[Discuss-gnuradio] tx_empty in fpga

[Loconut]

(originally posted on nabble without subscribing- previously was subscribed
as address@hidden)

Trying to fix the problem of the transmitter repeating the last sample when
the fifo empties for doing gmsk on BasicTX/RX and/or LFRX/TX.

bus_interface.v line 116 has:
assign txdata = tx_empty ? 32'b0 : txd;

which says to me, load 32 bits of 0 when tx_empty, otherwise load the data..
so why doesn't this work? Did I miss something (probably!)

As an alternative, what about in tx_buffer around line 69:
       if((load_next != channels) & !tx_empty)
         begin
            load_next <= #1 load_next + 4'd1;
            case(load_next)
              4'd0 : tx_i_0 <= #1 fifodata;
              4'd1 : tx_q_0 <= #1 fifodata;
              4'd2 : tx_i_1 <= #1 fifodata;
              4'd3 : tx_q_1 <= #1 fifodata;
              4'd4 : tx_i_2 <= #1 fifodata;
              4'd5 : tx_q_2 <= #1 fifodata;
              4'd6 : tx_i_3 <= #1 fifodata;
              4'd7 : tx_q_3 <= #1 fifodata;
            endcase // case(load_next)
         end // if ((load_next != channels) & !tx_empty)

what if instead of checking for tx_empty and loading fifodata we do this:
       if(load_next != channels)
         begin
            load_next <= #1 load_next + 4'd1;
            case(load_next)
              4'd0 : tx_i_0 <= #1 tx_empty ? 16'd0 : fifodata;
              4'd1 : tx_q_0 <= #1 tx_empty ? 16'd0 : fifodata;
              4'd2 : tx_i_1 <= #1 tx_empty ? 16'd0 : fifodata;
              4'd3 : tx_q_1 <= #1 tx_empty ? 16'd0 : fifodata;
              4'd4 : tx_i_2 <= #1 tx_empty ? 16'd0 : fifodata;
              4'd5 : tx_q_2 <= #1 tx_empty ? 16'd0 : fifodata;
              4'd6 : tx_i_3 <= #1 tx_empty ? 16'd0 : fifodata;
              4'd7 : tx_q_3 <= #1 tx_empty ? 16'd0 : fifodata;
            endcase // case(load_next)
         end // if ((load_next != channels) & !tx_empty) 

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