并串转化指错，谢谢

module ptos(clk,ri,gi,bi,ro,go,bo);
output ro,go,bo;
input[7:0] ri,gi,bi;
input clk;
reg ro,go,bo;
reg[7:0] mem1,mem2,mem3;
reg[3:0] i,k;
always @(negedge clk)
begin
if(i==7)
begin
i<=0;
k<=1;
end
else
begin
i<=i+1;
i<=0;
end
end
always @(posedge k)
begin
mem1<=ri;
mem2<=gi;
mem3<=bi;
end

always @(posedge clk)
begin
ro<=mem1[7];
go<=mem2[7];
bo<=mem3[7];
  for(i=0;i<=6;i=i+1)
begin
mem1[i+1]<=mem1;
mem2[i+1]<=mem2;
mem3[i+1]<=mem3;
end
end
endmodule
错误是多驱动mem，但是我改不出来的，谢谢各位高手

不能在 多个ALEAYS中给同一个寄存器赋值