cortex M3 designstart 。

I  put two slaves on system AHB bus  , one is leds the other is switch .

I can write date to the leds' register  to control the led on or off,  but I can't read date from the switch data register .

i don't know what's wrong

here is the slave's code 

**************************************************************************************************

//Transfer Response
assign HREADYOUT = 1'b1; //Single cycle Write & Read. Zero Wait state operations

//read
always @(*)
begin
if( rHADDR==(`SWITCH_BASE ))
HRDATA <= {22'h0000_00,rSW};
end