Divisor Latch Access Bit (LCR bit 7)
// Baud and rx/tx timing
logic baudpulse, txbaudpulse, rxbaudpulse; // high one system clk cycle each baud/16 period
(* mark_debug = "true" *) logic baudpulse, txbaudpulse, rxbaudpulse; // high one system clk cycle each baud/16 period
logic [16+`UART_PRESCALE-1:0] baudcount;
logic [3:0] rxoversampledcnt, txoversampledcnt; // count oversampled-by-16
logic [3:0] rxbitsreceived, txbitssent;
@ -90,8 +90,8 @@ module uartPC16550D(
// shift registrs and FIFOs
logic [9:0] rxshiftreg;
logic [10:0] rxfifo[15:0];
logic [7:0] txfifo[15:0];
(* mark_debug = "true" *) logic [10:0] rxfifo[15:0];
(* mark_debug = "true" *) logic [7:0] txfifo[15:0];
logic [4:0] rxfifotailunwrapped;
(* mark_debug = "true" *) logic [3:0] rxfifohead, rxfifotail, txfifohead, txfifotail, rxfifotriggerlevel;
(* mark_debug = "true" *) logic [3:0] rxfifoentries, txfifoentries;
@ -99,7 +99,7 @@ module uartPC16550D(
// receive data
(* mark_debug = "true" *) logic [10:0] RXBR;
logic [6:0] rxtimeoutcnt;
(* mark_debug = "true" *) logic [6:0] rxtimeoutcnt;
logic rxcentered;
logic rxparity, rxparitybit, rxstopbit;
(* mark_debug = "true" *) logic rxparityerr, rxoverrunerr, rxframingerr, rxbreak, rxfifohaserr;
@ -107,16 +107,16 @@ module uartPC16550D(
(* mark_debug = "true" *) logic rxfifoempty, rxfifotriggered, rxfifotimeout;
logic rxfifodmaready;
logic [8:0] rxdata9;
logic [7:0] rxdata;
logic [15:0] RXerrbit, rxfullbit;
logic [31:0] rxfullbitunwrapped;
(* mark_debug = "true" *) logic [7:0] rxdata;
(* mark_debug = "true" *) logic [15:0] RXerrbit, rxfullbit;
(* mark_debug = "true" *) logic [31:0] rxfullbitunwrapped;
// transmit data
logic [7:0] TXHR, nexttxdata;
logic [11:0] txdata, txsr;
logic txnextbit, txhrfull, txsrfull;
(* mark_debug = "true" *) logic [11:0] txdata, txsr;
(* mark_debug = "true" *) logic txnextbit, txhrfull, txsrfull;
logic txparity;
logic txfifoempty, txfifofull, txfifodmaready;
(* mark_debug = "true" *) logic txfifoempty, txfifofull, txfifodmaready;
// control signals
(* mark_debug = "true" *) logic fifoenabled, fifodmamodesel, evenparitysel;
@ -154,7 +154,7 @@ module uartPC16550D(
//DLL <= #1 8'd38; // 35Mhz
//DLL <= #1 8'd11; // 10 Mhz
//DLL <= #1 8'd33; // 30 Mhz
DLL <= #1 8'd8; // 30 Mhz 230400
DLL <= #1 8'd11; // 30 Mhz 230400
DLM <= #1 8'b0;
end else begin
DLL <= #1 8'd1; // this cannot be zero with DLM also zer0.
@ -178,7 +178,7 @@ module uartPC16550D(
// freq /baud / 16 = div
//3'b000: if (DLAB) DLL <= #1 8'd38; //else TXHR <= #1 Din; // TX handled in TX register/FIFO section
//3'b000: if (DLAB) DLL <= #1 8'd11; //else TXHR <= #1 Din; // TX handled in
3'b000: if (DLAB) DLL <= #1 8'd8; //else TXHR <= #1 Din; // TX handled in
3'b000: if (DLAB) DLL <= #1 8'd11; //else TXHR <= #1 Din; // TX handled in
3'b001: if (DLAB) DLM <= #1 8'b0; else IER <= #1 Din[3:0];
3'b010: FCR <= #1 {Din[7:6], 2'b0, Din[3], 2'b0, Din[0]}; // Write only FIFO Control Register; 4:5 reserved and 2:1 self-clearing
3'b011: LCR <= #1 Din;
@ -275,7 +275,7 @@ module uartPC16550D(
rxstate <= #1 UART_ACTIVE;
rxoversampledcnt <= #1 0;
rxbitsreceived <= #1 0;
rxtimeoutcnt <= #1 0; // reset timeout when new character is arriving
if (~rxfifotimeout) rxtimeoutcnt <= #1 0; // reset timeout when new character is arriving. Jacob Pease: Only if the timeout was not already reached. p.16 PC16550D.pdf
end else if (rxbaudpulse & (rxstate == UART_ACTIVE)) begin
rxoversampledcnt <= #1 rxoversampledcnt + 1; // 16x oversampled counter
if (rxcentered) rxbitsreceived <= #1 rxbitsreceived + 1;
@ -357,8 +357,8 @@ module uartPC16550D(
(rxfifohead + 16 - rxfifotail);
// verilator lint_on WIDTH
assign rxfifotriggered = rxfifoentries >= rxfifotriggerlevel;
//assign rxfifotimeout = rxtimeoutcnt[6]; // time out after 4 character periods; *** probably not right yet
assign rxfifotimeout = 0; // disabled pending fix
assign rxfifotimeout = rxtimeoutcnt[6]; // time out after 4 character periods; *** probably not right yet
//assign rxfifotimeout = 0; // disabled pending fix
// detect any errors in rx fifo
// although rxfullbit looks like a combinational loop, in one bit rxfifotail == i and breaks the loop